Inch Converter

Convert inches to and from centimeters, millimeters, feet, meters, yards, micrometers, and miles. Bidirectional conversion with adjustable precision and inch-fraction reference table.

About the Inch Converter

The inch is a foundational unit in the US customary and imperial measurement systems. Whether you are working on a woodworking project that uses fractional inches, reading product dimensions listed in centimeters, or converting blueprint measurements to metric, you need a reliable inch converter that handles multiple target units at once.

This tool converts inches to and from seven different length units — millimeters, centimeters, meters, feet, yards, micrometers, and miles. Choose your conversion direction, enter a value, and see results in all units simultaneously. Adjustable decimal precision lets you match the accuracy your task demands.

A built-in inch-fraction to millimeter reference table covers every common fraction from 1/64 to 1 inch, making this especially valuable for machinists, carpenters, and engineers who routinely work with fractional inch measurements. It also helps students and technicians verify conversion steps without switching between multiple separate tools during shop, classroom, and field workflows daily.

Why Use This Inch Converter?

Unlike single-direction converters, this tool works bidirectionally — convert inches to centimeters or centimeters back to inches with one click. It shows all seven unit conversions at once, so you never need to run multiple searches. The adjustable precision and fraction reference table make it equally useful for rough carpentry estimates and precision machining tolerances.

How to Use This Calculator

  1. Select conversion direction: Inches → Other Unit or Other Unit → Inches.
  2. Choose your target unit from the dropdown (cm, mm, m, ft, yd, µm, or mi).
  3. Enter the numeric value in the input field.
  4. Adjust decimal places if you need more or less precision.
  5. Use preset buttons for common values like 12 inches (1 ft) or 36 inches (1 yd).
  6. Review all conversions in the output grid and the full all-units table.
  7. Expand the inch fractions table for a machinist-ready fraction-to-metric reference.

Formula

Inches to Millimeters: mm = in × 25.4 Inches to Centimeters: cm = in × 2.54 Inches to Meters: m = in × 0.0254 Inches to Feet: ft = in / 12 Inches to Yards: yd = in / 36 Inches to Micrometers: µm = in × 25,400 Inches to Miles: mi = in / 63,360

Example Calculation

Result: 30.48 cm

12 inches equals exactly 1 foot. Converting to centimeters: 12 × 2.54 = 30.48 cm. This is also 304.8 mm, 0.3048 m, and 1/3 of a yard.

Tips & Best Practices

The History of the Inch

The inch traces back to at least the 7th century, originally defined as the width of a man's thumb or three barleycorns laid end to end. Over centuries, different countries had slightly different inch lengths. The international agreement of 1959 standardized the inch at exactly 25.4 millimeters, finally resolving discrepancies between the US, UK, and Commonwealth nations.

Inches in Everyday Life

Screen sizes (TVs, phones, monitors) are measured diagonal in inches. Tire rim diameters use inches. Pipe sizes, bolt sizes, lumber dimensions (nominal vs. actual), and screw gauges in the US all rely on inches. Even in metric countries, screen sizes are conventionally quoted in inches.

Precision Considerations

For general purposes, two decimal places suffice (e.g., 2.54 cm per inch). Machining tolerances may require four or more decimals. CNC programs and engineering drawings often specify dimensions in thousandths of an inch ("thou" or "mil"), where 1 mil = 0.001 inch = 0.0254 mm.

Frequently Asked Questions

How many centimeters are in an inch?

Exactly 2.54 centimeters. This is an exact, defined value — the international inch has been precisely 25.4 mm since 1959.

How do I convert inches to feet?

Divide the number of inches by 12. For example, 66 inches ÷ 12 = 5.5 feet, which is 5 feet 6 inches.

What is the difference between a US survey inch and an international inch?

The US survey inch was 1/39.37 of a meter (≈25.4000508 mm), while the international inch is exactly 25.4 mm. The survey inch was officially deprecated by NIST in 2023.

How do I read fractional inches?

Fractional inches use powers of 2 as denominators: 1/2, 1/4, 1/8, 1/16, 1/32, and 1/64. Each step halves the previous division. For example, 3/8″ means three of the eight equal parts of an inch.

Why are inches still used instead of metric?

The US, Liberia, and Myanmar have not fully adopted the metric system. In the US, inches are deeply embedded in construction, manufacturing standards, and everyday life. Many industries use both systems in parallel.

How many inches are in a mile?

There are 63,360 inches in a mile. One mile = 5,280 feet × 12 inches/foot = 63,360 inches.

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