Propane Tank Recertification Date Calculator
A DOT propane cylinder is only good to refill for a set number of years from the date stamped on its collar — and refill stations are required to refuse an expired one. That stamp is easy to misread: a bare date, or a date next to a letter like "E" or "S" that changes the interval entirely. Pick what your stamp actually shows and its date, and get the real next-due date. Everything runs in your browser — nothing is uploaded.
Your tank's stamp
Result
This tool reads the RULE, not your tank — the interval and due-month shown are typical, sourced from 49 CFR 180.209 and current industry guidance (full citations below). The stamp physically on your cylinder, and the requalifier who last serviced it, always override this page. Never fill or use a cylinder past its stamped due date; a refill station is required by law to refuse it. Being within date doesn't mean the tank is undamaged — this tool can never tell you a cylinder is safe: never fill or use one that's dented, rusted or corroded, or has a damaged valve, regardless of what date it shows.
What do the stamp letters mean?
A DOT propane cylinder's collar carries a date stamp. A bare date with no letter is the original manufacture date — the cylinder is good for 12 years from then before its first requalification is due. When a cylinder is requalified, the new stamp adds a letter: "E" means it passed an external visual inspection, good for another 5 years — the method almost every consumer exchange or refill counter actually performs. "S" means it passed a proof-pressure test, a more rigorous check that currently grants a 10-year interval under 49 CFR 180.209 (this was raised from 7 years in an earlier version of the same rule — if you're reading a very old "S" stamp, or the recertifier mentions the 7-year figure, ask them directly which interval applies to your tank).
Where do I find the stamp?
Look at the collar (the metal ring around the valve) at the top of the tank. You'll see a month and two-digit year (e.g. "03 19"), sometimes followed by a letter. If there are several stamps, the most recent one is what governs — a tank can carry its original manufacture stamp plus one or more later requalification stamps as it ages.
What happens when it expires?
Refill and exchange stations are required by law to refuse an expired cylinder. You'll need to get it requalified (typically for a small fee at a propane retailer or hardware store that offers the service) or exchange it outright at a tank-exchange program, which supplies an already-certified tank in return for your old one.
Is this official guidance?
No. This tool summarizes typical, publicly stated DOT requalification intervals; it is not a substitute for reading your own cylinder or asking your requalifier. For the authoritative rule, see 49 CFR 180.209 at eCFR.gov.
Does my data get uploaded?
No. The page is fully client-side; nothing you enter leaves your browser. This page has no affiliate links and earns nothing from your answer.