Unit Converter

Most conversions are one multiplication — with two exceptions worth understanding

Length, weight, speed, and data size all convert the same simple way: every unit has a fixed ratio to one base unit, and converting means multiplying into the base and dividing back out. A meter is the base for length, so a kilometer is 1,000 of them and an inch is exactly 0.0254 of one. To turn 5 inches into centimeters the tool multiplies 5 by 0.0254 to reach meters, then divides by 0.01 to reach centimeters. Because these ratios are fixed international definitions, the results are exact rather than approximate — an inch is defined as 0.0254 m, not rounded to it.

Two categories break that pattern, and they are the two people most often get wrong: data size, because "kilo" means two different things, and temperature, because the scales do not start from the same zero. Both are handled correctly here, and both are worth understanding because the mistakes are so common.

Kilobyte or kibibyte: the 2.4% that explains your "missing" storage

Everywhere except computing, "kilo" means exactly 1,000. A kilometer is 1,000 meters, a kilogram is 1,000 grams. But early computer memory was addressed in powers of two, and 2¹⁰is 1,024 — close enough to a thousand that engineers borrowed the word and called 1,024 bytes a "kilobyte." That shortcut has caused confusion ever since.

The gap looks small at one step — 1,024 versus 1,000 is 2.4% — but it compounds. At the megabyte it is about 4.9%, at the gigabyte about 7.4%, and at the terabyte roughly 10%. This is exactly why a drive sold as "500 GB" shows up as around 465 GB in your file manager: the manufacturer counts in decimal gigabytes (1,000³bytes) while the operating system counts in binary but still prints the label "GB." To end the ambiguity the international standard defined separate binary units in 1998 — kibibyte (KiB), mebibyte (MiB), gibibyte (GiB) — for the 1,024-based values, reserving KB, MB, and GB for true decimal thousands. This converter lists both so you are never silently converting with the wrong base; pick the decimal units for storage marketing and network speeds, the binary ones for RAM and what your OS reports.

Why temperature needs a formula, not a factor

You cannot convert Celsius to Fahrenheit by multiplying by a single number, and the reason is that the two scales do not agree on where zero is. With length, zero is zero in every unit — zero meters is zero feet — so one ratio does the whole job. Temperature scales were each anchored to different reference points: Celsius put zero at water's freezing point, Fahrenheit put it well below that. So converting needs two steps, a stretch and a shift: °F = °C × 9/5 + 32. The 9/5 accounts for Fahrenheit degrees being smaller, and the +32 realigns the zero points.

Kelvin is the scientific scale and behaves more simply because it uses the same degree size as Celsius — it just moves the zero all the way down to absolute zero, the coldest temperature physically possible, where molecular motion stops. That makes the conversion a pure offset: K = °C + 273.15. Because Kelvin has no negative values and no arbitrary zero, it is the scale physics equations are written in. The converter applies each of these formulas directly rather than pretending temperature is a scaling problem, which is why 100°C correctly returns 212°F and not some multiplied-out approximation.

Reading the result, and where precision really ends

The result is formatted to be read, not to fill a fixed number of decimal places. A clean answer shows cleanly — 100°C to Fahrenheit is 212, not 212.000000 — while small fractions keep enough significant digits to stay useful, and genuinely huge or tiny numbers switch to scientific notation so the box never fills with a wall of zeros. Clearing the input leaves the result blank rather than showing a misleading zero.

The honest limit on precision is not the conversion factors, which are exact, but the fact that all of this runs in binary floating-point arithmetic — the same reason 0.1 + 0.2 is famously not quite 0.3 on a computer. In practice the error lives far below any digit you would act on, so for schoolwork, recipes, workshop measurements, and everyday conversions the results are effectively exact. The one place to be careful is when a result feeds a regulated tolerance — dosages, structural loads, legal weights — where you should confirm against the governing standard rather than any general-purpose converter, this one included.

Everything is computed on your device

The converter needs no network. Every unit ratio and every formula lives in the page itself, so the arithmetic happens in your browser and nothing you enter — values, unit choices, or results — is sent to a server or stored between visits. Once the page has loaded it keeps working offline, and reloading simply starts fresh. It is a calculator that happens to run in a browser tab, not a service that watches what you convert.