Clock Calculator - Color Picker Studio

Clock Calculator

Free clock calculator: add/subtract/multiply time, clock angle solver, mirror clock, 12-24 hour conversion, world clock, sleep cycles, timesheet totals, stopwatch & timer.

🔒 100% Client-Side - All calculations happen in your browser. Nothing is uploaded.
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First Time

Second Time

Result

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Set Time

Angle Result

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🔄 Reverse: When is angle = X°?

🔄 12 ↔ 24 Hour

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⏳ What Time Will It Be? / Difference

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🌍 Time Zone Converter

Result

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😴 Sleep Cycle Calculator

Based on 90-minute sleep cycles + 15 minutes to fall asleep.

Best Times

📊 Enter Daily Hours (one per line)

Total

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🪞 Mirror Clock Solver

Formula: Real time = 11:60 − mirror time (12-hour format).

Real Time

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⏱️ Stopwatch

00:00.0

⏳ Countdown

05:00

Why Use Our Clock Calculator?

8 powerful time tools in one place - accurate, visual, and private.

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Visual Analog Clock

Live SVG clock that freezes on your results so you can see every answer.

📐

Angle + Reverse Solver

Calculate hand angles with step-by-step math, or find every time hands form your angle.

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Mirror Clock Solver

Instantly solve mirror-image clock puzzles using the 11:60 rule.

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World Clock + DST

Accurate time-zone conversion using the browser's IANA database, including DST.

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Sleep Cycle Planner

90-minute cycle suggestions for the best bedtimes and wake-up times.

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100% Client-Side

Everything runs in your browser. No uploads, no tracking, no waiting.

Frequently Asked Questions

How do I add or subtract two times? +

Open the Time Math mode, enter hours, minutes, and seconds for both times, then choose +, −, ×, or ÷. The calculator automatically handles base-60 carry-over (e.g., 2:45 + 1:30 = 4:15, not 3:75) and shows days if the total exceeds 24 hours.

How does the Clock Angle solver work? +

Enter any time in the Clock Angle mode. The tool shows the step-by-step calculation of the angle between the hour and minute hands, the reflex angle, and even lists every time in 12 hours when the hands form your chosen angle (Reverse solver).

How do I use the Mirror Clock solver? +

Enter the time you see in a mirror in the Mirror Clock mode. The tool applies the 11:60 rule to compute the real time instantly and displays it on the analog clock so you can verify visually.

How does the World Clock handle time zones and DST? +

The World Clock uses your browser's built-in IANA time-zone database, so Daylight Saving Time and half-hour zones (like India +5:30) are handled automatically. Pick a date, time, and two cities to convert between zones.

How does the Sleep Cycle calculator work? +

Choose whether you want to wake up at a time or go to sleep at a time. The tool counts in 90-minute cycles plus 15 minutes to fall asleep and suggests 4 options (3 to 6 cycles) so you wake between cycles, not mid-cycle.

How do I calculate my timesheet total? +

In the Timesheet mode, enter your daily hours one per line (e.g., 8:30). The tool adds them all and shows the total in H:MM:SS plus decimal hours, perfect for payroll and billing.

How do the Stopwatch and Countdown work? +

The Stopwatch lets you start, pause, reset, and record laps. The Countdown lets you set minutes and seconds, then counts down and shows a toast when finished. Both run entirely in your browser.

Is my data sent anywhere? +

No. All calculations happen 100% in your browser using JavaScript. Nothing is uploaded to any server - not your times, not your sleep schedule, not your stopwatch readings.