Convert 40 mm to inches | 40 mm ≈ 1 1/2" | Calculator

Quick Answer: 40 mm = 1.5748 inches ≈ 1 3764"

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Conversion Result
40 mm = 1.5748 inches

40 mm ≈ 1 12 in (error: 4.75%)

40 mm ≈ 1 58 in (error: 3.19%)

40 mm ≈ 1 916 in (error: 0.78%)

40 mm ≈ 1 3764 in (error: 0.21%)

40 mm ≈ 1 1/2" (error: 4.75%)

Quick calculation:

  1. 40 mm ÷ 25.4 = 1.5748"
  2. 1.5748 × 2 = 3.1 → round to 3
  3. Result: 3/2

1 1/2" / 4 cm on a Ruler

Imperial (inches)

1 1/2 in on a ruler 0 1 2 3 4 1 1/2 in

Metric (cm)

4 cm on a ruler 0 1 2 3 4 5 6 7 8 9 10 4 cm

The red markers show 40 mm as 1 1/2" (imperial) and 4 cm (metric).

Learn more about converting mm to fractional inches →

Similar MM to Inches Conversions

Values close to 40 mm for quick reference:

Millimeters Decimal Inches Fractional Inches
30 mm 1.1811″ 1 3/16″
32 mm 1.2598″ 1 17/64″
34 mm 1.3386″ 1 11/32″
36 mm 1.4173″ 1 27/64″
38 mm 1.4961″ 1 1/2″
40 mm 1.5748″ 1 37/64″
42 mm 1.6535″ 1 21/32″
44 mm 1.7323″ 1 47/64″
46 mm 1.811″ 1 13/16″
48 mm 1.8898″ 1 57/64″
50 mm 1.9685″ 1 31/32″

See Also

Frequently Asked Questions

How much is 40 mm in inches?

40 millimeters equals 1.5748" (exactly 40 ÷ 25.4 inches).

How do I convert 40 mm to inches?

Divide millimeters by 25.4: 40 ÷ 25.4 = 1.5748 inches.

Is the conversion exact?

Yes. 1 inch = 25.4 mm exactly (1959 International Yard and Pound Agreement). All values on this page use this exact factor.

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40 mm to inches — 1.5748"

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All unit conversions on CoolConversion use conversion factors defined or documented by internationally recognised standards bodies (such as ISO and NIST), including both SI and non-SI units.

Conversion factors verified against NIST, BIPM, ISO 80000-3 1 inch = 2.54 cm by international agreement (1959). Last reviewed: March 2026
Adilson Fernandes By Adilson Fernandes
Tiago Fernandes Reviewed by Tiago Fernandes