Date Calculator

Add or subtract days from any date to find the resulting date and day of the week. Free, instant, no signup.

Start date

Operation

Days

How to use the Date Calculator

Enter your values. Fill in the fields with your numbers.
Calculate. Press Calculate to run the date calculator.
Use the result. Copy the result or try a related tool next.

Why use our Date Calculator

Instant results. Enter your figures and the date calculator returns an answer in seconds.

Free & private. Runs in your browser — no signup, and nothing is sent to a server.

Accurate. Uses standard formulas so you can rely on the numbers.

Free to use — premium coming soon

FREE

✓ Unlimited calculations
✓ Instant results
✓ No signup

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About the Date Calculator

The Date Calculator does two jobs that everyone needs at some point: it tells you exactly how much time sits between two calendar dates, and it tells you the date that lands a set number of days, weeks, months, or years before or after a starting date. Enter a start and end date to get the gap measured in years, months, weeks, and plain days, or pick a start date and add or subtract an interval to find a future or past date. It is built for the small but error-prone arithmetic of real life, from counting down to an event to nailing down a deadline.

Reach for it whenever a wrong count would cost you something. Use it to find a contract end date or notice period, the due date on an invoice, how many days are left until a flight or exam, a project milestone, a probation period, a medication schedule, or simply how old someone is in days. Because months have 28, 29, 30, or 31 days and years occasionally have 366, counting on your fingers or guessing from a wall calendar invites off-by-one mistakes. The calculator removes that guesswork and gives you a result you can put on a form, a quote, or a calendar with confidence.

Under the hood it converts each date to a day count on a continuous timeline, then subtracts the two to get the raw number of whole days. To break that span into years, months, and weeks it walks the calendar rather than dividing by a fixed average, so it respects the actual length of each month and adds February 29 in leap years (any year divisible by 4, except centuries not divisible by 400, so 2000 was a leap year and 1900 was not). Adding an interval works the same way in reverse, stepping forward or back across real month boundaries. You can usually choose whether the end date is counted, since 'days between' and 'days inclusive' differ by one.

Accuracy and privacy are both built in. The exclusive count (end date not counted) gives the number of full days between two dates; the inclusive count adds one and is the right choice for things like hotel nights or event spans where both the first and last day matter. Everything runs in your browser using your device's own calendar logic, so the dates you type, whether a birthday, a salary review, or a confidential deadline, are never uploaded to a server or stored. Close the tab and nothing is kept.

Frequently asked questions

How do I count the number of days between two dates?

Enter the earlier date as the start and the later date as the end. The standard 'days between' result subtracts the start from the end, so January 1 to January 10 is 9 days. If you want both the first and last day counted (the inclusive total), enable the include-end-date option to get 10.

What is the difference between inclusive and exclusive date counting?

Exclusive counting measures the full days between two dates and does not count the end date, so the same start and end date equals 0. Inclusive counting adds one to also count the final day, giving 1 for a single day. Use inclusive for hotel stays, event durations, and rental periods; use exclusive for the gap between two milestones.

Does the calculator account for leap years?

Yes. It uses real calendar lengths, so any span crossing February 29 in a leap year is counted correctly. A year is a leap year if it is divisible by 4, except century years, which must be divisible by 400 (2000 was a leap year, 1900 was not).

How do I find a date a certain number of days in the future or past?

Switch to add or subtract mode, enter your starting date, and type the number of days, weeks, months, or years to move. The tool steps across real month boundaries, so 'one month after January 31' returns the correct end-of-February date rather than a non-existent one.

Can it count only business days or working days?

When a weekday filter is available, you can exclude Saturdays and Sundays to count business days only. Note that this counts weekends out but does not know your local public holidays, so subtract those separately for legal or payroll deadlines that depend on them.

From our blog

From Step Count to Kilometres: How to Convert Your Daily Steps Accurately

By the Super Simple Digital Tools Team · Updated June 2026

Most fitness trackers were built around a single famous number: 10,000 steps a day. That target is useful for motivation, but it tells you nothing about distance. If your goal is to walk a certain number of kilometres, to compare a walk against a running route, or simply to understand what your daily total means, you first need to convert steps into distance. The conversion is straightforward arithmetic, but doing it well means understanding the one variable that drives the whole calculation: your step length.

The maths is simple. Distance in kilometres equals your step count multiplied by your step length in metres, divided by 1,000. So 8,000 steps at a 0.75 m step length works out to 8,000 x 0.75 / 1000 = 6 km. The reason published charts disagree is that they assume different step lengths. A widely cited average is about 1,312 steps per kilometre, but that figure quietly assumes an adult of roughly average height walking at a moderate pace. Shorter walkers take more steps per km, taller walkers take fewer.

Two details trip people up. The first is the step-versus-stride distinction: a step is one foot-fall, a stride is two. Because pedometers and phone apps count foot-falls, you must use step length, which is about half the stride length. Mixing them up roughly doubles your distance. The second is pace. Each step gets longer as you speed up, by something like ten percent between a slow stroll and a brisk walk, and even more when you jog, so a fixed step length will under-count the distance of a fast session.

The single biggest accuracy upgrade is to stop guessing your step length and measure it. Mark out a known distance, walk it naturally, count your steps, and divide. Do it a couple of times and average the results. Once you have your personal figure, every future conversion improves, and you can plug it into this calculator instead of relying on a generic default that may be off by five to ten percent for your build.

Used this way, a steps-to-km calculator becomes a planning tool rather than just a curiosity. You can work out that your habitual daily total is, say, 6.3 km, decide you want 7 km, and see how many extra steps that requires. You can sanity-check a new watch against your measured baseline, or estimate the step cost of a planned route before you leave. The conversion runs instantly in your browser, so you can experiment with different step lengths and counts as often as you like without anything leaving your device.

Measure your real step length once over a 10 m course, then reuse it every time for results that beat the generic averages.
Use step length, not stride length: stride spans two foot-falls and entering it will roughly double your distance.
Bump your step length up slightly for jogging or brisk walking, since each step lengthens as your pace rises.
To plan a target distance, divide it by your step length in km to estimate the steps needed, for example 5 km at 0.75 m is about 6,667 steps.

Read the full guide →

Tool by the Super Simple Digital Tools Team. Reviewed by our editorial team. Free to use, no signup required.