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Date Difference Calculator (Days Between Dates)

Calculate the exact number of days, weeks, months and years between any two dates — for countdowns, deadlines and milestones.

100% free No sign-up Private · runs in your browser

How to use the free online date difference calculator

Pick a start date and an end date.
Choose to include the end date or not.
Optionally count only business days.
See the total in days, weeks, months and years.

About this tool

Find the exact number of days, weeks, months and years between any two dates. Count business days only, include or exclude the end date, and see a breakdown for planning deadlines, projects, pregnancies and countdowns. Accurate for leap years and timezone-free — the answer is just a click away.

Key features

Days, weeks, months & years
Business days option
Any date range
Instant result

Privacy first: every calculation and generation runs 100% locally in your web browser using the Web Crypto API. Your input never touches a server — nothing is stored, logged or sold.

Read the guide

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Time zones, UTC and DST — the 5-minute explainer

How time zones actually work, why UTC exists, and how to convert times across the world without mistakes.

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The calendar math behind 'days between' — leap years, inclusive counting and the off-by-one trap.

Frequently asked questions

The calculator counts all calendar days between the start and end date. Toggle 'Business days' to count only Mon–Fri working days.

By default it measures the full span (e.g. Jan 1 to Jan 2 is 1 day). You can include or exclude the end date to match your convention.

Project deadlines, pregnancy due dates, loan terms, subscriptions, anniversaries, school semesters and holiday planning.