Pocket Watch Database

Pocket Watch Mainsprings

Pocket Watch Mainspring Part Numbers, Sizes, & Types

The mainspring provides power to the mechanics of the watch. When a mainspring breaks or no longer offers enough energy for precise timekeeping, a replacement will be required. Measure the dimensions of the old mainspring using a micrometer, and use the chart below to find proper replacement for any American movement. Note: Using proper tools for mainspring installation is highly advised.

Manufacturer   Movement Size   Part Number   Alt. Part Number   Length (in)   Width (mm)   Thickness [Strength] (mm)   End   Purchase on eBay
Elgin 18 812 21.5 2.90 0.22
Double Brace and Hole
Elgin 18 812 21.5 2.90 0.23
Double Brace and Hole
Elgin 16 817 21.5 2.65 0.185
Double Brace and Hole
Elgin 16 817 21.5 2.65 0.20
Double Brace and Hole
Elgin 16 817 21.5 2.65 0.205
Double Brace and Hole
Elgin 16 6164 24 2.90 0.19
Double Brace and Hole
Elgin 12 2339 6093 20 2.00 0.19
Double Brace and Hole
Elgin 12 2874 20.25 1.60 0.185
Double Brace and Hole
Elgin 6 824 17.5 1.90 0.18
Double Brace and Hole
Elgin 0 2097 6095 16.5 1.70 0.14
Double Brace and Hole
Elgin 3/0 2097 6095 16.5 1.70 0.14
Double Brace and Hole
Elgin 4/0 4789 6096 15 1.90 0.11
Double Brace and Hole
Elgin 5/0 2890 6098 11.5 1.25 0.115
Double Brace and Hole
Elgin 6/0 2890 6098 11.5 1.25 0.115
Double Brace and Hole
Elgin 8/0 5219 6002 12 1.65 0.10
Double Brace and Hole
Elgin 10/0 1957 6009 9.75 1.25 0.12
Double Brace and Hole
Elgin 15/0 5550 6003 12 1.27 0.10
Double Brace and Hole
Elgin 19/0 6330 11.75 1.53 0.0725
Double Brace and Hole
Elgin 20/0 5015 6100 8.5 1.15 0.09
Double Brace and Hole
Elgin 21/0 5327 6004 9.25 1.27 0.09
Double Brace and Hole
Elgin 21/0 6246 9.5 1.53 0.0725
Double Brace and Hole
Hamilton 18 15 718013 21.25 2.85 0.205
T-End
Hamilton 16 534B 718050 23.5 0.30 0.155
Double Brace and Hole
Hamilton 16 318 718043 21.25 2.85 0.2
T-End
Hamilton 16 317 718042 21.25 2.85 0.19
T-End
Hamilton 16 317 718041 21.25 2.85 0.18
T-End
Hamilton 16 534 718047 20.75 2.85 16
Double Brace and Hole
Hamilton 12 1228 718071 21.25 1.70 0.18
Double Brace and Hole
Hamilton 12 3028 21.25 1.70 0.18
Double Brace and Hole
Hamilton 6/0 1721 718200 11.25 1.35 0.135
T-Brace
Hamilton 6/0 1921 11.25 1.35 0.135
T-Brace
Hamilton 6/0 2321 718201 11.5 1.35 0.12
T-End
Hamilton 6/0 2521 718202 11.5 1.35 0.12
T-End
Hamilton 6/0 2621 718203 11 1.35 0.12
T-Brace
Hamilton 8/0 7221 718272 13.5 1.40 0.095
T-Brace
Hamilton 8/0 7221 718271 13.5 1.40 0.085
T-Brace
Hampden 18 1696 21.75 2.90 0.21
T-End
Hampden 18 1696 21.75 2.90 0.23
T-End
Hampden 16 2696 21.75 2.90 0.19
T-End
Hampden 16 3696 21.5 2.70 0.2
T-End
Hampden 16 3696 21 2.70 0.19
T-End
Hampden 16 4697 21 2.70 0.18
T-Brace
Hampden 16 5697 21.5 2.70 0.165
Hole
Hampden 12 6696 18.5 1.80 0.18
T-End
Hampden 12 12696 19 1.40 0.175
T-End
Hampden 6 8696 16.25 1.75 0.165
T-End
Hampden 3/0 9696 13 1.40 0.16
T-End
Hampden 8/0 15696 8.25 1.25 0.14
T-End
Howard 18 55 23.5 2.80 0.205
Hole
Howard 16 328 21.5 2.75 0.165
Hole
Howard 16 329 21 2.70 0.18
T-End
Howard 12 552 19.5 1.80 0.15
Hole
Howard 12 553 19 1.80 0.16
T-End
Howard 10 796 16 1.50 0.15
Hook
Illinois 18 47302 53 21.5 2.90 0.21
T-End
Illinois 18 47303 21.5 2.90 0.22
T-End
Illinois 16 47309 27 3.00 0.155
Double Brace and Hole
Illinois 16 47315 20.5 2.70 0.185
T-Brace
Illinois 16 47317 573 20.5 2.70 0.21
T-Brace
Illinois 16 47321 1770 22.5 2.70 0.18
T-Brace
Illinois 16 47326 22.5 2.70 0.175
Motor Barrel Brace
Illinois 16 47327 22.5 2.70 0.175
Motor Barrel Brace
Illinois 16 47331 22.5 2.70 0.175
Double Brace and Hole
Illinois 16 47333 124 20.5 2.90 0.2
T-End
Illinois 16 47334 20 2.50 0.21
T-End
Illinois 13 47337 1845 18.5 1.35 0.18
Motor Barrel Brace
Illinois 12XT 47337 1845 18.5 1.35 0.18
Motor Barrel Brace
Illinois 12 47343 18.5 2.00 0.17
T-Brace
Illinois 12 47344 1236 18.5 2.00 0.18
T-Brace
Illinois 0 47358 981 13 1.70 0.13
T-End
Illinois 3/0 47358 981 13 1.70 0.13
T-End
Illinois 6/0 47364 1422 10.5 1.20 0.13
T-Brace
Illinois 6/0 47371 12.5 1.40 0.11
T-Brace
Illinois 18/0 47383 10.5 1.20 0.09
T-Brace
New York Standard 18 2190 20 2.90 0.23
T-End
New York Standard 16 3349 20.5 2.45 0.22
T-End
New York Standard 16 3196 20.5 2.45 0.22
T-End
New York Standard 12 4284 18 1.83 0.2
T-End
New York Standard 12 4144 19 1.90 0.22
T-End
New York Standard 10 7080 17 1.50 0.19
Tongue
Rockford 18 644 22 2.90 0.22
T-End
Rockford 16 822 20.5 2.70 0.205
T-End
Rockford 12 932 18.75 2.00 0.172
T-End
Rockford 0 1077 13.75 1.70 0.14
T-End
South Bend 18 19528 21.5 2.95 0.195
T-End
South Bend 16 17528 20.5 2.55 0.2
T-End
South Bend 16 27528 21.75 2.80 0.19
T-End
South Bend 12 55528 19 1.98 0.175
T-End
Seth Thomas 18 536 141 21.5 3.30 0.19
T-Brace
Seth Thomas 18 729 141 30 3.30 0.22
T-Brace
Waltham 18 2203 21 2.90 0.225
T-End
Waltham 18 2203 21 2.90 0.22
T-End
Waltham 18 2203 21 2.90 0.215
T-End
Waltham 18 2222 25 3.30 0.16
Hole
Waltham 18 2205 21 3.00 0.22
T-End
Waltham 16 2208 21 2.30 0.22
T-End
Waltham 16 2227 2267 25 2.80 0.18
Hole
Waltham 16 2218 2267 25 2.80 0.19
Hole
Waltham 16 2247 2268 19.5 2.60 0.17
Double Brace and Hole
Waltham 14 2234 19 1.30 0.175
Hole
Waltham 10 2234 19 1.30 0.175
Hole
Waltham 14 2252 2269 19 1.62 0.17
Hole
Waltham 12 2224A 2279 19.25 2.15 0.16
Hole
Waltham 12 2224A 2279 19.5 2.15 0.15
Hole
Waltham 12 2224A 2279 19.5 2.15 0.14
Hole
Waltham 6 2215 16 1.90 0.21
T-End
Waltham 6 2217 16 1.90 0.19
T-End
Waltham 6 2219 16 2.10 0.15
Hole
Waltham 0 2220 16 1.50 0.15
Hole
Waltham 0 2228 15 1.70 0.13
Hole
Waltham 0 2230 2278 15 2.05 0.14
Hole
Waltham 0 2230 2278 15 2.05 0.13
Hole
Waltham 6/0 2226 2276 13.5 1.50 0.12
Hole
Waltham 6/0 2235 13.5 1.30 0.13
Hole
Waltham 6/0 2226 9.5 1.50 0.12
Hole
Waltham 12 2237 2269 19.25 1.70 0.165
Hole
Waltham 7.25L 2238 2274 12 1.30 0.11
Hole
Waltham 6.5L 2239 2272 9.75 1.05 0.1
Hole
Waltham 4L 2240 2260 8 1.10 0.09
Hole
Waltham 7.5L 2250 11.25 1.15 0.11
Double Brace and Hole
Waltham 8.75L 2242 8.5 1.40 0.085
Hole
Waltham 7.5L 2234 2266 13 1.12 0.1
Hole
Waltham 6.75L 2244 2261 7.75 1.20 0.065
Hole
Waltham 16 2246 17 1.50 0.165
Double Brace and T
Waltham 6/0 2248 2265 12 1.50 0.1
Double Brace and Hole
Waltham 6/0 2248 2265 12 1.50 0.11
Double Brace and Hole
Waltham 6.75L 2249 2263 7.5 1.15 0.065
Tongue
Waltham 7L 2249 2263 7.5 1.15 0.065
Tongue
Waltham 6.75L 2251 2262 9.5 1.30 0.08
Double Brace and Hole
Waltham 7L 2251 2262 9.5 1.30 0.08
Double Brace and Hole
Waltham 8.75L 2253 9 1.30 0.085
Double Brace and Hole
Waltham 8L 2253 9 1.30 0.085
Double Brace and Hole
Waltham 37 2232 2280 28.25 4.50 0.23
Hole
Waltham 37 2232 2280 28.25 4.50 0.22
Hole
Waltham 22 2245 2275 25 5.40 0.22
Double Brace and T
Data Source: BestFit Mainspring Chart