Singer Serial Number Prefix Chart
Single-Letter Prefixes (1900–1920s)
Single letters were assigned to major manufacturing plants. Elizabethport and Clydebank, the two largest factories, drew from a shared pool of letters rather than each running its own sequence.
| Prefix | Factory Location | Date Range |
| A | Podolsk, Russia | 1911 onward (est.) |
| B | Elizabethport, New Jersey, USA | 1904–1905 |
| C | Wittenberge, Germany | 1908 onward (est.) |
| D | Elizabethport, New Jersey, USA | 1908–1909 |
| E | Podolsk, Russia | 1908 onward (est.) |
| F | Clydebank (Kilbowie), Scotland | 1910–1920 |
| G | Elizabethport, New Jersey, USA | 1910–1924 |
| H | Elizabethport, New Jersey, USA | 1906–1907 (est.) |
| J | — not a valid single-letter prefix — | — |
| K | Elizabethport, New Jersey, USA | 1902–1903 |
| L | Elizabethport, New Jersey, USA | 1901 |
| M | Clydebank (Kilbowie), Scotland | 1900 (est.) |
| N | Elizabethport, New Jersey, USA | 1900 |
| P | Clydebank (Kilbowie), Scotland | 1900–1901 (est.) |
| R | Clydebank (Kilbowie), Scotland | 1902–1903 (est.) |
| S | Clydebank, Scotland (main run); Podolsk, Russia (~100 units) | 1906–1907 (est.) |
| T | Podolsk, Russia | 1906 onward (est.) |
| V | Clydebank (Kilbowie), Scotland | 1908–1909 (est.) |
| W | Bridgeport, Connecticut, USA | 1954 onward |
| X | Clydebank (Kilbowie), Scotland | 1919 onward (est.) |
| Y | Clydebank (Kilbowie), Scotland | 1925, but possibly as early as 1920 |
Two-Letter Prefixes (1920s–1960s+)
As production expanded globally, Singer moved to a two-letter prefix structure. Six of the twenty-two entries below needed a date correction; the rest of the original table’s factory assignments were accurate.
| Prefix Block | Factory Location | Start Year |
| AA to AT | Elizabethport, New Jersey, USA | 1924 |
| BA to BY | Elizabethport, New Jersey, USA | 1924 |
| CA to CY | Bogotá, Colombia | 1964 |
| DA to DY | Karachi, Pakistan | 1962 |
| EA to EY | Clydebank (Kilbowie), Scotland | 1935 (block allocated); ISMACS shows the ED sub-block actually issued from 1941 |
| FA to FY | Clydebank (Kilbowie), Scotland | 1935 |
| GA to GY | Clydebank (Kilbowie), Scotland | 1935 |
| HA to HY | Istanbul, Turkey | 1959 |
| JA to JE | Saint-Jean-sur-Richelieu, Quebec, Canada | 1924 |
| KA to KY | Buenos Aires, Argentina | 1959 |
| LA to LY | Taytay, Philippines | 1959 |
| MA to MY | Monza, Italy | 1935 |
| NA to NC | Anderson, South Carolina, USA | 1951 |
| ND to NY | Taichung, Taiwan | 1963 |
| PA to PY | Karlsruhe, Germany | 1954 |
| RA to RY | Campinas, Brazil | 1955 |
| SA to SN | Bonnières-sur-Seine, France | 1935 |
| SP to SY | Lima, Peru | 1963 |
| TA to TY | Utsunomiya, Japan | 1954 |
| VA to VY | Penrith, NSW, Australia | 1959 |
| WA to WY | Santiago, Chile | 1967 |
| YA to YY | Querétaro, Mexico | 1958–1959 |
