Inches to MM

Inches to MM | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Math & Numbers
Input types: text, number
Output type: json
Sample coverage: 4
API ready: Yes

Overview

Quickly convert measurements from inches to millimeters with customizable decimal precision. This tool provides instant, accurate metric conversions, making it easy to translate imperial dimensions for engineering, manufacturing, and woodworking projects.

When to use

When translating imperial blueprints or technical drawings into metric units for manufacturing.
When sourcing hardware components like screws, bolts, or pipes that are specified in inches but need to fit metric assemblies.
When performing precise scientific or woodworking calculations that require exact millimeter values with custom decimal rounding.

How it works

1Enter the length value in inches into the input field.
2Adjust the decimal precision value to set the desired number of decimal places between 0 and 10.
3View the instantly calculated millimeter result in the output JSON block.

Use cases

Converting standard lumber dimensions from inches to millimeters for international woodworking projects.
Translating mechanical component specifications, like bearing diameters or thread sizes, for metric CNC machining.
Standardizing product dimension sheets for e-commerce platforms that require metric measurements.

Examples

1. Converting Hardware Bolt Diameter

Mechanical Engineer

Background

An engineer is working with a legacy machine design that specifies a bolt diameter of 0.375 inches, but the new manufacturing facility operates strictly in metric units.

Problem

Convert 0.375 inches to millimeters with high precision to ensure the replacement bolt fits perfectly.

How to use

Input '0.375' in the Inches field and set the Decimal Precision to 4.

{
  "inches": "0.375",
  "precision": 4
}

Outcome

The tool outputs a precise value of 9.525 millimeters.

2. Rough Woodworking Dimensioning

Woodworker

Background

A hobbyist woodworker is following a US-based plan that calls for a board thickness of 1.5 inches, but their local metric planer uses millimeters.

Problem

Convert 1.5 inches to millimeters, rounded to a single decimal place for quick workshop reference.

How to use

Input '1.5' in the Inches field and set the Decimal Precision to 1.

FAQ

How many millimeters are in one inch?

There are exactly 25.4 millimeters in one inch.

Can I control the rounding of the converted millimeter value?

Yes, you can configure the decimal precision from 0 up to 10 decimal places.

Does this tool support fractional inches?

You should input decimal values, such as 0.5 instead of 1/2, for the conversion.

What is the default decimal precision?

The default precision is set to 4 decimal places.

Is there a limit to the precision I can set?

Yes, the precision can be configured between 0 and 10 decimal places.

{
  "inches": "1.5",
  "precision": 1
}

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Converting Hardware Bolt Diameter

2. Rough Woodworking Dimensioning

FAQ

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