MM to Inches Fraction Chart12mm, 32mm & Printable 1/64" Reference

Convert millimeters to decimal inches and nearest tape-measure fractions. Use decimal inches for exact calculations and the fraction column for tape-measure or shop-floor reference.

15mm
0.5906 in
about 19/32 in
12mm
0.4724 in
about 15/32 in
8mm
0.3150 in
about 5/16 in
3mm
0.1181 in
about 1/8 in

Use the decimal value for machining or CAD. Use the nearest fraction when reading a tape measure, matching hardware, or marking a quick workshop cut.

Accurate - 25.4mm = 1"
Fractions - nearest 1/64"
Printable - Free PDF
⚡

Quick Converter Tool

Millimeters to inches in real-time, plus a reverse checker.

Example: 25.4 (Exactly 1 inch)

1.0000"

Approx: 1.0000" (1/1")

Quick references:
=
0.00 mm

Exact Formula

inches = mm ÷ 25.4

1 inch is defined as exactly 25.4 millimeters.

Exact MM vs Fractional Inch: What Changes?

Millimeters convert to exact decimal inches by dividing by 25.4, but most rulers, tape measures, drill bits, and hardware labels use fractional inch sizes. That means a value like 12mm has an exact decimal result (0.4724") and a practical nearest fraction (15/32"). For parts labeled with nominal sizes, always check the actual measured diameter or thickness before choosing a fraction.

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MM to Inches Conversion Chart

Range: 1-100mm • Precision: 3 decimal places • Fractions: 1/32"

Millimeters (mm)Inches (Decimal)Inches (Fraction)
10.0391/32
20.0793/32
30.1181/8
40.1575/32
50.1973/16
60.2361/4
70.2769/32
80.3155/16
90.35411/32
100.39413/32
110.4337/16
120.47215/32
130.5121/2
140.5519/16
150.59119/32
160.6305/8
170.66921/32
180.70923/32
190.7483/4
200.78725/32
210.82713/16
220.8667/8
230.90629/32
240.94515/16
250.98431/32
261.0241 1/32
271.0631 1/16
281.1021 3/32
291.1421 5/32
301.1811 3/16
311.2201 7/32
321.2601 1/4
331.2991 5/16
341.3391 11/32
351.3781 3/8
361.4171 13/32
371.4571 15/32
381.4961 1/2
391.5351 17/32
401.5751 9/16
411.6141 5/8
421.6541 21/32
431.6931 11/16
441.7321 23/32
451.7721 25/32
461.8111 13/16
471.8501 27/32
481.8901 7/8
491.9291 15/16
501.9691 31/32
512.0082
522.0472 1/16
532.0872 3/32
542.1262 1/8
552.1652 5/32
562.2052 7/32
572.2442 1/4
582.2832 9/32
592.3232 5/16
602.3622 3/8
612.4022 13/32
622.4412 7/16
632.4802 15/32
642.5202 17/32
652.5592 9/16
662.5982 19/32
672.6382 5/8
682.6772 11/16
692.7172 23/32
702.7562 3/4
712.7952 25/32
722.8352 27/32
732.8742 7/8
742.9132 29/32
752.9532 15/16
762.9922 1/1
773.0313 1/32
783.0713 1/16
793.1103 1/8
803.1503 5/32
813.1893 3/16
823.2283 7/32
833.2683 9/32
843.3073 5/16
853.3463 11/32
863.3863 3/8
873.4253 7/16
883.4653 15/32
893.5043 1/2
903.5433 17/32
913.5833 19/32
923.6223 5/8
933.6613 21/32
943.7013 11/16
953.7403 3/4
963.7803 25/32
973.8193 13/16
983.8583 27/32
993.8983 29/32
1003.9373 15/16

Formula: inches = mm ÷ 25.4

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File Details

Rows

100

Range

1-100

PDF FILE SIZE

≈0KB

Quality

300 DPI

Classroom fraction pack

Need classroom-ready fraction charts?

Get a free preview of our fraction and decimal printable pack for students, worksheets, and quick reference.

Printable MM to Inches Chart Preview

Preview the printable mm to inches chart before downloading. See exactly how the conversion table and workshop-ready layout will look when printed.

MM to Inches Chart printable conversion chart preview
Download-ready preview with watermark protection. Useful for workshop, kitchen, classroom, and quick wall reference use.

The "Tape Measure" Challenge: Decimals to Fractions

Converted 10mm to 0.3937" but can't find it on your ruler? Here is how to bridge the gap.

Reading the Increments

Most US tape measures use 1/16" increments. For precision conversions, you need to find the nearest fraction:

  • 0.0625" 1/16"
  • 0.1250" 1/8"
  • 0.2500" 1/4"
  • 0.3750" 3/8" (Close to 10mm!)
  • 0.5000" 1/2"

Pro Tip: The 10mm Hack

If you are working in a shop and need a quick match for 10mm, it is almost exactly 25/64". However, most people use 3/8"as a "close enough" substitute for non-critical work, though it is slightly smaller than 10mm.

Fastener Cross-Reference (Metric to SAE)

Trying to match a metric bolt to an imperial wrench? Use these common equivalents.

Common Bolt Substitutes

6mm→1/4" (slightly larger)Loose
8mm→5/16" (almost exact)Perfect
10mm→3/8" (slightly smaller)Tight
13mm→1/2" (almost exact)Excellent
19mm→3/4" (almost exact)Perfect

Engineering Warning

Never use an SAE wrench on a Metric bolt for high-torque applications (like engine work). The small difference (even 0.1mm) can cause the wrench to slip and round off the bolt head permanently.

Metric Dowel & Inch Bit Matching

DowelClosest BitFit
5mm3/16" (4.76mm)Too Tight
6mm15/64" (5.95mm)Snug/Perfect
8mm5/16" (7.94mm)Snug/Perfect
10mm25/64" (9.92mm)Very Snug

How to Use This Chart Effectively

Master millimeter to inches conversions with our comprehensive workshop guide.

Reading Decimals

Charts display up to 4 decimal places. For general fabrication, 3 places (0.XXX) is the industry standard.

Finding Fractions

Fractions are rounded to the nearest 1/64". Use these for marking workpieces with standard tape measures.

Printing for the Shop

Always print at 100% scale. We recommend laminating these charts to protect them from workshop grime.

Precision vs. Tolerance

🏠 Carpentry (±1/8")

Standard for framing and decks. Conversions can be rounded to the nearest 1/16".

🪑 Cabinetry (±1/64")

Furniture grade. Requires exact decimal-to-fraction matching for snug joinery.

Professional Applications

🪵

Woodworking

Essential for metric-plans or imported router bits. Convert bit depth instantly.

⚙️

Engineering

Critical for tolerance stack-ups where metric and imperial parts must interface.

🔧

Automotive

Match metric bolt heads to SAE sockets when the exact tool is missing.

The Math: How to Convert MM to Inches

Core Formula

Inches = MM ÷ 25.4

Established in 1959, the international inch is exactly 25.4mm. For precision, always divide by 25.4.

Need the reverse conversion or inch fractions?

Need the reverse direction? Use the Inches to MM chart when the source value starts in inches. If you need to turn a decimal inch result into a tape-measure fraction, use the Decimal to Fraction Inches chart or the Fraction to Decimal chart.

Inches to MM chartFraction to Decimal chartDecimal to Fraction Inches chart

Related Inch Fraction Charts

Need the reverse direction? Use the Inches to MM chart when the source value starts in inches. Working with drill bits or fasteners? Pair this chart with the Drill Bit Sizes chart and Wrench Size chart before choosing a shop reference.

Inches → MMWorkshop preset
Inches (fraction)Inches (decimal)MillimetersCentimeters
1/4"0.2506.350.64
1/2"0.50012.701.27
1"1.00025.402.54
1 1/2"1.50038.103.81
2"2.00050.805.08
2 1/2"2.50063.506.35
3"3.00076.207.62
4"4.000101.6010.16
5"5.000127.0012.70
6"6.000152.4015.24

Inches to MM

Imperial to metric conversions for hardware sizing and fabrication.

LengthWorkshopEngineeringhardwareengineering
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Frequently Asked Questions

What is mm to inches as a fraction?
To convert mm to inches as a fraction, first divide the millimeter value by 25.4 to get decimal inches, then round that decimal to the nearest common fraction such as 1/16", 1/32", or 1/64". This chart uses nearest 1/64" fractions for workshop and tape-measure reference.
What is 12mm to inches as a fraction?
12mm equals 0.4724 inches. Rounded to the nearest 1/64 inch, 12mm is about 15/32 inch. It is slightly under 1/2 inch.
What is 32mm to inches as a fraction?
32mm equals 1.2598 inches. Rounded to the nearest 1/64", 32mm is about 1 17/64". For exact work, use the decimal value; for layout or tape-measure marking, the nearest fraction is usually easier to read.
What is 15mm in inches?
15mm is 0.5906 inches. Rounded to a common tape-measure fraction, it is about 19/32 inch.
What is 8 mm to inches?
8mm is 0.3150 inches, which is close to 5/16 inch when rounded to a common fraction.
What is 1mm in inches?
1mm equals 0.03937 inches. As a practical fraction, it is close to 3/64 inch, but use the decimal value when precision matters.
What is 3mm in inches as a fraction?
3mm equals 0.1181 inches. Rounded to the nearest 1/64 inch, 3mm is about 1/8 inch. The exact 1/8 inch value is 0.125 inch, so use the decimal value for tight machining or hardware fit checks.
What is 13mm in inches or 32nds?
13mm equals 0.5118 inches. On a tape measure, that is about 1/2 inch, or roughly 16/32 inch. If you need a closer shop reference, 13mm is also close to 33/64 inch.
Should I use decimal inches or fractional inches for mm conversions?
Use decimal inches for machining, CAD, engineering drawings, and tolerance checks. Use fractional inches for tape measures, shop layout, woodworking marks, and quick hardware comparisons. If fit matters, confirm the actual measured size instead of relying only on the nearest fraction.
How do I convert millimeters to inches?
Divide the millimeter value by 25.4. For example, 12mm ÷ 25.4 = 0.4724 inches.
What is 15.87 mm to inches?
15.87mm is approximately 0.6248 inches, which is almost exactly 5/8 inch (0.625"). This is a critical conversion for matching metric machinery to imperial tooling.
What is 2.4 mm to inches?
2.4mm is approximately 0.0945 inches. In fractional inches, this is very close to 3/32" (0.0938").
Can I use an 8mm dowel in a 5/16 inch hole?
Yes. 5/16" is 7.94mm, which provides a very snug, almost perfect fit for an 8mm dowel. Confirm the actual dowel diameter if the joint fit is critical.
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