HTTP Date Converter

Convert any date to HTTP Date format (RFC 9110). Always in GMT.

Date or timestamp

What is HTTP Date?

HTTP/1.1 (RFC 9110) defines the "IMF-fixdate" format for date/time headers: Day, DD Mon YYYY HH:MM:SS GMT. Example: Mon, 15 Jul 2024 12:00:00 GMT. It's always expressed in GMT — never with a numeric offset. RFC 9110 obsoleted RFC 7231 in 2022; the format itself is unchanged.

HTTP Headers Using This Format

Date

When the response was generated

Last-Modified

When the resource was last changed

Expires

When the response becomes stale

If-Modified-Since

Conditional GET request header

If-Unmodified-Since

Conditional PUT/DELETE header

Retry-After

When to retry after 429/503 (can also be seconds)

Why Always GMT?

HTTP requires GMT to avoid ambiguity in caching and conditional requests. Intermediary proxies compare timestamps for freshness calculations — a consistent timezone eliminates conversion errors. Note: "GMT" in HTTP is semantically identical to UTC.