Time Calculator

Use it when your task matches one of these common needs: Add workout, study, video, podcast, or task durations. Subtract elapsed time from a planned duration. It works best when you already know the measurements, amounts, units, or options the page asks for.

In plain language: The calculator converts both durations to total seconds, adds or subtracts the second duration, then converts the result back to normalized hours, minutes, and seconds. Decimal hours are total seconds divided by 3,600. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.

First duration: the starting amount of time in hours, minutes, and seconds. Operation: choose add when combining durations or subtract when removing elapsed time from a planned amount. Second duration: the amount of time to add to or subtract from the first duration. Normalized result: the final answer with seconds and minutes rolled into the next larger unit when needed. Decimal hours: the same result as total seconds divided by 3,600, useful for rough logs or invoices.

Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.

This is duration math, not a time-zone, calendar, payroll, or clock scheduling calculator. Use the Hours Calculator for start and end times. Also check the unit, scale, mode, and result limit because small input changes can change the answer.

Use the Hours Calculator for start and end clock times. This Time Calculator works with durations such as 2 hours 45 minutes 30 seconds, not with wall-clock times such as 9:00 AM to 5:30 PM.

Keep minutes and seconds from 0 to 59. If you have 90 seconds, enter it as 1 minute 30 seconds. The result will still normalize rollovers, such as 59 minutes 50 seconds plus 25 seconds becoming 1 hour 0 minutes 15 seconds.

Decimal hours are the total seconds divided by 3,600. A result of 4 hours 6 minutes 15 seconds is about 4.1042 decimal hours.

A subtract calculation can go negative when the second duration is larger than the first. If that is not what you expected, swap the durations or use add mode.

Use it only for simple duration math. Payroll rounding, overtime, break rules, and employer policies need the Hours Calculator or your official timekeeping system.

No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.