Time Calculator — Add, Subtract & Duration
Add or subtract days, hours, and minutes from a date-time, or find the exact duration between two times. 100% in your browser — free, no sign-up.
- ✓Free
- ✓No sign-up
- ✓Runs in your browser — files never uploaded
- ✓No watermark
How to
- 1Choose a mode: add/subtract time, or duration between two times.
- 2Enter the date-time(s) and the days/hours/minutes.
- 3Read the result instantly — calculated in your browser.
What does the time calculator do?
Two things: add or subtract a duration (days, hours, minutes) to a starting date and time, or measure the exact duration between two date-times. It handles the awkward parts — rolling over hours into days, crossing midnight, and month boundaries — so you do not have to count on your fingers.
Add or subtract time
Pick a start date and time, choose add or subtract, and enter days, hours, and/or minutes. The result updates instantly with the new date and time — handy for deadlines ("48 hours from now"), cooking, shifts, or scheduling.
Duration between two times
Enter a start and an end date-time and get the gap broken down into days, hours, minutes, and seconds, plus the totals (total hours, total minutes). Useful for timesheets, event lengths, project spans, or how long is left until a deadline.
When to use it
Work out a project deadline, log hours on a timesheet, plan a cooking or fasting window, find how many hours a shift covers, or count down to an event. It is the quick answer for any "what time will it be" or "how long between" question.
FAQ
What can it calculate?+
Two things: add or subtract days/hours/minutes from a date-time, and the exact duration between two date-times (days, hours, minutes, seconds + totals).
Does it handle crossing midnight and months?+
Yes. It uses real calendar dates, so adding hours rolls correctly across midnight, month ends, and leap days.
Is it different from the timestamp converter?+
Yes. This does human time arithmetic (add/subtract, duration). The timestamp converter turns Unix timestamps into dates and back.
Is my data sent anywhere?+
No. Everything is calculated in your browser.
Is it free?+
Yes, completely free — no sign-up and no watermark.
Is my data private?+
Yes — this tool runs entirely in your browser. Your files and text are never uploaded.
Related tools
- Age Calculator — Free, Exact Age
- Percentage Calculator — Free Online
- BMI Calculator — Free, Metric & Imperial
- Loan & Mortgage Calculator — Free
- Mortgage Calculator — Monthly Payment (PITI)
- Tip Calculator — Split the Bill Free
- Discount Calculator — Percent Off & Final Price
- Sales Tax Calculator — Add Tax to a Price
- ROI Calculator — Return on Investment
- Salary Calculator — Hourly to Annual Pay
- Date Calculator — Days Between Dates & Add Days
- Rent vs Buy Calculator — Which Is Cheaper?