HTTP headers
HTTP Retry-After calculator
Calculate a Retry-After wait from an explicit UTC reference time.
Your inputs
Start with an exampleYour result
Example resultAa — A small example of your colors.
How it works
Accept delay-seconds or an IMF-fixdate. Subtract the supplied reference time for dates; clamp past dates to zero wait.
120 at 2026-01-01T00:00:00Z gives a wait of 120 seconds and a target of 00:02:00Z.
Limits
No requests or scheduling. Date input uses the modern IMF-fixdate format and checks the weekday; obsolete HTTP date formats and leap seconds are excluded.