Reminder & Alarm Scheduler – Task Urgency Calculator
This tool helps you schedule reminders with smart urgency scoring, repeat cycles, and browser‑based notifications. Enter task details to see live priority and timing previews. All data stays in your browser, and alarms run in the background (best‑effort). Includes formulas, copy‑able summaries, and an outdoor‑contrast mode for readability. Use it to organize tasks, meetings, or habits with visual urgency bars and completion tracking.
Reminder & Alarm System Planner
Plan tasks, schedule alarms, track completion, and copy/export your setup
Tip: Browser alarms/notifications work best when this tab stays open. For critical medication/dementia care, use a dedicated mobile app or OS-level alarms.
Planning & Scheduling
CTA: Build your next alarm in 30 seconds
Fill the form below, tap Add Reminder, then use Copy All Data to paste into notes, email, or a project plan.
Reminder List (Calendar-like Table)
| Title | Category | When | Repeat | Priority | Urgency | Status | Actions |
|---|
Tip: On mobile, swipe horizontally to view all columns.
Copied to clipboard.
📅 Reminder & Alarm System Tool
Complete User Guide with Mathematical Formulas & Calculation Methods
1. Overview & Key Features of the Reminder & Alarm System
The Reminder & Alarm System Tool is a comprehensive browser-based application designed to help you manage tasks, deadlines, and appointments with precision. It uses mathematical formulas to calculate urgency scores and automatically schedules browser notifications.
- Smart Urgency Calculation: Automatically prioritizes tasks based on deadline proximity and importance
- Flexible Scheduling: Supports one-time and recurring reminders (daily, weekly, monthly, custom intervals)
- Browser Notifications: Native desktop alerts with sound escalation options
- Persistent Storage: All data saved locally in your browser (no server required)
- Export & Share: Copy formatted text or print to PDF
Unlike simple reminder apps, this tool uses quantitative formulas to calculate urgency scores based on multiple factors: priority level, time remaining until deadline, and estimated task duration. This mathematical approach ensures you focus on the most critical tasks first.
2. Getting Started: Step-by-Step Setup Guide
Initial Setup (First-Time Users)
1Enable Browser Notifications
Click the "Enable Notifications" button at the top of the tool.
Without notification permissions, the tool will still work but alerts will only appear as in-page toasts (less reliable if browser tab is closed).
2Add Your First Reminder
- Enter a descriptive Task Title (e.g., "Submit quarterly report")
- Select a Category from dropdown or create custom category
- Set Priority level (1 = Low, 5 = Critical)
- Choose Date and Time for the reminder
- Enter Estimated Duration in minutes
- Configure optional fields (repeat, snooze, notes, etc.)
- Click "Add Reminder"
3Schedule Browser Alarms
Click "Schedule All Reminders" to activate browser-based timers for all pending items.
The tool automatically fills today's date and current time + 10 minutes. You can accept these defaults and adjust other fields as needed.
3. Understanding All Input Fields & Their Impact
| Field Name | Unit/Format | Valid Range | Purpose & Impact |
|---|---|---|---|
| Task Title | Text | 1-80 characters | Brief description of the reminder. Displayed in alerts and table. Required field. |
| Category | Selection | Preset or Custom | Organizes reminders by type (Work, Personal, Health, etc.). Use for filtering/grouping. |
| Priority | Integer (P) | 1 to 5 | Critical for urgency formula. Higher values = more urgent. 5 = Critical, 1 = Low. |
| Date & Time | YYYY-MM-DD HH:MM | Any future datetime | When the reminder is due. Used to calculate time remaining (Δt) in formulas. |
| Timezone | UTC offset | -12 to +14 | Currently informational. Calculations use browser's local time. |
| Repeat | Selection | None, Daily, Weekly, Monthly, etc. | Makes reminder recurring. Tool auto-calculates next occurrence after due date passes. |
| Custom Interval | Value + Unit | 1-999999 (minutes/hours/days/weeks) | For "Custom" repeat mode. Example: "Every 3 days" or "Every 2 weeks". |
| Snooze Duration | Minutes | 0 to 240 | How long to delay when you snooze an alert. Currently informational (manual snooze). |
| Nag Mode | Minutes or Off | Off, 5, 10, 15, 30 | Repeats alert every X minutes until status changed to "Completed". Persistent reminders! |
| Notes | Text (multiline) | Unlimited | Additional details shown in alerts and table. Use for context, links, instructions. |
| Participants | Text | Unlimited | Names/emails of others involved. Informational field for meetings/collaborative tasks. |
| Escalation Level | Selection | None, Visual, Sound | "Sound" = plays beep tone when alert fires. "Visual" = notification only. |
| Estimated Duration (D) | Minutes | 1 to 100,000 | Critical for urgency formula. How long the task takes. Required field (min: 1). |
| Lead Time | Minutes | 0 to 1,440 (24 hrs) | Pre-alert sent X minutes before due time. Example: 15 min lead = alert at T-15min and T=0. |
| Status | Selection | Pending, Completed, Missed | Track reminder state. "Completed" stops nag alerts. "Missed" for overdue items. |
- Task Title: Must be 1-80 characters. Error shown if empty or too long.
- Estimated Duration: Must be ≥ 1 minute. Error shown if missing or zero.
- Priority: Automatically clamped to 1-5 range in calculations.
- Lead Time: Automatically clamped to 0-1440 minutes (0-24 hours).
4. Mathematical Formulas for All Calculations
This tool uses transparent mathematical formulas to calculate urgency scores and other metrics. All formulas are shown below in both LaTeX notation and plain text.
Formula 1: Time Remaining Calculation
LaTeX Notation:
$$\Delta t_{\text{mins}} = \frac{t_{\text{due}} - t_{\text{now}}}{60000}$$Plain Text:
Variable Definitions:
- Δtmins = Time remaining until deadline, in minutes
- tdue = Due date/time in milliseconds (Unix timestamp)
- tnow = Current date/time in milliseconds (Unix timestamp)
- 60000 = Conversion constant (1 minute = 60,000 milliseconds)
Example Calculation:
Given:
- Due time: 2026-02-04 14:00 = 1770410400000 ms
- Current time: 2026-02-03 10:00 = 1770309600000 ms
Calculation:
Formula 2: Time Remaining in Hours
LaTeX Notation:
$$\Delta t_{\text{hours}} = \frac{\Delta t_{\text{mins}}}{60}$$Plain Text:
Variable Definitions:
- Δthours = Time remaining until deadline, in hours
- Δtmins = Time remaining in minutes (from Formula 1)
- 60 = Conversion constant (1 hour = 60 minutes)
Example Calculation:
Given: Δtmins = 1680 minutes (from previous example)
Calculation:
Formula 3: Urgency Score (Core Formula)
LaTeX Notation:
$$U = \left(\frac{P}{\max(1, \Delta t_{\text{hours}})}\right) \times \left(\frac{60}{\max(1, D)}\right)$$Scaled to 0-100 Range:
$$U_{\text{scaled}} = \min\left(100, U \times 100\right)$$Plain Text:
Variable Definitions:
- U = Raw urgency score (unbounded)
- Uscaled = Urgency score scaled to 0-100 range
- P = Priority level (1 to 5)
- Δthours = Time remaining in hours
- D = Estimated task duration in minutes
- max(1, x) = Prevents division by zero; returns max of 1 or x
- min(100, x) = Caps value at 100
Formula Logic:
- First Term (P / Δthours): Higher priority and less time remaining = higher urgency
- Second Term (60 / D): Shorter tasks get slightly higher urgency (easier to complete quickly)
- Scaling (× 100): Converts raw score to intuitive 0-100 scale
- Max/Min Functions: Prevent mathematical errors and cap extreme values
Example Calculation:
Given:
- Priority (P) = 4 (High)
- Time remaining (Δthours) = 2 hours
- Duration (D) = 30 minutes
Calculation:
Formula 4: Urgency Level Classification
Piecewise Function:
$$ \text{Level} = \begin{cases} 4 & \text{if } U_{\text{scaled}} \geq 80 \text{ (Critical)} \\ 3 & \text{if } 50 \leq U_{\text{scaled}} < 80 \text{ (High)} \\ 2 & \text{if } 25 \leq U_{\text{scaled}} < 50 \text{ (Medium)} \\ 1 & \text{if } 0 < U_{\text{scaled}} < 25 \text{ (Low)} \\ 0 & \text{if } U_{\text{scaled}} = 0 \text{ (None)} \end{cases} $$Variable Definitions:
- Level = Integer classification (0-4) for color coding charts
- Uscaled = Urgency score from Formula 3 (0-100 range)
Visual: Urgency Level Color Coding
Formula 5: Completion Rate Percentage
LaTeX Notation:
$$R_{\%} = \frac{N_{\text{completed}}}{\max(1, N_{\text{total}})} \times 100$$Plain Text:
Variable Definitions:
- R% = Completion rate as percentage
- Ncompleted = Count of reminders with status = "Completed"
- Ntotal = Total count of all reminders
- max(1, x) = Prevents division by zero when no reminders exist
Example:
15 reminders completed out of 20 total:
5. Urgency Score Calculation System Explained
How the Urgency Score Works
The urgency score is a quantitative measure (0-100) that helps you prioritize tasks. It considers three key factors:
Factor 1: Priority Level (P)
- 5 = Critical: Must complete immediately (regulatory deadline, emergency)
- 4 = High: Very important, tight deadline
- 3 = Medium: Important but some flexibility
- 2 = Low: Can be delayed if necessary
- 1 = Minimal: Nice to do, no urgency
Factor 2: Time Remaining (Δthours)
Calculated automatically from your due date/time setting.
If Δthours becomes negative (deadline passed), the formula uses max(1, Δt_hours) to prevent mathematical errors. Past deadlines get treated as "1 hour remaining" for urgency calculation purposes.
Factor 3: Estimated Duration (D)
You must estimate how long the task will take (1-100,000 minutes).
Short tasks with approaching deadlines can become extremely urgent. Example: A 5-minute task due in 30 minutes might score higher than a 2-hour task due in 3 hours, because the short task can be "knocked out" quickly.
Urgency Score Interpretation Table
| Score Range | Urgency Level | Recommended Action | Example Scenario |
|---|---|---|---|
| 80-100 | 🔴 Critical | Drop everything and complete NOW | Priority 5 task due in 1 hour, 15 min duration |
| 50-79 | 🟠 High | Complete today, schedule dedicated time | Priority 4 task due in 4 hours, 30 min duration |
| 25-49 | 🟡 Medium | Schedule this week, monitor deadline | Priority 3 task due in 2 days, 60 min duration |
| 1-24 | 🔵 Low | Nice to do, can defer if needed | Priority 2 task due in 1 week, 45 min duration |
| 0 | ⚪ None | No urgency, backlog item | Priority 1 task due in 1 month, any duration |
Real-World Urgency Examples
Example 1: Tax Filing Deadline (Critical Urgency)
Inputs:
- Priority: 5 (Critical - IRS deadline)
- Due: Tomorrow at 11:59 PM (24 hours from now)
- Duration: 120 minutes (2 hours to complete forms)
Calculation:
Even "critical" tasks show low urgency if there's ample time. This is mathematically correct but may seem counterintuitive. Consider using Lead Time alerts (e.g., 12-hour pre-alert) for important deadlines.
Example 2: Quick Email Response (High Urgency)
Inputs:
- Priority: 4 (High - client waiting)
- Due: In 30 minutes
- Duration: 5 minutes (quick reply)
Calculation:
6. Reminder Scheduling & Next Occurrence Logic
How Browser Timers Work
When you click "Schedule All Reminders", the tool sets JavaScript timers in your browser. These timers trigger notifications at the specified times.
Timer Types Set Per Reminder
1. Lead Timer (Pre-Alert):
Fires X minutes before due time (based on Lead Time field).
2. Due Timer (Main Alert):
Fires exactly at due time.
3. Nag Timer (Repeat Alerts):
If Nag Mode is enabled, repeats alert every X minutes until status = "Completed".
Recurring Reminder Logic (Next Occurrence Calculation)
For repeating reminders, the tool automatically calculates the next occurrence after the current due time passes.
| Repeat Mode | Next Occurrence Rule | Example |
|---|---|---|
| None | One-time reminder; next due = original due | Due once on Feb 5 at 10:00 |
| Daily | Add 24 hours to last due time | Feb 5 10:00 → Feb 6 10:00 → Feb 7 10:00 |
| Weekdays | Add 1 day, skip Sat/Sun | Fri Feb 7 → Mon Feb 10 (skips weekend) |
| Weekly | Add 7 days to last due time | Feb 5 10:00 → Feb 12 10:00 → Feb 19 10:00 |
| Monthly | Same date next month (handles month-end edge cases) | Feb 5 10:00 → Mar 5 10:00 → Apr 5 10:00 |
| Custom | Add custom interval (X minutes/hours/days/weeks) | Every 3 days: Feb 5 → Feb 8 → Feb 11 |
Custom Interval Calculation
Formula:
$$\text{Interval}_{\text{ms}} = V \times C_{\text{unit}}$$Where:
- V = Interval value (1-999999)
- Cunit = Conversion constant based on selected unit:
Example: Every 3 days
If a reminder's due time is already in the past when you load the tool, it will automatically calculate the next future occurrence based on the repeat rule. The tool will not spam you with alerts for missed past occurrences.
Example: A daily reminder originally due on Feb 1 will jump to the next occurrence in the future (e.g., today or tomorrow) when you reload the page.
7. Advanced Features & Controls
Dashboard Metrics (Live Statistics)
The dashboard at the top displays real-time statistics:
| Metric | Definition | Formula |
|---|---|---|
| Total | Count of all reminders | Ntotal |
| Pending | Reminders with status = "Pending" | Count where status = "Pending" |
| Completed | Reminders with status = "Completed" | Ncompleted |
| Missed | Reminders with status = "Missed" | Count where status = "Missed" |
Urgency Visualization Chart
The bar chart shows the next 7 upcoming reminders sorted by due time. Bar height and color indicate urgency level:
Where:
- h = Bar height as percentage (15-90%)
- Uscaled = Urgency score (0-100)
Example:
Control Buttons Reference
| Button | Function | When to Use |
|---|---|---|
| Enable Notifications | Request browser notification permission | First-time setup; if you denied permission earlier |
| Test Alarm | Fires test notification after 5 seconds | Verify notifications are working; test sound escalation |
| Schedule All Reminders | Activates browser timers for all pending reminders | After adding/editing reminders; after browser restart |
| Sort by Urgency | Reorders table rows by urgency score (high → low) | Focus on most critical tasks first |
| Copy All Data | Copies formatted text summary to clipboard | Share plan via email; backup to external file |
| Export PDF | Opens browser print dialog (save as PDF) | Create printable hard copy; archive snapshots |
| Reset All | Clears all reminders and local storage (with confirmation) | Start fresh; remove test data |
| Show/Hide Formulas | Toggles mathematical formula reference box | Learn how calculations work; verify formula logic |
Per-Reminder Action Buttons
Each reminder row has three action buttons:
- Ring: Manually trigger alert for this reminder (test or immediate notification)
- Edit: Populate form with this reminder's data for editing (deletes original, you re-add)
- Delete: Permanently remove this reminder (clears timers, no confirmation)
Outdoor Contrast Mode
Increases text contrast and border visibility for use in bright environments (sunlight, outdoors). Background remains white but text becomes darker and borders more defined.
How to Enable: Toggle the switch labeled "Outdoor Contrast" in the top controls. Your preference is saved automatically.
8. Accuracy Notes & Browser Limitations
This tool uses JavaScript timers (setTimeout/setInterval) which are best-effort only. Browsers may delay or skip timers under certain conditions.
When Timers May Fail or Delay
| Scenario | Impact on Alerts | Mitigation Strategy |
|---|---|---|
| Browser tab closed | All timers stop; no alerts fired | Keep tab open in background; pin tab; use desktop notification sounds |
| Computer sleep/hibernate | Timers paused; may resume late or not at all upon wake | Set multiple lead time alerts; use external calendar backup |
| Browser restart | All timers cleared (data persists but not scheduled) | Click "Schedule All Reminders" after restart |
| Low battery mode (mobile) | Browsers may throttle or kill background timers | Keep device plugged in for critical reminders |
| Background tab (Chrome) | Timers limited to 1 execution per minute in inactive tabs | Keep tool tab active/visible for critical periods |
| Network outage | No impact (tool works offline) but web notifications require online | Tool continues working; notifications may not display |
Reliability Recommendations
- Enable browser notifications and allow sound permissions
- Pin the tool tab in your browser to prevent accidental closure
- Keep browser running during important reminder periods
- Set lead time alerts (15-30 min before due) as backup warnings
- Use nag mode for critical tasks to get repeated reminders
- Backup critical deadlines in a calendar app (Google Calendar, Outlook) as redundancy
- Re-schedule after browser restart: Click "Schedule All Reminders" if you close and reopen your browser
Data Persistence vs. Timer Persistence
Your reminder data (titles, dates, notes) is permanently saved in browser localStorage and persists across sessions.
Timer schedules are NOT permanently saved and must be re-activated by clicking "Schedule All Reminders" each time you restart your browser or reload the page.
Accuracy of Calculations
All mathematical calculations (urgency scores, time remaining) are 100% accurate based on the formulas provided. Any discrepancies stem from:
- Clock skew: Your device's system clock must be accurate
- Timezone settings: Tool uses browser's local timezone (set via OS settings)
- Rounding: Urgency scores are rounded to 1 decimal place for display (internal calculations use full precision)
9. Common Mistakes & How to Avoid Them
❌ Mistake 1: Not Enabling Notifications
User adds reminders but never clicks "Enable Notifications" button. They miss all alerts because browser permission was denied.
Always click "Enable Notifications" during first-time setup and select "Allow" in browser prompt. Check the "Reliability" badge—it should say "Better (notifications on)" if working.
❌ Mistake 2: Forgetting to Schedule After Adding Reminders
User adds 10 reminders but never clicks "Schedule All Reminders". Timers are not activated so no alerts fire.
Click "Schedule All Reminders" after adding or editing reminders. You'll see a toast confirmation: "Browser timers set for all reminders".
❌ Mistake 3: Closing Browser Tab
User sets important reminder, then closes the browser tab. Timer stops and alert never fires.
Keep the tool tab open (can be in background). Pin the tab in your browser to prevent accidental closure. Use browser notifications so you get alerts even when tab is minimized.
❌ Mistake 4: Setting Unrealistic Durations
User estimates task duration as "5 minutes" for a complex project. Urgency score becomes artificially high, skewing prioritization.
Be realistic about estimated duration. Include time for review, breaks, unexpected issues. Example: Writing a 2-page report might take 60 minutes, not 15 minutes.
❌ Mistake 5: Confusing Date/Time Formats
User enters time in 12-hour format (2:00 PM) but browser expects 24-hour format (14:00). Reminder gets scheduled for wrong time.
Use the date/time picker controls (click calendar icon). Browser will enforce correct format. For manual entry, use 24-hour format: 14:00 not 2:00 PM.
❌ Mistake 6: Not Understanding Urgency Scores
User sees low urgency score (15) for a Priority 5 task and thinks the tool is broken. Actually, the task is due in 48 hours so urgency is correctly calculated as low.
Urgency ≠ Importance. The formula considers time remaining. A critical task due in 2 weeks has low urgency today (but will increase as deadline approaches). Use Lead Time alerts for important far-future items.
❌ Mistake 7: Ignoring Lead Time Alerts
User sets a reminder for 2:00 PM but forgets to set Lead Time. They get alert at 2:00 PM but task requires 30 min prep—too late!
Always set Lead Time for tasks requiring preparation. Example: Meeting at 2:00 PM → Set 15 min lead time → Get pre-alert at 1:45 PM to gather materials.
❌ Mistake 8: Not Using Status Field
User completes task but forgets to change status to "Completed". Nag mode keeps firing alerts every 10 minutes.
Update Status dropdown as soon as task is done. This stops nag alerts and improves dashboard statistics. Use "Missed" for overdue items you couldn't complete.
10. Troubleshooting & Frequently Asked Questions
Q: I'm not receiving any notifications. What's wrong?
Troubleshooting steps:
- Check browser notification permission: Click "Enable Notifications" and ensure you selected "Allow"
- Verify timers are scheduled: Click "Schedule All Reminders" button
- Test with "Test Alarm" button: Should see notification in 5 seconds
- Check browser settings: Go to browser Settings → Privacy/Notifications → Ensure notifications not blocked for this site
- Keep tab open: Timers won't fire if tab is closed
Q: My urgency scores seem wrong. How is this calculated?
Urgency scores are mathematically derived using Formula 3 (see Section 4). Common misunderstandings:
- "Priority 5 task shows low urgency" → Likely due in distant future. Urgency considers time remaining, not just priority.
- "Short task shows higher urgency than long task" → Correct! Formula boosts short tasks (60/D term) because they can be completed quickly.
- "Score changes over time" → Yes! As deadline approaches, Δt decreases and urgency increases automatically.
Click "Show Formulas" button to see live calculation breakdown.
Q: Can I sync reminders across devices?
No, data is stored locally in browser localStorage. Each device/browser has separate data. For cross-device sync:
- Use "Copy All Data" to export text, paste into cloud note (Google Keep, Notion)
- Use "Export PDF" to save snapshot to cloud storage
- Manually re-enter reminders on each device
Q: What happens if I close my browser?
Data persists, but timers do not.
- ✅ Your reminders are saved and will reload when you reopen the page
- ❌ Timer schedules are lost and must be re-activated
- Action required: Click "Schedule All Reminders" after reopening browser
Q: Can I delete all reminders at once?
Yes. Click "Reset All" button. You'll see a confirmation dialog ("Reset all reminders and clear local storage?"). Confirm to permanently delete all data.
This action cannot be undone. Export data first if you want a backup.
Q: How do I edit an existing reminder?
Current process (simple edit):
- Click "Edit" button on the reminder row
- Form populates with that reminder's data
- Original reminder is deleted automatically
- Make your changes in the form
- Click "Add Reminder" to save edited version
Note: Edit mode is destructive (deletes original). Make sure you want to proceed before clicking Edit.
Q: Why does "Weekdays" repeat skip weekends?
By design! "Weekdays" mode automatically advances to the next Monday-Friday date, skipping Saturdays and Sundays. This is useful for work-related reminders.
Example: Reminder due Friday Feb 7 → Next occurrence Monday Feb 10 (skips Sat Feb 8, Sun Feb 9)
Q: What is "Nag Mode" and when should I use it?
Nag Mode repeats the alert every X minutes until you mark the reminder as "Completed". Use for:
- Time-sensitive tasks you might forget (e.g., "Take medication")
- Reminders you need to act on immediately (e.g., "Join video call")
- Tasks you tend to procrastinate
Settings: Off, 5 min, 10 min, 15 min, 30 min
To stop nagging: Change Status dropdown to "Completed"
Q: How accurate are the timers?
JavaScript timers are typically accurate to within ±1 second under ideal conditions. However, accuracy degrades when:
- Tab is in background (throttled to 1/min in Chrome)
- CPU is under heavy load
- Computer enters sleep mode
- Battery saver mode is active (mobile)
For critical deadlines: Use redundant systems (external calendar, phone alarm, email reminder).
Q: Can I customize the urgency formula?
Not in the current version. The formula is hardcoded. However, you can influence the score by:
- Adjusting Priority (1-5)
- Setting realistic Estimated Duration
- Using Lead Time to get earlier warnings
For advanced users: The source code is in the document. You can modify the calcUrgencyScore function and self-host.
Q: What browsers are supported?
Tool is tested and works on:
- ✅ Chrome/Edge (Windows, Mac, Linux)
- ✅ Firefox (Windows, Mac, Linux)
- ✅ Safari (Mac, iOS)
- ⚠️ Mobile browsers (works but timers less reliable)
Minimum requirements: ES6 JavaScript support, localStorage, Notifications API (optional but recommended)
