Date codes on everyday things

A lot of ordinary objects carry the date they were made, stamped somewhere you would not think to look. Two makers publish their schemes clearly enough to compute against: Zippo, on the bottom of every lighter since the mid-1950s, and Browning, in the serial number of every firearm since 1975.

Browning are unusually straight about the limits of their own records. Of pre-war production they write: “Year of manufacture on Pre-World War II production is strictly a guess.” That is a manufacturer describing its own published figures as guesswork, and this page shows you that sentence alongside the answer rather than quietly printing a year.

Zippo — a letter for the month, two digits for the year

Zippo publish the date code scheme themselves, in their own knowledge base, and their page will read a bottom stamp for you. Go there first. It is the maker's own answer, it is free, and it is more complete than this page could be.

Their wording and their example are not reproduced here. Zippo's terms restrict commercial use of their content and this site is going to carry advertising, so the letter-to-month mapping and the worked example have been withdrawn. Permission to describe the scheme is being asked for, and the day the answer is yes this comes back. Nothing about your lighter is in doubt — the stamp is almost certainly fine. What is missing is our licence to republish the key, not their scheme.

The two digits are the harder half, and this part is our own reading rather than theirs. Zippo have stamped lighters since 1932 and the code has changed form several times. Their own page dates the system to “the mid-1950s” and gives three logo eras for anything older — 1933–1954, 1954–1979 and 1980–2011. A lighter whose bottom stamp reads as recent under the current system, but whose logo is the block-letter style, is not a recent lighter — and the stamp alone will not tell you that.

What this page cannot do, and will not pretend to. Zippo's detailed era charts — “Classic Lighter Date Codes” and “Slim Lighter Date Codes” — are published as images, not text. They cannot be read by machine here, so they are not reproduced and not guessed at. For a lighter older than the current lettered system, go and look at Zippo's own page and read the charts yourself.

Browning — a cipher where letters stand for digits

Browning date your firearm themselves, from the serial number, on their own site. That is the place to go, and it costs nothing.

The cipher itself is not reproduced here. From 1975 Browning encode the date as a two-character code, and the key to it is short enough that printing it would be printing the scheme. Their terms forbid commercial use of their content without written permission, and this site is going to carry advertising, so it has been withdrawn along with the decoder that used it. Permission is being asked for. One thing worth knowing before you go, because it is ours and not theirs: the serial number restarts at 01001 every year, so the digits in front of the date code are a count, not a date.

Unusually for this site, both of these resolve cleanly. Two digits normally leave a century open — that is what makes half the music pages here show several readings. Not so here: a Zippo 19yy needs yy ≥ 32 because the company began in 1932, and 20yy needs yy ≤ 26 because later has not happened. Those ranges cannot overlap. The same holds for Browning from 1975. So the year was never the ambiguous part on this page, which is most of why losing these two schemes costs the reader so little: the makers answer it themselves, and they answer it exactly.

That cipher was checked, not assumed. It appears on 32 of Browning's 53 model pages and is identical on every one of them. The parser stops with an error if a second, different cipher ever turns up, because the page treats it as universal and that claim has to stay true.

Before 1975, it is per-model tables — and Browning say so

Older firearms are dated from a table specific to the model. There are 40 of those tables with 120 year rows between them, taken from Browning's own model pages. Four carry a warning from Browning themselves, quoted here verbatim:

And on the index page, covering the whole scheme:

“While every effort has been made to ensure that the information provided on serial numbers and dates of manufacture are accurate, records on early production models such as the Auto-5 and Superposed shotguns were not included due to the complexity of numbers, models and grades offered.”

The ones that publish nothing usable

Fifteen makers across lighters, tools, firearms, cameras and heating were checked, with robots.txt read and honoured on every one. None refused us.

The sweep missed Zippo, and here is exactly why

This is the second time a sweep on this site has come back empty for a maker who plainly does publish, and both times the reason was checkable. It is worth setting out, because it is the honest measure of what a “nothing found” is worth.

Adding “date your” promptly matched update-your-details — up-date-your — which is the seventh time on this site a search pattern has matched a word sitting inside another word. It is fixed with word boundaries, and the fix was verified by compiling the pattern out of the file rather than retyping it into a test.