Time Duration Calculator

How to use

1. 1Type a duration into each row using clock notation like 1:23:45, unit notation like 2h 15m or 90s, or decimal notation like 2.5 with the row switched to Decimal hours.
2. 2Use the + or minus button at the start of each row to choose whether that duration is added to or subtracted from the running total.
3. 3Click Add duration to append more rows. Use the up and down arrows to reorder rows, and Remove to drop any row you no longer need.
4. 4Read the total on the right in HH:MM:SS, long form, days plus a clock remainder, and decimal totals in days, hours, minutes, seconds, and milliseconds.
5. 5Click Copy clock or any Copy button on a row to grab the exact format your spreadsheet, video editor, or project tool expects.

About this tool

Time Duration Calculator adds and subtracts a list of time durations entered in any of the formats people actually paste: clock notation like 1:23:45 or 0:30:15, unit form like 2h 15m, 45m, 90s, or 500ms, and decimal numbers like 2.5 hours or 90 minutes when you switch the row to a decimal mode. Each row carries a sign button, so you can subtract a 45 minute break from an 8 hour shift, take a 9:00 video down by an embedded 1:30 ad, or net out negative time on a project tracker. The running total updates instantly and is shown in seven formats at once: HH:MM:SS or DD:HH:MM:SS for clock-style readouts, a long-form sentence like 1d 2h 30m, days plus a clock remainder, and decimal totals in days, hours, minutes, seconds, and milliseconds. Each output has its own Copy button so you can paste exactly the format your spreadsheet, project tool, or video editor expects. A helper card breaks the running total into the sum of additions and the sum of subtractions so you can sanity check a long list at a glance. The parser is forgiving but explicit: a single colon is always treated as HH:MM, two colons as HH:MM:SS, three colons as DD:HH:MM:SS, and bare numbers prompt you to switch the row to decimal hours, decimal minutes, or decimal seconds so the result is never ambiguous. Useful for video runtimes and playlists, podcast episode lengths, exercise and pace splits, billable hour totals, study session logs, recipe and cooking timings, project tracking spreadsheets, and any place a calculator app's clock would round-trip you through clumsy mental math. Calculations run entirely in your browser, so the schedules and time logs you experiment with here never leave your device.

Free to use. Works in your browser. No signup, no login.