Use our Time Calculator to add or subtract durations, find the difference between two moments, convert between units, and even sum multiple intervals in seconds, minutes, hours, or days. It’s fast, accurate, and built for planning schedules, tracking work, and simplifying everyday time math.
What the Time Calculator can do
The Time Calculator is a versatile tool that handles common time arithmetic with ease. Whether you’re calculating an end time from a start time and duration, figuring out how long a task took, converting hours to minutes, or adding up a list of time entries, this calculator delivers instant, reliable results.
- Add a duration to a starting date and time to get a precise end timestamp.
- Subtract a duration to find when something started or to set deadlines.
- Compute the exact difference between two dates and times, including overnight spans.
- Sum multiple durations from timesheets, workouts, or project logs.
- Convert between seconds, minutes, hours, and days with clear breakdowns.
How to use the Time Calculator
Add or subtract a duration
Select “Add duration” or “Subtract duration.” Enter your start date and time, then specify the duration (hours, minutes, seconds). The calculator outputs the resulting date and time along with a human-friendly summary.
Find the difference between two date/times
Choose “Find difference.” Enter the start and end. If you skip the dates, the calculator assumes the same day; if the end time is earlier than the start time, it assumes the next day. You’ll get a breakdown in days, hours, minutes, and seconds.
Sum multiple durations
Pick “Sum multiple durations” and paste or type a list like “1:30:00, 0:45:20, 2:15”. Formats such as “45m”, “3600s”, or “1h 20m 15s” are supported. The tool tallies everything and shows totals in hours:minutes:seconds, total minutes, and total seconds.
Convert between time units
Choose “Convert duration.” Enter a value and select the source and target units. Conversions follow standard definitions: 60 seconds per minute, 60 minutes per hour, and 24 hours per day. You’ll see both the converted value and an equivalent formatted duration.
Why use this Time Calculator?
- Accuracy: Handles carry-over between seconds, minutes, and hours correctly.
- Flexibility: Works with dates, times, and a variety of input formats.
- Clarity: Results include both precise numbers and readable summaries.
- Speed: Instant calculations without spreadsheets or manual math.
Practical examples
Scheduling and planning
Planning a meeting or an event? Enter the start time and add the expected duration to find the end time. Reverse the process to figure out when to begin in order to finish by a deadline.
Timesheets and productivity
Freelancers and teams can paste a list of task durations to quickly compute total billable hours. The calculator gives totals in multiple units so you can invoice or report with confidence.
Fitness and personal goals
Track workouts or practice sessions by summing intervals, or convert total time spent into hours and minutes to visualize progress.
Tips for best results
- Use 24-hour time to avoid ambiguity (e.g., 18:30 instead of 6:30 PM).
- For differences without dates, the tool assumes the end is the next day if it precedes the start time.
- When summing durations, separate entries with commas or new lines. Acceptable formats include h:m:s, h:m, and unit-suffixed values like “90m” or “3600s”.
From simple conversions to complex schedules, the Time Calculator helps you move faster and plan smarter with dependable, easy-to-read results.