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Date Calculator

Add or subtract days, weeks, months and years from any date.

Add / Subtract from a Date

Start Date

Years

Months

Weeks

Days

Operation

About Date Calculator

Converting between different units and formats shouldn't require googling formulas or downloading apps. Date Calculator handles it instantly in your browser, letting you add or subtract days, weeks, months and years from any date with precision. Results update in real time as you type, and all processing happens locally on your device.

How to Use

Enter a value Type the number you want to convert into the input field.

Select units Choose the source and target units from the dropdown menus.

Get instant results The converted value appears immediately as you type — no button press needed.

Copy the result Click the Copy button or select the output value to copy it for use elsewhere.

🔒 Privacy note: All processing happens locally in your browser. Your data is never sent to any server.

Why Use Date Calculator?

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Real-Time Conversion Results update instantly as you type — no need to press a button. Quickly compare multiple values or find the exact conversion you need.

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High Precision Date Calculator uses accurate conversion factors from international standards. Results are precise enough for engineering, scientific, and professional use.

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Mobile Ready Fully responsive design works perfectly on phones and tablets. Great for quick conversions when you're shopping, cooking, or traveling.

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All Common Units Covers the most commonly needed unit conversions, including both metric (SI) and imperial systems, so you always find what you're looking for.

Frequently Asked Questions

Set the start date to today and enter 90 in the Days field with the Add operation. The result shows the date exactly 90 days from now.

JavaScript's Date object handles month arithmetic correctly. Adding 1 month to January 31 gives February 28 (or 29 in a leap year), since February doesn't have 31 days.