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Cookie Expiry Calculator

Calculate cookie expiration from a session length or an exact date. Get the Expires header, Max-Age seconds and a ready Set-Cookie directive. All processing runs locally in your browser. Your data is not uploaded to any server. 100% Local Processing

How to Use

Turn a session lifetime or an expiry date into the exact Expires and Max-Age values for a Set-Cookie header, calculated against the current moment.

Steps

1. Enter a session length in days, hours or minutes.
2. Or set an exact expiry date instead.
3. Click Calculate and copy the Max-Age and Expires values for your Set-Cookie header.

What the result shows

• The Expires date in the HTTP header format.
• The Expires date in your local timezone.
• Max-Age in seconds, the value modern browsers prefer.
• A complete Set-Cookie directive line ready to paste.

Features

• Sampling the current moment makes the header always fresh.
• Exact expiry dates override length-based calculations.
• Computed entirely in the browser.
• All processing runs locally in your browser. Your data is not uploaded to any server.

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