MM TO INCHES

Enter millimeters below for instant decimal and fractional inch results. Includes visual ruler and full reference table.

Millimeters (mm)

Enter mm above

⇄

Inches (in)

Result appears here

Visual Scale — 0 to 300 mm 0%

050mm100mm150mm200mm250mm300mm

—

Millimeters

—

Decimal Inches

—

Fraction (1/64")

—

Centimeters

Fractional Breakdown

// All precision levels — updates live as you type

Halves

—

1/2" precision

Rough carpentry

Quarters

—

1/4" precision

General woodwork

Eighths

—

1/8" precision

Standard hardware

Sixteenths

—

1/16" precision

Machined parts

Thirty-seconds

—

1/32" precision

Precision metal

Sixty-fourths

—

1/64" precision

Fine instruments

Conversion Formula

// Exact factor — defined by international standard since 1959

MM → Inches (Decimal)

inches = mm ÷ 25.4

1 inch = exactly 25.4 millimeters. Example: 100 mm ÷ 25.4 = 3.93701"

MM → Fractional Inches

nearest = round(decimal × denominator) ÷ denominator

For 1/16": decimal × 16 → round → divide by 16. Example: 10mm → 0.3937 × 16 = 6.3 → 6/16 = 3/8"

Mental Shortcut (±1.6% error)

inches ≈ mm ÷ 25 (quick estimate)

Divide by 25 for fast mental math. Exact answer is 1.6% smaller. Good for rough work.

Full Reference Table

// 1–300 mm — click any row to load in converter

MM	Decimal Inches	1/8"	1/16"	1/32"	1/64"	CM	Common Use

Frequently Asked Questions

// MM to inches conversion Q&A