Where do these numbers come from?
- NISTSP 811 exact unit definitions (1 in = 25.4 mm, 1 lb = 453.59237 g)current edition
- NISTHandbook 44, weights and measurescurrent edition
- King Arthur BakingIngredient Weight Chart (kitchen tools)retrieved Oct 23, 2026
Checked Oct 23, 2026. 1 inch is exactly 25.4 mm (NIST SP 811), so 100 mm ÷ 25.4 = 3.937 in.
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33 mm = 1.2992 in
Worked example
33 ÷ 25.4 = 1.2992 inches. On a ruler marked in sixteenths, that is about 1 5/16″; in thirty-seconds, 1 5/16″; in sixty-fourths, 1 19/64″. The nearest 1/16 mark (1 5/16″ = 33.34 mm) is off by 0.34 mm.
33 mm is also 3.3 cm.
| Millimeters | Inches | Nearest 1/16 |
|---|---|---|
| 28 mm | 1.1024 | 1 1/8″ |
| 29 mm | 1.1417 | 1 1/8″ |
| 30 mm | 1.1811 | 1 3/16″ |
| 31 mm | 1.2205 | 1 1/4″ |
| 32 mm | 1.2598 | 1 1/4″ |
| 33 mm | 1.2992 | 1 5/16″ |
| 34 mm | 1.3386 | 1 5/16″ |
| 35 mm | 1.378 | 1 3/8″ |
| 36 mm | 1.4173 | 1 7/16″ |
| 37 mm | 1.4567 | 1 7/16″ |
| 38 mm | 1.4961 | 1 1/2″ |
Frequently asked questions
How many inches is 33 mm?
1.2992 inches, about 1 5/16″.
What fraction of an inch is 33 mm?
About 1 5/16″ to the nearest 1/32.