Tinker Tools

Unit Converter Instant

Convert between units of length, weight, temperature, and shoe sizes. All calculations happen locally in your browser—fast, free, and private.

Enter a valid number

All Conversions for 1 m

Millimeter
1000 mm
Centimeter
100 cm
Meter
1 m
Kilometer
0.001 km
Inch
39.37007874 in
Foot
3.280839895 ft
Yard
1.093613298 yd
Mile
0.0006213711922 mi

How it works

1. Select Category

Choose from length, weight, temperature, or shoe sizes. Each category contains the most commonly used units for quick access.

4 Categories

2. Pick Units & Enter Value

Select your source and target units, then type a value. The conversion happens in real time as you type — no need to click a button.

Real-Time Results

3. View All Conversions

See your value converted to every unit in the category at once. The conversion table updates instantly, giving you a complete overview.

Full Overview

What is Unit Conversion?

Unit conversion is the process of transforming a measurement from one unit to another within the same dimension — length, weight, temperature, or any other physical quantity. The underlying value stays the same; only the scale changes. One meter is always 3.28084 feet, regardless of context. The math is straightforward multiplication or division by a constant factor, except for temperature, which uses linear formulas with offsets.

The need for unit conversion arises constantly in engineering, science, cooking, travel, and software development. An API might return distances in kilometers while your UI displays miles. A weight sensor might report grams while your database stores kilograms. CSS uses pixels, points, ems, and rems interchangeably depending on context. Having a fast, reliable conversion tool eliminates mental math errors and speeds up development.

This converter handles four common categories: length (metric and imperial), weight (metric and imperial), temperature (Celsius, Fahrenheit, Kelvin), and shoe sizes (US, EU, UK, and centimeter foot length). All calculations happen in your browser using standard conversion factors — no server calls, no rounding shortcuts.

Key Features and Benefits

  • Real-Time Conversion — Results update as you type — no need to click a button. This makes it easy to experiment with different values and see the results instantly. The conversion uses JavaScript's native floating-point arithmetic for fast, precise calculations.
  • Conversion Table View — See your value converted to every unit in the category simultaneously. Instead of switching between from/to pairs, the table gives you a complete overview in one glance. This is especially useful when you need to compare multiple units at once, like when checking both feet and yards for the same meter value.
  • Temperature Formulas — Temperature conversion is not a simple ratio — it requires specific formulas. Celsius to Fahrenheit uses F = C * 9/5 + 32. Celsius to Kelvin uses K = C + 273.15. The tool applies these exact formulas, not approximations, so you get precise results for scientific and engineering use.
  • Shoe Size Reference Table — Shoe sizes use different numbering systems across regions and there is no single mathematical formula that perfectly maps between them. The tool uses a curated reference table based on standard industry conversions for men's sizes across US, EU, UK, and centimeter foot length systems.
  • Swap Button for Quick Reversals — One click swaps the from and to units while preserving your input value. This is handy when you need to quickly check the reverse conversion — for example, after converting meters to feet, swap to see how many meters are in that number of feet.
  • Client-Side Processing — Every calculation runs in your browser. No data is sent to any server. The conversion factors are hardcoded constants based on international standards (SI units, NIST reference values). The tool works offline once the page has loaded.

How to Convert Units Online

  1. 1

    Select a Category

    Choose from Length, Weight, Temperature, or Shoe Size using the tab bar at the top. Each category loads its own set of units with appropriate defaults. For length, the default is meters to feet. For temperature, Celsius to Fahrenheit.

  2. 2

    Choose Your Units

    Use the dropdown selectors to pick the source unit (From) and target unit (To). For length, options include millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles. Use the swap button between the selectors to quickly reverse the direction.

  3. 3

    Enter a Value

    Type a number into the Value field. The result updates in real time as you type. You can enter integers, decimals, or negative numbers (negative numbers are valid for temperature conversions). The input accepts standard numeric notation.

  4. 4

    Read the Result and Conversion Table

    The converted value appears in the Result field with the target unit symbol. Below that, the conversion table shows your input value converted to every unit in the current category. The target unit is highlighted for quick reference.

  5. 5

    Try Shoe Sizes (Special Category)

    Switch to the Shoe Size tab for a lookup-based conversion. Select your size system (US, EU, UK, or cm), enter your size, and see the closest match across all systems. The full reference table below highlights your selected size for easy comparison.

Expert Tips for Unit Conversions

When converting between metric and imperial units, remember that the conversion factors are exact by definition. One inch is defined as exactly 25.4 millimeters. One pound is exactly 453.59237 grams. One mile is exactly 1,609.344 meters. These are not approximations — they are international agreements. Any rounding errors you see come from floating-point arithmetic in the calculator, not from imprecise conversion factors.

Temperature is the one category where conversion is not a simple multiplication. The Celsius and Fahrenheit scales have different zero points and different degree sizes. Kelvin shares the degree size with Celsius but starts at absolute zero (-273.15 C). A common mistake is trying to convert temperature differences the same way as absolute temperatures — a 10-degree Celsius difference equals an 18-degree Fahrenheit difference, but 10 C is not 18 F.

For shoe sizes, no universal standard exists. European sizes use the Paris point (2/3 cm per size), US sizes use the Brannock system, and UK sizes have their own scale. Even within a system, manufacturers vary. The conversion table gives you a reliable starting point, but always try shoes on or check the specific brand's size chart before buying, especially for online purchases.

If you are building software that needs unit conversions, store values in a single canonical unit internally (meters for length, grams for weight, Celsius for temperature) and convert only at the display layer. This avoids compounding rounding errors from repeated conversions. The same principle applies to databases — store in one unit, convert in the application or query output.

Related Tools

File Size Calculator

File size is another common conversion task — bytes to kilobytes, megabytes to gigabytes. The file size calculator handles both binary (1024-based) and decimal (1000-based) unit conversions, complementing this tool's physical unit conversions.

Time Zone Converter

Converting between time zones is conceptually similar to unit conversion but with the added complexity of daylight saving time rules. Use the time zone converter alongside this tool when working with international data that includes both measurements and timestamps.

BMI Calculator

The BMI calculator requires height and weight inputs that you may need to convert first. If your height is in feet/inches but the calculator expects centimeters, use the unit converter to get the right values before calculating your BMI.

These tools complement the unit converter for common calculation workflows. Convert your measurements here, check file sizes with the file size calculator, coordinate time zones for international teams, or prepare height and weight inputs for health calculators. Each tool handles one dimension precisely.

Frequently Asked Questions

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