Why does a normal calculator get it wrong?

Typing 7 hours 45 as 7.45 makes it a decimal. 45 minutes is 0.75 of an hour, so the answer drifts. Here the 7:45 form is read as it is.

What formats can I write?

1:25, 85m and 1.5h all work. The totals box takes the same formats.

What if it passes midnight?

It shows that the result rolled into the next day — useful for night shifts and anything else that crosses a date.

Time add · subtract

Name: 시간 더하기·빼기
Author: KarmoLab

Add/subtract clock time · total hours worked · decimal hours

시간 더하기·빼기

시각에 시간을 더하거나 근무시간을 합산합니다. 60진법 실수를 막습니다

시각 더하기·빼기

시작 시각

걸리는 시간 — 1:25 / 85m / 1.5h

11:05

걸리는 시간1시간 25분

결과11:05

분으로85분

소수 시간1.42시간

시간 합계 — 한 줄에 하나 (7:45, 8h, 90m)

합계

22시간 55분

소수 시간

22.92시간

평균

7시간 38분

시각은 24시간을 넘으면 다음 날로 넘어갑니다.

Adds and subtracts time from a clock time, and sums several durations. Base 60 is easy to get wrong by hand or on an ordinary calculator; this gets it right.

How to use it

Enter the start time and the duration
Choose add or subtract
For totals, put one duration per line below

Common questions

Why does a normal calculator get it wrong?: Typing 7 hours 45 as 7.45 makes it a decimal. 45 minutes is 0.75 of an hour, so the answer drifts. Here the 7:45 form is read as it is.
What formats can I write?: 1:25, 85m and 1.5h all work. The totals box takes the same formats.
What if it passes midnight?: It shows that the result rolled into the next day — useful for night shifts and anything else that crosses a date.

Other tools

Stays on your device What you enter is handled inside your browser only — nothing is stored or sent anywhere.

This tool page states where what you enter goes — see the badge above. All tools · KarmoLab · Who made this · Built with AI. View source