Date Calculator

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

How to use the Date Calculator

  1. Enter your values. Fill in the fields with your numbers.
  2. Calculate. Press Calculate to run the date calculator.
  3. 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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  • Save & compare scenarios
  • Export results

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

Healthy Weight by Height: How to Read and Use Your Range

By the Super Simple Digital Tools Team · Updated June 2026

Most people picture a single 'goal weight', but health authorities actually define a healthy weight as a span. The reason is simple: a person of a given height can carry slightly more or less weight, depending on frame and muscle, and still be perfectly healthy. The Healthy Weight Calculator captures this by giving you a low and a high figure that bracket the recognised healthy BMI zone of 18.5 to 24.9, turning an abstract index into something you can read off a scale.

The arithmetic behind it is the BMI formula run in reverse. BMI equals weight in kilograms divided by height in metres squared. To find the weights instead of the index, you fix BMI at the two boundary values and rearrange: lower weight equals 18.5 times height squared, upper weight equals 24.9 times height squared. A person 1.60 m tall has a height squared of 2.56, so their healthy band is roughly 47 kg to 64 kg. Add a few centimetres of height and the whole window shifts upward, which is exactly why a borrowed weight target from a taller friend rarely fits.

Once you have the range, the useful question is where you want to sit within it. Landing anywhere inside 18.5 to 24.9 is considered healthy, but many people aim for the middle of their band to leave room for the normal daily swings of one to two kilograms caused by water, food and timing. If your current weight is above the top of the range, the gap to the upper bound is a modest, achievable first goal rather than the daunting jump to the lowest figure. Small targets are easier to keep.

It is worth being clear about what the number cannot tell you. BMI was designed for population screening and treats all weight the same, so it cannot see whether your kilograms are muscle or fat. A rugby player and a sedentary person of identical height and weight get the same band, even though their health picture differs. That is why clinicians pair BMI with waist circumference, blood pressure and other checks. The calculator is a fast first filter, not a diagnosis.

To get the most reliable reading, measure your height accurately without shoes and weigh yourself at a consistent time, ideally in the morning. Re-check your range only if your height changes, which for adults is rare, and track your weight against the band over weeks rather than reacting to a single reading. Used this way, the healthy weight range becomes a steady reference point that supports gradual, sustainable change instead of crash targets.

  • Measure height in bare feet and weigh yourself at the same time of day for a like-for-like comparison against your range.
  • Aim for the middle of your band rather than the bottom edge, so normal daily fluctuations of one to two kilograms do not push you out of range.
  • If you are above the range, set the upper bound as your first milestone instead of the lowest figure, then reassess.
  • Pair the result with a waist measurement, since waist size adds information about fat distribution that BMI alone cannot capture.

Read the full guide →

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

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