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Appliance Age Finder

How to read an appliance serial number

Appliance serial numbers are not random. Most encode a date, and once you know the four patterns manufacturers actually use, most labels become readable.

There are only a handful of patterns

Across the ten brand families we cover, almost every serial number follows one of four shapes. Recognising which one you are looking at is most of the work.

  • Letter-prefix with week: a plant letter, a year character, then two digits for the production week. Whirlpool and everything it builds. Precise to the week.
  • Two letters for month and year: the first letter is the month, the second is the year. GE and North American Hotpoint. Precise to the month, but the year letter repeats.
  • Positional with a single year digit: fixed positions for plant, product, the last digit of the year, and the week. Frigidaire and Electrolux. Precise to the week, but the decade is missing.
  • A separate date field: the date is not in the serial at all but in a second number on the plate. Bosch's FD number. Precise to the month, and unambiguous.

Why letters instead of digits

Letters compress. A single character can carry a year, which keeps the serial short enough to stamp on a plate. The cost is that the alphabet runs out and the codes have to repeat — every twelve years for GE, twenty-four for legacy Maytag, thirty for Whirlpool.

Manufacturers also drop characters that are easily misread. Maytag's alphabet excludes I and O because they look like 1 and 0. GE uses only twelve letters — A, D, F, G, H, L, M, R, S, T, V, Z — chosen to be visually distinct from each other. If you think you have read a GE serial starting with B or E, look again.

The characters that catch people out

Five pairs cause almost all transcription errors: O and 0, I and 1 and L, S and 5, B and 8, and Z and 2. On a stamped metal plate under kitchen lighting, these are genuinely hard to tell apart.

Our decoder flags these rather than fixing them. If a character is ambiguous and changing it would change the decoded date, we ask you to confirm it instead of quietly picking one. Silently substituting a character is how a decoder produces a confident wrong answer.

What to do when nothing matches

If a serial does not decode, work through four possibilities in order. First, a character has been misread — this is by far the most common. Second, the serial was copied from the wrong label, such as the energy guide or a shipping carton. Third, the appliance predates the documented system. Fourth, it uses a regional format that has not been documented publicly.

A decoder that always returns an answer is not being helpful. Ours returns nothing when nothing fits, and tells you which of those four it is likely to be.

Last reviewed 29 July 2026.

Common questions

Can I work out the age from the model number instead?
Not directly. The model number identifies the product line and its production era, which helps narrow a repeating serial code down to the right decade, but it does not carry a build date of its own.
Why do some tools give one year and yours gives four?
Because for several formats, four years genuinely fit. A tool showing one year for a GE serial has picked one and not told you the others exist. We would rather show the shortlist and explain how to narrow it.

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