Local · Private · Free

Date Calculator

Days between dates, add or subtract durations, and your exact age, calculated precisely in your browser. No data leaves your device.

From date

To date

Count business days only (Mon, Fri)

Start date

Operation

Years

Months

Weeks

Days

Date of birth

Age on dateDefaults to today, change it to find age on any date.

Calculated locally, nothing is sent anywhere.

Calendar math, done right

Months and years have different lengths and leap years shift February, so "3 months from now" isn't simply 90 days. This calculator uses true calendar arithmetic for adding, subtracting and measuring ages, and can count working days for project planning. It all runs in your browser: fast, private and free forever. Need help planning a project timeline? Digital Heroes can help.

About Date Calculator

Date Calculator is a free, private productivity tool that runs entirely in your web browser. It covers three modes: days between two dates, add or subtract a duration, and exact age with birthday countdown. It also counts business days (Monday to Friday) for project planning. Because everything happens locally on your device, your data is never uploaded to a server. There is no sign-up and no installation required. Like every free tool by Digital Heroes, it is 100% free with no limits.

What you can do

Count days between two dates, broken down into years, months, weeks, and hours.

Count business days between any two dates, with weekends automatically excluded.

Add or subtract years, months, weeks, and days from a start date using true calendar arithmetic.

Calculate exact age in years, months, and days from a date of birth.

See the next birthday countdown, including the age the person will turn.

Check the weekday of any resulting or target date instantly.

How to use Date Calculator

Open Date Calculator. It loads instantly in your browser with no sign-up.

Choose a tab: Difference to measure the gap between two dates, Add / Subtract to move a date forward or back, or Age for an exact age and birthday countdown.

Enter your dates. Results update instantly as you type. Toggle business days in the Difference tab to exclude weekends.

Read the result. Your data never leaves your device.

Frequently asked questions

Is Date Calculator free?

Yes, Date Calculator is completely free for everyone. No sign-up, no account and no usage limits.

Is it private? Are my files uploaded anywhere?

No. Date Calculator runs entirely in your browser on your own device, so your data never leaves your computer and nothing is uploaded to a server.

Does it work offline?

Yes. This tool is a Progressive Web App, once the page has loaded it keeps working offline, and you can install it as an app from your browser.

Do I need to install anything or create an account?

No. Just open the page and start using it. Installing it as an app is optional and only adds offline convenience.

What does Date Calculator do?

It measures the difference between two dates in days, weeks, months, and years. It lets you add or subtract years, months, weeks, and days from any start date. It calculates your exact age and shows a countdown to the next birthday. The business-day filter excludes weekends for project planning.