Unit Converter

How to Use the Unit Converter

This unit converter tool supports five categories of measurements: Length, Weight, Temperature, Area, and Volume. Select a category using the tabs at the top, enter a value, choose the source and target units from the dropdown menus, and the conversion result appears instantly. Use the swap button to quickly reverse the conversion direction. All calculations are performed in your browser with no data sent to any server.

Supported Unit Categories

Length conversions cover metric units (mm, cm, m, km) and imperial units (inch, foot, yard, mile). Weight supports milligrams through metric tons plus ounces and pounds. Temperature converts between Celsius, Fahrenheit, and Kelvin. Area handles square millimeters through square kilometers, plus square inches, square feet, acres, and hectares. Volume includes milliliters, liters, and US customary units like gallons, cups, fluid ounces, pints, and quarts.

Conversion Accuracy

All conversions use precise conversion factors based on international standards. The tool displays results with up to 10 significant digits for normal values, and uses scientific notation for very small numbers. Temperature conversions correctly handle the offset between scales, not just multiplication factors. The real-time calculation updates as you type, making it easy to explore different values and compare results across unit pairs without manually clicking a convert button.

単位変換ツールの使い方

長さ・重さ・温度・面積・容量の5カテゴリをタブで切り替え、数値を入力して変換元・変換先の単位を選ぶだけです。 入れ替えボタンで変換方向を即座に反転できます。海外レシピの換算、輸入品のサイズ確認、 技術文書のヤード・ポンド法→メートル法変換などにご利用ください。

よくある落とし穴と対処 / Common Pitfalls

換算式の例 / Formulas

温度:  F = C × 9/5 + 32        K = C + 273.15
長さ:  1 inch = 2.54 cm (定義値)   1 mile = 1.609344 km
重さ:  1 lb = 453.59237 g (定義値)  1 oz = 28.3495 g
面積:  1 acre ≈ 4046.86 m2     1 ha = 10000 m2
容量:  1 US gal = 3.785412 L    1 US cup = 236.588 mL

変換例 / Examples

5 km → 3.107 mile        (ランニング距離)
350 °F → 176.7 °C        (オーブンレシピ)
2 lb → 907.2 g           (食材)
1500 sq ft → 139.35 m2   (海外物件の面積)

Why browser-only?

Unit conversion needs no server — the math is deterministic and the conversion factors are public standards. This tool ships all factors with the page and computes everything locally: no tracking of what you convert, no latency, and full offline support once loaded. Your measurements (which can reveal projects, recipes, or shipments you are working on) stay on your device.

換算係数は全てページに同梱されており、計算はブラウザ内で完結します。 入力した数値が外部に送信されることはなく、オフラインでも動作します。