What are the current cookie limits in modern browsers?

Question

What are the generic cookie limits for modern browsers, as of 2011? I'm particularly interested in:

• Max size of a single cookie
• Max number of cookies per host/domain name + path
• Max number of cookies per host/domain name
• Max number / max total size of all cookies in a given browser

I'm aware of RFC 2109 that specifies:

• at least 300 cookies
• at least 4096 bytes per cookie (as measured by the size of the characters that comprise the cookie non-terminal in the syntax description of the Set-Cookie header)
• at least 20 cookies per unique host or domain name

but what are real-world specs?

Answer 1

Here's a handy tool to test it: http://browsercookielimits.iain.guru/

It reveals quite a lot about the internal details regarding cookies. Click "Run Tests for Current Browser" for the results (it only takes a moment).

For example, I ran all tests for Google Chrome 10.0.648.134 beta:

22:23:46.639: Starting 22:23:47.345: Count: Max Cookie count with Character Length 3 and character "1": 180 22:23:50.131: Size: Max Cookie Character Length using character "1": 4096 22:23:52.347: Count: Max Cookie count with Character Length 4096 and character "1": 180 22:23:54.517: Size: Max Cookie Character Length using character "ÿ": 2049 22:23:57.450: Count: Max Cookie count with Character Length 2049 and character "ÿ": 180 22:23:59.41: Count: Max Cookie count with Character Length 100 and character "1": 180 22:24:0.535: Count: Max Cookie count with Character Length 10 and character "1": 180 22:24:2.88: Count: Max Cookie count with Character Length 5 and character "1": 180 22:24:2.886: Guessing Max Cookie Count Per Domain: 180 22:24:2.887: Guessing Max Cookie Size Per Cookie: 4096 bytes 22:24:2.887: Guessing Max Cookie Size Per Domain: NA 

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This answer is pretty old, but I just checked results for the latest Chrome version, and they're essentially the same. Edit: updated the answers for Chrome 54.0.2840.98 (64-bit).