Add Time Calculator — Add & Subtract Hours and Minutes

Total up a list of durations: project phases, practice sessions, travel legs, editing passes. Each row is hours and minutes, added or subtracted, and the running total appears in every form at once.

Why adding times goes wrong on paper

Durations are not decimal numbers. Adding 2:30 and 1:45 by treating them as 2.30 and 1.45 gives 3.75 — which looks like 3 hours 75 minutes, a time that does not exist. The correct route is the one this calculator takes: convert every entry to minutes (150 and 105), add or subtract in minutes (255, then −30 = 225), and convert back at the end (225 = 3 hours 45 minutes). Minutes past 59 are welcome in any row — 1 hour 90 minutes is simply read as 150 minutes — because that is how people jot times down in real lists.

What people total here

Freelancers summing task times for an invoice before they go into the time card; students adding up study blocks across a week; musicians totalling a setlist; travellers adding flight and layover legs to see the true door-to-door time; anyone reconciling a logbook against a required total — flight hours, training hours, volunteer hours — where the subtraction rows are the corrections.

Frequently asked questions

Can the total go negative?: Yes, and it is shown signed — "minus 1 hour 15 minutes (−1:15)" — which is what you want when the subtractions outweigh the additions, for example when reconciling estimated against actual time.
How many durations can I add?: As many rows as you need; the "+ Add another duration" button appends one at a time. There is no upload and no account — the list lives in the page until you close it.
What is the difference between this and the time card?: This tool adds lengths of time you already know. The time card calculator works from clock times — in at 9:00, out at 5:30 — and derives each day's length first.
Why show decimal hours for a simple sum?: Because the total usually ends up multiplied by something — an hourly rate, a price per hour of studio time. Decimal hours (3.75) multiply directly; 3:45 does not.