Time Calculator
Calculate time differences between two dates or times. Add and subtract hours, minutes, and seconds. Precise to the second.
Our free Time Calculator helps you find the exact duration between two dates or times, add or subtract hours, minutes, and seconds, and convert between time units. Use it for project deadline tracking (how many… Use the fields above to enter values and get an instant answer. All processing happens on your device.
About This Calculator
Our free Time Calculator helps you find the exact duration between two dates or times, add or subtract hours, minutes, and seconds, and convert between time units. Use it for project deadline tracking (how many days until launch?), timesheet calculations (total hours worked across shifts), event planning (duration between two dates), age-gap curiosity, or any task that requires precise time arithmetic. The calculator accounts for date boundaries and provides results in multiple formats — total days, total hours, and a broken-down years/months/days/hours/minutes/seconds view.
How It Works
Enter a start date/time and an end date/time. The calculator computes the absolute difference and breaks it down into years, months, days, hours, minutes, and seconds. It also provides the total as pure days, hours, or minutes for contexts where a single unit is more useful (e.g., timesheet hours). For the add/subtract mode, enter a starting time and a duration to add or subtract, and the calculator returns the resulting time. All calculations handle midnight crossings, month-length variations, and leap years correctly.
How to Use
- Enter your values in the calculator fields above
- Click the calculate button or let the calculator auto-update
- Review your results instantly
- Adjust values as needed to see different scenarios
Frequently Asked Questions
How do I calculate the number of days between two dates?
Enter the start date and end date. The calculator instantly shows the total number of days (and optionally years, months, and remaining days). For example, from January 1 to March 15 in a non-leap year is 73 days.
Can I add or subtract hours and minutes from a time?
Yes. Enter a starting time, then specify the hours, minutes, and/or seconds to add or subtract. The calculator returns the resulting time, handling midnight crossings automatically. This is useful for shift scheduling, cooking timers, and travel planning across time zones.
How do I calculate total hours worked for a timesheet?
Enter your clock-in time as the start and clock-out time as the end for each day. The calculator returns the duration in hours and minutes. Sum the durations across days for your weekly or bi-weekly total. For overnight shifts that cross midnight, the tool handles the date change automatically.
Does the calculator handle leap years?
Yes. Leap years (every 4 years, except centuries not divisible by 400) are fully accounted for. February has 29 days in leap years and 28 in common years, and the calculator adjusts all date differences accordingly.
Can I calculate how many weeks are between two dates?
Yes. The total-days result can be divided by 7 to get weeks. The calculator also shows the breakdown directly. For example, 45 days = 6 weeks and 3 days.
Why Use Our Free Time Calculator Online?
Our Time Calculator uses standard formulas and works in your browser—no install or sign-up. Use it for homework, travel, or everyday conversions. Results are instant and we don't collect your inputs. Explore our other math and unit converters from the link below.