Calculator Tools
Calculate elapsed hours and minutes between clock times, add or subtract a duration with day rollover, or combine two durations. Exact minute arithmetic stays separate from time zones and daylight-saving rules.
Duration hours are limited to 100,000 per input. Minutes must be from 0 to 59.
Simple workflow
How to use Time Calculator
- 1Choose Time duration, Add or subtract time, or Add durations.
- 2Enter the labelled clock times or whole-hour and minute durations.
- 3Select Calculate time to see total minutes, normalized duration or the result clock and day offset.
Good to know
Frequently asked questions
How is an overnight duration handled?
If the end is earlier than the start, select End occurs next day. The tool requires that explicit choice instead of silently assuming an overnight interval.
Does this calculator use daylight-saving rules?
No. It performs clock-minute and duration arithmetic without calendar zones. Use Time Zone Converter when DST or named places matter.
Can I add or subtract across midnight?
Yes. The result wraps to a normalized clock time and says whether it is the same day, next day, previous day or farther away.
Does this version support seconds?
No. Wave 3A intentionally calculates whole hours and minutes. Each minutes input must be from 0 through 59.
Practical guide
Calculate clock differences and durations with exact minute arithmetic
Time duration mode subtracts a start clock time from an end time. When the end is earlier, select End occurs next day explicitly. Add or subtract mode wraps across midnight and labels the resulting day offset.
Add durations combines hours and minutes without a calendar date. All three modes use whole minutes, so their arithmetic is independent of locale, time zones and daylight-saving changes.
Worked example
Find a workday duration
- Start with
- Start 09:30 and end 17:15.
- Choose
- Choose Time duration and leave End occurs next day off.
- You get
- The duration is 7 hours 45 minutes, or 465 total minutes.
Tips for a useful result
- Select next day only when the end belongs to the following calendar day.
- Use Add or subtract time to see previous-day or next-day rollover.
- Use Time Zone Converter when two places or DST rules matter.
Scope, limits and privacy
This version calculates hours and minutes. Duration minutes must be from 0 through 59, and each duration-hour input is capped at 100,000. It does not calculate seconds, calendar dates or timezone offsets.
Times, durations and results remain in page memory. They are not sent to an API, analytics, browser storage or query string.
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