Time Calculator

Calculate time difference, duration between two times, add or subtract hours and minutes, and convert between time units — all with step-by-step solutions.

Calculate

Format: HH:MM or HH:MM:SS (24h)

Select a calculation type, enter your values, and click Calculate to see results with step-by-step solution.

Complete User Guide

About This Calculator

This time calculator handles four common time operations: finding the difference between two clock times, adding or subtracting a duration from a time, converting between time units (seconds, minutes, hours, days, weeks), and calculating the duration between a start and end time — with automatic midnight-crossing support.

4 Calculation Types

Time Difference

Find the exact difference between two clock times in hours, minutes, and seconds.

Add / Subtract

Add or subtract hours, minutes, seconds, or days from any clock time.

Convert Units

Convert between seconds, minutes, hours, days, and weeks.

Duration

Calculate how long from start to end. Handles overnight/midnight crossing.

Key Formulas

Difference: |Time₂ − Time₁| (in seconds)

Add: Time + Amount → mod 86400

Convert: Value × FromFactor ÷ ToFactor

Duration: End − Start (or 86400 − Start + End)

Important Notes

  • Use 24-hour format: 0:00 to 23:59. For example, 2:30 PM = 14:30.
  • Duration handles midnight crossing: Start 22:00, End 06:00 = 8 hours.
  • Add/subtract wraps around 24 hours. Subtracting past midnight adds 24h.
  • 1 day = 86,400 seconds, 1 week = 604,800 seconds.

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