Pocket Watch Database

Pocket Watch Key Sizes

Use the chart below to find the proper pocket watch key size to wind and set your early American movement. Please note the different size specifications utilized by various regions and match available keys accordingly. When in doubt, we recommend purchasing a set of keys, offering various sizes.

Pocket Watch Key Size Calculator

Carefully measure the width of your key square with a micrometer. Enter the measurement above to calculate the proper key size.

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Suggested Size:
English Square Size Key Size Indian Square Size
0.95mm 00 2.00mm
1.00mm 0 1.90mm
1.05mm 1 1.80mm
1.15mm 2 1.75mm
1.20mm 3 1.65mm
1.30mm 4 1.60mm
1.40mm 5 1.50mm
1.50mm 6 1.40mm
1.60mm 7 1.30mm
1.70mm 8 1.20mm
1.75mm 9 1.90mm
1.80mm 10 1.05mm
1.90mm 11 1.00mm
2.00mm 12 0.95mm