MM to Inches Converter
Updated Formulas shown
Divide millimeters by 25.4 to get inches: 10 mm = 0.3937 in, a hair over 3/8″. Switch the fraction readout to 1/32″ for drill bits and sockets.
Formula: inches = millimeters ÷ 25.4 (exact)
Common values: millimeters → inches
| millimeters | inches |
|---|---|
| 0.0393701 in≈ 1/16″ | |
| 0.0787402 in≈ 1/16″ | |
| 0.11811 in≈ 1/8″ | |
| 0.19685 in≈ 3/16″ | |
| 0.393701 in≈ 3/8″ | |
| 0.787402 in≈ 13/16″ | |
| 0.984252 in≈ 1″ | |
| 1.9685 in≈ 1 15/16″ | |
| 3.93701 in≈ 3 15/16″ | |
| 9.84252 in≈ 9 13/16″ | |
| 19.685 in≈ 19 11/16″ | |
| 39.3701 in≈ 39 3/8″ |
10 mm in every length unit
- 1 cm
- 0.01 m
- 0.00001 km
- 0.393701 in
- 0.0328084 ft
- 0.0109361 yd
- 0.00000621371 mi
- 393.701 mil
- 10,000 µm
- 0.00000539957 nmi
How to convert millimeters to inches
- Type the value in millimeters into the converter (or into the right-hand box to go the other way).
- Divide by 25.4 to get inches.
- Round to the nearest tape-measure mark — the converter shows the nearest 1/16″ and feet-and-inches automatically.
Millimeter to inch formula
inches = millimeters ÷ 25.4 — 1 mm = 0.03937008 in. The factor is exact by definition (NIST SP 811), so any rounding comes only from how many decimals you keep.
mm to in conversion table
| mm | inches | nearest 1/16″ | nearest 1/32″ |
|---|---|---|---|
| 1 | 0.0394 | 1/16″ | 1/32″ |
| 2 | 0.0787 | 1/16″ | 3/32″ |
| 3 | 0.1181 | 1/8″ | 1/8″ |
| 4 | 0.1575 | 3/16″ | 5/32″ |
| 5 | 0.1969 | 3/16″ | 3/16″ |
| 6 | 0.2362 | 1/4″ | 1/4″ |
| 7 | 0.2756 | 1/4″ | 9/32″ |
| 8 | 0.315 | 5/16″ | 5/16″ |
| 9 | 0.3543 | 3/8″ | 11/32″ |
| 10 | 0.3937 | 3/8″ | 13/32″ |
| 11 | 0.4331 | 7/16″ | 7/16″ |
| 12 | 0.4724 | 1/2″ | 15/32″ |
| 13 | 0.5118 | 1/2″ | 1/2″ |
| 14 | 0.5512 | 9/16″ | 9/16″ |
| 15 | 0.5906 | 9/16″ | 19/32″ |
| 16 | 0.6299 | 5/8″ | 5/8″ |
| 17 | 0.6693 | 11/16″ | 21/32″ |
| 18 | 0.7087 | 11/16″ | 23/32″ |
| 19 | 0.748 | 3/4″ | 3/4″ |
| 20 | 0.7874 | 13/16″ | 25/32″ |
| 21 | 0.8268 | 13/16″ | 13/16″ |
| 22 | 0.8661 | 7/8″ | 7/8″ |
| 23 | 0.9055 | 7/8″ | 29/32″ |
| 24 | 0.9449 | 15/16″ | 15/16″ |
| 25 | 0.9843 | 1″ | 31/32″ |
| 26 | 1.0236 | 1″ | 1 1/32″ |
| 27 | 1.063 | 1 1/16″ | 1 1/16″ |
| 28 | 1.1024 | 1 1/8″ | 1 3/32″ |
| 29 | 1.1417 | 1 1/8″ | 1 5/32″ |
| 30 | 1.1811 | 1 3/16″ | 1 3/16″ |
| 31 | 1.2205 | 1 1/4″ | 1 7/32″ |
| 32 | 1.2598 | 1 1/4″ | 1 1/4″ |
| 33 | 1.2992 | 1 5/16″ | 1 5/16″ |
| 34 | 1.3386 | 1 5/16″ | 1 11/32″ |
| 35 | 1.378 | 1 3/8″ | 1 3/8″ |
| 36 | 1.4173 | 1 7/16″ | 1 13/32″ |
| 37 | 1.4567 | 1 7/16″ | 1 15/32″ |
| 38 | 1.4961 | 1 1/2″ | 1 1/2″ |
| 39 | 1.5354 | 1 9/16″ | 1 17/32″ |
| 40 | 1.5748 | 1 9/16″ | 1 9/16″ |
| 41 | 1.6142 | 1 5/8″ | 1 5/8″ |
| 42 | 1.6535 | 1 5/8″ | 1 21/32″ |
| 43 | 1.6929 | 1 11/16″ | 1 11/16″ |
| 44 | 1.7323 | 1 3/4″ | 1 23/32″ |
| 45 | 1.7717 | 1 3/4″ | 1 25/32″ |
| 46 | 1.811 | 1 13/16″ | 1 13/16″ |
| 47 | 1.8504 | 1 7/8″ | 1 27/32″ |
| 48 | 1.8898 | 1 7/8″ | 1 7/8″ |
| 49 | 1.9291 | 1 15/16″ | 1 15/16″ |
| 50 | 1.9685 | 1 15/16″ | 1 31/32″ |
| 55 | 2.1654 | 2 3/16″ | 2 5/32″ |
| 60 | 2.3622 | 2 3/8″ | 2 3/8″ |
| 65 | 2.5591 | 2 9/16″ | 2 9/16″ |
| 70 | 2.7559 | 2 3/4″ | 2 3/4″ |
| 75 | 2.9528 | 2 15/16″ | 2 15/16″ |
| 80 | 3.1496 | 3 1/8″ | 3 5/32″ |
| 85 | 3.3465 | 3 3/8″ | 3 11/32″ |
| 90 | 3.5433 | 3 9/16″ | 3 17/32″ |
| 95 | 3.7402 | 3 3/4″ | 3 3/4″ |
| 100 | 3.937 | 3 15/16″ | 3 15/16″ |
Metric sockets and wrenches: closest SAE size
| metric | inches | closest SAE | difference |
|---|---|---|---|
| 6 mm | 0.2362 | 1/4″ | +0.35 mm |
| 7 mm | 0.2756 | 9/32″ | +0.14 mm |
| 8 mm | 0.315 | 5/16″ | −0.06 mm |
| 9 mm | 0.3543 | 11/32″ | −0.27 mm |
| 10 mm | 0.3937 | 3/8″ | −0.48 mm |
| 11 mm | 0.4331 | 7/16″ | +0.11 mm |
| 12 mm | 0.4724 | 1/2″ | +0.7 mm |
| 13 mm | 0.5118 | 1/2″ | −0.3 mm |
| 14 mm | 0.5512 | 9/16″ | +0.29 mm |
| 15 mm | 0.5906 | 9/16″ | −0.71 mm |
| 16 mm | 0.6299 | 5/8″ | −0.13 mm |
| 17 mm | 0.6693 | 11/16″ | +0.46 mm |
| 18 mm | 0.7087 | 11/16″ | −0.54 mm |
| 19 mm | 0.748 | 3/4″ | +0.05 mm |
| 20 mm | 0.7874 | 13/16″ | +0.64 mm |
| 21 mm | 0.8268 | 13/16″ | −0.36 mm |
| 22 mm | 0.8661 | 7/8″ | +0.22 mm |
| 23 mm | 0.9055 | 7/8″ | −0.78 mm |
| 24 mm | 0.9449 | 15/16″ | −0.19 mm |
A negative difference means the SAE socket is smaller than the bolt head and won't fit. More than about +0.2 mm larger risks rounding the corners — use the right metric size.
Where mm-to-inch conversions matter
Plywood and sheet goods are made to metric thicknesses even when sold by fractional names: "3/4 inch" plywood is usually 23/32″ (18.3 mm), and imported Baltic birch is 18 mm (0.709″). Dado blades and router bits sized for a true 3/4″ (19.05 mm) leave a sloppy joint in either.
Drill bits: a 6 mm bit (0.236″) is the usual metric stand-in for 15/64″, and a 10 mm bit (0.394″) is close to 25/64″. For anchors, follow the size printed on the anchor package — the hole tolerance is tighter than the conversion error.
Related converters & calculators
- Inches to MM ConverterMultiply by 25.4, with a 1/64″ fraction chart.
- CM to Inches ConverterDivide by 2.54, with tape-measure fractions.
- Plywood CalculatorCalculate 4×8 or 4×10 sheets of plywood or OSB for subfloors, walls and roofs, with waste and cost.
- Inches to CM ConverterMultiply by 2.54 — fractions like 3 1/2 work too.
- Feet to Meters ConverterMultiply by 0.3048 (exact).
- Meters to Feet ConverterDivide by 0.3048, shown in feet and inches.
- CM to Feet and Inches ConverterHeight in cm to feet and inches.
- Feet and Inches to CM ConverterType 5'9" and get centimeters.
Frequently asked questions
What is 10 mm in inches?
10 mm = 0.3937 in, just over 3/8″ (0.375″). On a 1/32″ scale it rounds to 13/32″.
Is a 19 mm socket the same as 3/4 inch?
Almost: 3/4″ is 19.05 mm, only 0.05 mm larger, so the two are commonly swapped.
How many mm in an inch?
Exactly 25.4 mm.
What size is 18 mm plywood in inches?
18 mm = 0.709″, a little under 23/32″ (0.719″). It is the metric equivalent of US "3/4 inch" plywood.
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Estimates only. Check quantities with your supplier or contractor before ordering.