Sources & Method

How we work

Four steps behind every date

1

Collect

We start from transcriptions of Singer’s own records, not from copies of copies.

2

Cross-check

Every model fact is checked against a second source where one exists.

3

Show disagreement

Where sources differ we print both figures and mark them Sources vary.

4

Correct

Readers send paperwork and photos; we re-check and update the data.

Coverage

How complete is the serial data?

Not every factory’s ledgers survive or have been published. This is how the 65 prefixes break down.

51 prefixes with exact ledger ranges2 with year ranges from Singer’s summary table12 with the period of use only

Our sources

Who we rely on

ISMACS

Serial ledgers and model lists

The International Sewing Machine Collectors’ Society has transcribed Singer’s serial allotment ledgers, one table per prefix, and keeps a pre-1900 serial database and model list. It is the backbone of our lookup.

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Singer’s summary dating table

Year ranges by prefix

Singer’s own table of prefixes and years, as reproduced by ISMACS. We use it only where ledger rows aren’t available.

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singersewinginfo.co.uk

British series, models and factories

A detailed reference to Singer machines, especially the Kilbowie (Clydebank) series, model versions, motors and factory history.

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sewalot

Pre-1900 numbers and model histories

Alex Askaroff’s long-running site, used for pre-1900 serial ranges, model histories and practical advice.

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singer-featherweight.com

Featherweight timeline and care

Featherweight specialists whose timeline and FAQ we use for the 221 and 222K, including faceplates, cases and lubrication.

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Manuals, Wikipedia and restorers

Cross-checks and context

Singer instruction and service manuals, Wikipedia, and well-regarded restorers’ guides, each cited on the page where we use them.

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Known limitations

Post-1900 dates are the dates a batch of serial numbers was ALLOTTED (reserved in advance for a given model), not the date a machine was made. Numbers were pre-allocated in large batches, sometimes months or years before use, and some were never used. (singersewinginfo.co.uk)
Surviving batch-allocation records cover essentially only Elizabethport and Kilbowie. There is 'virtually no information' for Singer's other factories, and the records contain many errors, so use them with caution. (singersewinginfo.co.uk)
ISMACS describes its coarse factory tables as 'taken from Singer publications'. For Bonnieres, France, ISMACS says dating is approximate because no factory records are known to survive.
Allotments were not strictly in serial order by date. Ranges overlap between years (e.g., AJ, AK), some blocks were never assigned (AN-962755–999999, AP-911301–999999), and some rows are marked as skips or missing numbers.
Prefix letters were not issued in alphabetical order by date. ISMACS notes that the R series was issued before J, and V before F.
Serial number shows when the casting was numbered, not when the machine was sold. Machines could reach customers years later; wartime backlogs (WWII) are the classic example. (sewalot)
Pre-1900 machines sometimes carry two or three numbers. Sewalot says to date by the higher, longer number. ISMACS links the second number to Howe patent royalty and Combination-era accounting.
Sewalot: 'Please note this is only a guide, not gospel!'
Singer itself has withdrawn its dating and identification information from its website (per ISMACS). The current singer.com value page only says where to look for the number and points to online databases. I found no current official Singer dating table online.

We hold no number ranges for some prefixes (for example JA–JE, NA–NC and SA–SC), and no data for Singer’s Podolsk (Russia) or Monza (Italy) factories.

Rows with uncertain year boundaries were re-checked against the ISMACS ledger pages in September 2026. Model guides were expanded and re-checked in October 2026; corrections found during that review are reflected on the pages.

Corrections

Have a machine with original paperwork that contradicts a result? Send us a photo of the serial number and the document, and we’ll update the data.

Four steps behind every date

Collect

Cross-check

Show disagreement

Correct

How complete is the serial data?

Who we rely on

ISMACS

Singer’s summary dating table

singersewinginfo.co.uk

sewalot

singer-featherweight.com

Manuals, Wikipedia and restorers

Known limitations

Corrections

Main serial sources

History and care sources