Date & Time Calculator
Calculate the difference between two dates, add or subtract durations, count business days, run a countdown, or work out working hours — instantly and 100% in your browser.
What this calculator does
The Date & Time Calculator answers everyday date questions without any math on your part. Pick a mode, enter two dates or a duration, and the answer appears immediately — days, hours, minutes and seconds, all clearly laid out and ready to copy.
- Difference — the exact time between two dates and times.
- Add / Subtract — what date is 45 days from today, or 6 months ago.
- Business Days — working days between two dates, skipping weekends and holidays.
- Countdown — a live countdown to a deadline, birthday or launch.
- Working Hours — net working time from a start and end time, minus breaks.
How to use it
Choose a mode from the selector at the top. Every mode starts with today's date already filled in, so most calculations take a single tap. Enter your values and the result updates live — there is no Calculate button to hunt for. When you have the answer, use Copy result to paste it into an email, message, or notes.
If you enter an end date that falls before the start date, the tool tells you clearly and offers to swap the dates or show the absolute difference, so you never get a confusing negative number.
Examples
- Monday 9:00 AM → Friday 5:00 PM = 4 days 8 hours (104 total hours).
- Today + 45 days gives the exact calendar date 45 days from now.
- 16 calendar days between two dates might be 12 business days once weekends are removed.
- 9:00 AM – 5:00 PM with a 1-hour break = 7 working hours.
Common uses
- Project deadlines, contract and notice periods, and SLA due dates.
- Subscription renewals, free-trial end dates, and warranty expiry.
- How many days until a trip, exam, wedding, or product launch.
- Freelance billing, timesheets, and overtime from working hours.
- Delivery and payment estimates counted in business days.
Frequently asked questions
How do I calculate the number of days between two dates?
Open the Difference mode, enter a start date and an end date, and the calculator instantly shows the number of days between them, along with the total hours, minutes, and seconds.
Can I add or subtract days from a date?
Yes. In Add/Subtract mode, enter a base date, choose Add or Subtract, and enter any combination of years, months, weeks, days, hours, and minutes. You can also use quick presets like +30 days or +1 year.
Does it count business days and skip weekends?
Yes. Business Days mode counts working days between two dates, excluding weekends. You can choose Saturday–Sunday, Friday–Saturday, or other weekend rules, and add specific holidays to exclude.
Is my data sent to a server?
No. Every calculation runs entirely in your browser using JavaScript. Your dates and times are never uploaded, stored, or shared.
What happens if the end date is before the start date?
The calculator warns you that the end date is before the start date and offers to swap the dates or calculate the absolute difference instead of showing a confusing negative result.
Can I calculate working hours with a lunch break?
Yes. Working Hours mode takes a start time, end time, and break duration, then shows the net working time — for example 9:00 AM to 5:00 PM with a 1-hour break is 7 working hours.