Time Calculator
Add or subtract multiple time values in hours, minutes, and seconds.
The Formula
Convert: 1 day = 24 hrs = 1,440 min = 86,400 sec
Time zones: add/subtract UTC offset
= 4 hours 45 minutes
= 4 × 60 + 45 = 285 minutes
Why Time Arithmetic Is Tricky
Time uses a base-60 (sexagesimal) number system for minutes and seconds, not the base-10 decimal system we use for everything else. That means you cannot just add time values the way you add regular numbers. Adding 1 hour 45 minutes and 1 hour 30 minutes does not equal 2 hours 75 minutes — it equals 3 hours 15 minutes (75 minutes carries over as 1 hour 15 minutes). Our calculator handles all the carrying and borrowing automatically, so you can add any number of time values and get the correct result instantly.
Common Uses for the Time Calculator
Tracking work hours: add up your daily time entries to find total hours worked in a week. Billing and invoicing: sum hours across multiple client projects or tasks. Fitness: total your exercise sessions for the week. Cooking and recipes: figure out when to start different dishes so they all finish at the same time. Travel planning: add up flight times, layover durations, and transfer times to find total travel time. Video production: sum clip durations for total project length.
Converting Between Time Formats
For payroll and billing purposes, time in hours and minutes is often converted to decimal hours. The formula is simple: divide the minutes by 60 and add to the hours. One hour and 45 minutes equals 1 + (45/60) = 1.75 hours. Two hours and 30 minutes equals 2.5 hours. This decimal format makes multiplication easy — 2.5 hours at $45/hour is straightforwardly $112.50.
Frequently Asked Questions
How do I add hours and minutes?
Add the minutes first. If the result is 60 or more, carry over: subtract 60 from minutes and add 1 to hours. Then add the hours. Our calculator does this automatically.