SixtySum - Time Calculator

Time isn't decimal. Your calculator shouldn't be either.

SixtySum is a calculator built for one job: adding and subtracting hours, minutes, and seconds — fast.

A regular calculator works in tens. Time works in sixties. SixtySum does the base-60 math for you, so 50 minutes plus 20 minutes is 1 hour 10 minutes — not 70.

Tap H, M, or S, type the numbers, and go. No colon to fumble with. No menus to dig through. No internet to wait for.

WHO IT'S FOR
Video editors, streamers, audio and stage crews, and anyone who works by the clock and needs the total now — not after another web search.

WHAT YOU CAN DO
- Add and subtract HH:MM:SS values
- Switch instantly between H / M / S input
- Drop in 15m / 30m / 45m with a single tap
- Chain calculations without stopping
- See negative results for time differences
- Review your last 20 calculations at a glance

QUIET BY DESIGN
- One-time purchase — buy it once, keep it
- No ads
- No subscription
- No login or account
- No tracking
- Works fully offline

SixtySum stays out of your way and just gives you the number.

Note: Calculation history is kept for the current session only and is not saved permanently.