Time Duration Calculator

This calculator finds the duration between two times in hours, minutes and seconds, and it handles spans that cross midnight without losing a day. You can also add or subtract a duration from a start time to find the end time, which is the version most people need when working out when a shift finishes or when a slow-cooked dish comes out.

Times can be entered in either 12-hour form with am and pm or in 24-hour form. Results come back as total minutes and as an hours-and-minutes breakdown, with decimal hours alongside for timesheets and billable work. The arithmetic underneath converts both times to minutes, subtracts, then converts back. From 9:15 AM to 5:45 PM that is (17×60 + 45) − (9×60 + 15), or 1065 − 555, giving 510 minutes, which reads as 8h 30min or 8.50 in decimal hours.

Longer spans follow the same logic with different units. Days between two dates are plain calendar subtraction, while working days need the weekends removed along with the 8 UK bank holidays. To turn a weekly figure into an annual one, multiply by 52 weeks, which is how 40 hours a week produces a theoretical 2,080 hours a year on paper.

British working time carries its own set of numbers. A standard full-time week is 35-40 hours, and the Working Time Regulations cap the average at 48 hours a week over a 17-week reference period unless the worker has opted out in writing. Statutory holiday is 5.6 weeks of your normal working week, which comes to 28 days for someone working five days, and it is pro-rated for part-timers, so a 22.5-hour week earns 16.8 days. Take that holiday, the bank holidays and a little sickness off the theoretical total and a real full-time year lands nearer 1,700-1,800 hours. Overtime carries no statutory premium in the UK and is paid at whatever the contract says.

Deadlines are where a duration turns into a legal cliff edge. Online consumer purchases carry a 14 calendar day cooling-off period from delivery. An Employment Tribunal claim must be brought within 3 months less 1 day of the incident. Personal injury claims run for 3 years from the injury or from the point of knowledge, contract claims for 6 years, and claims on a deed for 12 years. HMRC can assess 4 years back as standard, 6 where the taxpayer was careless and 20 where the error was deliberate. An executor has the executor's year, 12 months from the grant, and a residential property gain must be reported and paid inside 60 days. A mortgage offer usually holds for 90-180 days before it is reassessed.

Everyday processes run to their own rough clocks. Buying a house takes 12-16 weeks from accepted offer to completion, and selling around 22 weeks from listing. An HMRC refund arrives in 2-12 weeks. Probate is nominally 8-16 weeks, although some cases have been stuck past 6 months. A passport renewal takes 3-10 weeks, or about 1 week on the priority service, and the wait for a driving test ran 14-20 weeks in 2025. Giving notice of marriage at a register office has required 28 days since 2015, and a no-fault divorce cannot complete inside 26 weeks under the April 2022 rules. Fewer than 50% of patients get a same-day GP appointment, and NHS England met its 18-week referral target 65% of the time in 2024.

Calendar arithmetic has one wrinkle worth knowing about. A Gregorian year averages 365.2425 days, because a leap year falls every 4 years except in century years not divisible by 400. That is why 2000 was a leap year, 1900 was not, 2100 will not be and 2400 will. A century therefore averages 36,524.25 days and a month 30.44 days. Counted in seconds, a day is 86,400, a week is 604,800 and an eight-hour working day is 28,800, while a year comes to roughly 31.5 million, which puts 30 years at about 946 million seconds and 100 years at about 3.15 billion.