Unit converter — cm to inches, kg to lbs and more

The cheat sheet: cm to inches, kg to lbs, °C to °F

These factors cover the overwhelming majority of real-world conversions. Every pair below is one tap in the unit converter, which spans length, weight, temperature, volume, speed and data in a single page.

• Length: 1 inch = 2.54 cm (exact) · 1 foot = 30.48 cm · 1 mile = 1.60934 km — all in the length converter.
• Weight: 1 kg = 2.20462 lb · 1 lb = 453.592 g · 1 oz = 28.3495 g.
• Temperature: °F = °C × 9/5 + 32 — so 0 °C = 32 °F and 37 °C = 98.6 °F.
• Volume: 1 US gallon = 3.78541 L · 1 L ≈ 33.814 US fl oz · 1 US cup = 236.588 mL.
• Speed: 1 mph = 1.60934 km/h · 1 knot = 1.852 km/h.

How to convert any unit in three steps

Open the unit converter and pick a category — length, weight, temperature, volume, speed or data. Choose the from and to units, say centimeters to inches, then type your value. The result updates as you type, and a swap button flips the direction in one tap.

What to expect: type 180 with cm → inches selected and you get 70.87 inches immediately, with the full-precision figure ready to copy. There is no convert button to press, no page reload and no account. The math runs entirely in your browser, so the numbers you enter never leave your device — and once the page has loaded, it keeps converting even with a flaky connection. For a longer walkthrough of every category, see the unit conversion guide.

Multiply or divide? The one rule behind every conversion

Almost every unit conversion is a single factor, and the direction follows one rule: converting to a smaller unit gives a bigger number, so you multiply; converting to a larger unit gives a smaller number, so you divide. An inch is larger than a centimeter, so cm → inches divides by 2.54 and inches → cm multiplies by 2.54. A pound is smaller than a kilogram, so kg → lb multiplies by 2.20462.

If your answer looks wrong, you almost certainly went the wrong way — 100 cm is about 39 inches, not 254. The everyday exception is temperature, which shifts as well as scales (see the FAQ below). And when you want to sanity-check a factor by hand, the free calculator is one tab away.

Metric vs imperial — where each shows up in real life

Most of the world — and all of science and medicine — runs on metric: meters, kilograms, Celsius. The United States (and partly the UK) runs daily life on imperial: feet and inches for height, pounds for weight, Fahrenheit for weather and ovens, miles for distance.

That split is exactly where conversions come from. A US recipe gives you cups and °F while your kitchen thinks in milliliters and °C. A shopping listing quotes screen size in inches and package weight in pounds. A health form asks for kg and cm when you only know lb and ft — the same units behind body mass index, covered in the BMI calculator post. Rather than memorizing both systems, keep the factors above for estimates and let the unit converter produce the exact figure.

Data, speed and area conversions people actually search

Beyond the classics, three families come up constantly. Data first: in decimal units 1 GB = 1,000 MB and 1 TB = 1,000 GB, but operating systems often report binary units (1 GiB = 1,024 MiB) — which is why a "500 GB" drive shows up as roughly 465 GiB. Internet speed is its own trap: connections are sold in megabits (Mbps) while downloads show megabytes (MB/s) — divide by 8, so 100 Mbps is about 12.5 MB/s.

Area rounds out the set: 1 m² ≈ 10.7639 ft², 1 hectare = 10,000 m², and 1 acre ≈ 4,046.86 m². All of these live in the same unit converter categories, so you never need a separate tool per family.

Quick math on the side — basic and scientific calculator

Some jobs need more than one factor. Scaling a recipe by 1.5, averaging three measurements, or chaining a conversion with a price — that is where the free calculator earns its place next to the converter. It covers everyday arithmetic plus a scientific mode, takes keyboard input, and runs in your browser with nothing to install.

Two neighbors handle what fixed factors cannot. Percentages have their own tool — the percentage calculator, covered in the percentage and discount guide. And money is not a fixed factor at all: the currency converter uses up-to-date rates fetched from live sources, so unlike cm-to-inches its answer changes daily — the live exchange rates post explains how. For time, the date difference calculator counts the days between any two dates.

Frequently asked questions