Date calculator

What is the Date Calculator?

The Date Calculator is a free tool for two of the most common date-related questions: "How many days are between these two dates?" and "What date is a certain number of days from now?" Both calculations run instantly in your browser as you type or pick a date — there's nothing to submit and nothing is saved.

It's built for anyone planning around dates — project managers tracking deadlines, event planners counting down, or anyone who just needs to know how many days separate two points in time.

How to use the "days between two dates" calculator

1. Pick a start date and an end date using the date pickers.
2. The tool immediately shows the exact number of days between them.
3. It also shows the equivalent in weeks and approximate months, so you can think about the gap in whichever unit makes sense for your situation.

The order you pick the dates in doesn't matter — the result is always shown as a positive number of days, regardless of which date is earlier.

How to use the "add or subtract days" calculator

1. Enter a starting date.
2. Enter a number of days to add or subtract.
3. A positive number moves the date forward (useful for things like "30 days from today"), while a negative number moves it backward (useful for "90 days before this deadline").

The tool also tells you which day of the week the resulting date falls on, so you immediately know if your deadline lands on a weekend or weekday.

How the calculation works

The calculator counts full calendar days between the two dates, correctly accounting for different month lengths (28, 29, 30, or 31 days) and leap years. Because it works entirely from your device's clock and calendar data, there's no risk of it being out of date or relying on an external service — it will always match your local calendar.

A note on the "months" figure

The "months" figure shown in the days-between result is an approximation, since months don't all have the same number of days — it's calculated by dividing the total days by the average month length (30.44 days). For exact month-and-day breakdowns (like "2 months and 14 days" precisely), the Age Calculator uses a more precise calendar-aware method that accounts for each specific month's actual length.

Worked examples

Days between two dates

From January 1 to March 15 of the same (non-leap) year is 73 days — 31 days remaining in January, 28 in February, and 14 more days into March.

Adding days to a date

If today is June 1 and you add 45 days, the result lands on July 16, since June has 30 days (leaving 15 days into July, plus one more day to reach 45 total).

Subtracting days from a date

If a deadline is December 25 and a contract requires action 60 days before that, subtracting 60 days lands on October 26.

Common uses

• Working out project deadlines or delivery dates
• Calculating the length of a trip, lease, or contract
• Finding out how many days are left until an event
• Checking payment due dates (e.g. "net 30 days" invoices)
• Planning backward from a fixed date, like a wedding, exam, or filing deadline
• Estimating how long a project phase or subscription period will run

Frequently asked questions

Does the calculator account for leap years?

Yes — leap years are factored in automatically wherever February 29 falls within the date range you're calculating.

Can I calculate dates far in the past or future?

Yes, the calculator works correctly across a very wide range of years, both historical and far into the future.

What happens if I subtract more days than the date allows, going before year 1?

The calculator will still compute a valid result as long as it falls within a normal calendar range supported by your browser's date handling.