Historical and technical guide

Zippo date codes: dots, bars, slashes, Roman and modern numbers

Browse the historical case code sequences, A–L month letters, Roman numerals, Slim exceptions and current two-digit year codes.

All illustrated examples and dated claims link back to their original documented references and named sources. Transitional dates are approximate unless explicitly supported.

Recorded historical details

1955: Historical dating note

A real 1955 Bradford example supplied by Terry Lyons documents a brass case with steel insert and provides a photographed dot-layout comparison.

1955: Canadian production note

Canadian hinge transition: five-barrel hinges with equal spacing are generally treated as production through 1955.

Terry Lyons photographic reference: a Bradford regular-size case shows the 1966 vertical bars pattern (4 left, 4 right), with associated insert front/back and chimney-top photographs. The insert may have been replaced; determine case and insert dates separately.

1974: Slim manufacturing note

“Bradford PA.” is stamped on the bottom.

1986: Historical dating note

January-June use backslashes; July-December use month letters plus Roman II.

1986: Slim manufacturing note

The new date-code system appears, showing month and year of manufacture.

2000: Historical dating note

January-February use XVI-only layout; from March a 2000 + XVI layout is used.

2000: Slim manufacturing note

Moonlight documents two different Slim bottom stamps for 2000. From 2000 onward the year is shown in Arabic numerals.

2000: Canadian production note

Canadian insert imprinting turns upright again around 2000.

Month letter reference (A–L)

Standard letter-month codes are paired with a valid year-code family. Readability and changeover periods matter.

Letter	Month
A	January
B	February
C	March
D	April
E	May
F	June
G	July
H	August
I	September
J	October
K	November
L	December

Regular case mark sequences

The left and right quantities below are recorded from the dating knowledge base; variants and corrections are displayed rather than silently merged.

dots

Year	Left	Right	Notes
1955	4	4	pat-pending
1956	3	4	pat-pending
1957	4	4	pat-removed
1958	4	4	—
1959	4	3	—
1960	3	3	—
1961	3	2	—
1962	2	2	—
1963	2	1	—
1964	1	1	—
1965	1	0	—

bars

Year	Left	Right	Notes
1966	4	4	—
1967	4	3	—
1968	3	3	—
1969	3	2	—
1970	2	2	—
1971	2	1	—
1972	1	1	—
1973	1	0	—

slashes

Year	Left	Right	Notes
1974	4	4	—
1975	4	3	—
1976	3	3	—
1977	3	2	—
1978	2	2	—
1979	2	1	corrected
1979	1	2	early-error
1980	1	1	—
1981	1	0	—

backslashes

Year	Left	Right	Notes
1982	4	4	—
1983	4	3	—
1984	3	3	—
1985	3	2	—
1986	2	2	January-June

Slim-specific dot sequences

Slim production has period-specific stamping differences; do not apply regular-case dot counts automatically.

Year	Left	Right	Variant
1957	4	4	—
1958	4	4	overlap
1958	4	3	overlap
1959	3	3	—
1960	3	2	—
1961	2	2	—
1962	2	1	—
1963	1	1	—
1964	1	0	—
1965	0	0	—

Roman numerals, 1986–2000

The regular Roman system begins during 1986; II applies after the July 1986 changeover, not the full year.

Numeral	Year
II	1986
III	1987
IV	1988
V	1989
VI	1990
VII	1991
VIII	1992
IX	1993
X	1994
XI	1995
XII	1996
XIII	1997
XIV	1998
XV	1999
XVI	2000

Modern numeric year codes, 2001–2026

Two-digit numeric year codes begin with 01 for 2001. The year 2000 uses Roman XVI, not 00. The current calendar year is applied when the site is rebuilt.

Code	Year
01	2001
02	2002
03	2003
04	2004
05	2005
06	2006
07	2007
08	2008
09	2009
10	2010
11	2011
12	2012
13	2013
14	2014
15	2015
16	2016
17	2017
18	2018
19	2019
20	2020
21	2021
22	2022
23	2023
24	2024
25	2025
26	2026

Evidence interpretation

primary: Direct date code, patent wording/layout or established bottom-stamp system.

secondary: Case or insert construction detail that can narrow a period.

supporting: Useful clue with known overlap; never enough for an exact date by itself.

reported: Collector-observed variation that should be treated cautiously until more evidence is available.

Incomplete stamps, replacement inserts, special commemorative markings and factory transitions require caution. This reference is a dating guide, not a stand-alone authenticity certificate.