Free hours calculator — find the exact time duration between two times, add or subtract hours and minutes, and calculate work hours pay. Trusted by HR teams, freelancers, and project managers for fast, accurate time calculation.
Time difference & time addition/subtraction
This time calculator operates in two modes. Use "Hours Between Times" to calculate your exact work shift duration — enter your start and end times, subtract your break, and optionally enter your hourly rate to see pay earned. Use "Add / Subtract Time" to find the exact time after adding or subtracting hours, minutes, and seconds from any starting point. Both modes are useful for different everyday needs: shift workers calculating bi-weekly pay, freelancers tracking billable hours by client, project managers estimating sprint completion times, or anyone trying to figure out when a long flight will land in a different time zone.
For US workers, the Fair Labor Standards Act (FLSA) requires employers to pay 1.5x the regular hourly rate for all hours worked beyond 40 in a workweek — and some states like California have daily overtime rules (1.5x after 8 hours in a day, 2x after 12 hours). Accurately tracking your hours matters. A worker making $22/hour who works 45 hours in a week is owed $990 for the first 40 hours plus $165 for the 5 overtime hours — $1,155 total, not the flat $990 some employers mistakenly pay. Enter your exact hours in this work hours calculator to verify your paycheck before it hits your account.
Federal FLSA mandates 1.5x overtime for hours beyond 40/week. California also requires daily overtime — 1.5x after 8 hours, double-time after 12. Track your daily and weekly hours carefully and cross-check your employer's payroll calculations every period.
A 5-hour flight departing New York at 8:00 AM EST lands at 1:00 PM EST — but it's 10:00 AM in Los Angeles (PST). Use Add Time mode to calculate arrival in destination time. The US spans 6 time zones from Eastern (UTC-5) to Hawaii (UTC-10).
Freelancers and contractors should log time in 15-minute increments for accurate invoicing. If you charge $85/hour, a 3h 45m session earns $318.75. The work hours calculator handles the math — just enter start time, end time, and your rate.
Add working hours to estimate project completion. A 120-hour project starting Monday at 9 AM with 8-hour workdays finishes in 15 working days — approximately 3 calendar weeks, excluding weekends. Time math removes the guesswork from deadline setting.
Adding and subtracting durations is base-60 arithmetic, and the carry rules are what people get wrong: 60 seconds carry into a minute, 60 minutes into an hour, but 24 hours into a day. Mixing that with decimal intuition produces errors that look plausible. The dependable method is the same one used for timesheets — convert everything to a single unit, usually seconds, perform the arithmetic there, then convert back at the end with successive division and remainder. Durations crossing midnight need 24 hours added before subtracting, or the result comes out negative.
Total seconds = (h × 3,600) + (m × 60) + sBack to h:m:s — h = total ÷ 3,600, m = (total mod 3,600) ÷ 60, s = total mod 60Crossing midnight: add 86,400 seconds before subtractingwhere:
Assumptions: Duration arithmetic, not calendar arithmetic. Adding time across a daylight-saving transition requires timezone-aware date functions, since one local day that year is 23 or 25 hours long.
Sum 2:45:30, 1:38:45 and 0:52:20 by converting to seconds first.
Result5 hours 16 minutes 35 seconds
Adding the columns directly gives 3:135:95, which needs two carries to resolve — and it is exactly where mistakes creep in. In decimal hours the same total is 5.2764, which is correct for payroll but useless for reading as a clock time.