$ conv --units
Math and conversionUnit Converter Online
Eight quantities, with the value converted into every unit at once — from inch to alqueire, from Celsius to Kelvin, from MB to MiB.
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3.28084 pé
1 m = 3.28084 pé
The same value in every unit
- millimetre
- 1,000 mm
- centimetre
- 100 cm
- metre
- 1 m
- kilometre
- 0.001 km
- inch
- 39.37008 pol
- foot
- 3.28084 pé
- yard
- 1.093613 jd
- mile
- 0.0006213712 mi
- nautical mile
- 0.0005399568 M
One conversion, every answer
Most converters make you pick the target unit before showing anything — and you only find out you needed a different one afterwards. Here, besides the highlighted "from/to" pair, the page shows the same value in every unit of the quantity. Typing 5 metres returns, in one go, what that is in centimetres, inches, feet, yards and miles.
The eight quantities
- Length — from millimetre to nautical mile, with inch, foot and yard for screen sizes, heights and imported materials.
- Mass — includes the arroba (15 kg), the unit in which cattle and coffee are still traded in Brazil.
- Temperature — Celsius, Fahrenheit and Kelvin, with proper offset-scale conversion.
- Area — from square centimetre to the São Paulo alqueire, by way of hectare and acre.
- Volume — litres, millilitres and recipe measures (cup, tablespoon, teaspoon), plus gallon and fluid ounce.
- Speed — km/h, m/s, mph and knot.
- Time — from millisecond to year, in commercial values.
- Data storage — bits, bytes and both families of multiples, decimal and binary.
kB vs KiB: the difference that eats 10% of your drive
This is the case almost every conversion table on the internet gets wrong. There are two families of byte multiples, and they are not the same thing:
- Decimal (SI) — kB, MB, GB, TB, in powers of 1,000. This is what the drive manufacturer uses and what is printed on the box.
- Binary (IEC) — KiB, MiB, GiB, TiB, in powers of 1,024. This is what the operating system actually measures — Windows just displays it with the wrong label, while macOS and Ubuntu moved to decimal to match the box.
The gap grows with each multiple: 2.4% at kilo, 4.9% at mega, 7.4% at giga and 9.95% at tera. That is exactly why a 1 TB drive shows up as 931 GB in the file explorer — not a single byte is missing, the ruler changed. If what you need is the size of a text in bytes, the character counter computes UTF-8 right in the browser.
The Brazilian units nobody converts
Arroba (@) is 15 kg in Brazil and remains the trading unit for cattle and coffee — the arroba price for live cattle is published daily. Curiously it shares its symbol with email, and not by accident: the arroba was abbreviated as "@" in commercial ledgers centuries before the internet.
Alqueire is the land measure that changes by region: 24,200 m² in São Paulo (the default here), 48,400 m² in Minas Gerais and 27,225 m² in the North. Since the difference reaches 100%, confirming which alqueire is meant is a mandatory step in any rural land negotiation.
Precision and rounding
The factors used are the official ones, and exact where the definition is exact — inch (25.4 mm), pound (0.45359237 kg), nautical mile (1,852 m). Results are shown with up to 7 significant digits and switch to scientific notation when the order of magnitude leaves readable range. For time, month and year use the commercial values of 30 and 365 days; when the real calendar matters, the date calculator counts day by day, with holidays and leap years.
Works offline, in your browser
Every factor lives in the page code — no API call, no network request, and nothing you type leaves your machine. Once loaded, the page keeps converting even without an internet connection.
## faq
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54 cm — not a rounding, but the official definition: since the 1959 international yard and pound agreement, an inch is 25.4 millimetres by definition. Every other imperial equivalence follows from it: a foot is 12 inches (30.48 cm), a yard is 3 feet (91.44 cm) and a mile is 1,760 yards (1,609.344 m). A 50-inch TV measures 127 cm across the diagonal.
How do you convert Celsius to Fahrenheit?
Multiply by 1.8 and add 32: 25 °C × 1.8 + 32 = 77 °F. The way back is to subtract 32 and divide by 1.8. Temperature is the only conversion in this tool that is not a simple multiplication, because the scales have different zeros — 0 °C and 0 °F do not represent the same thing. That is why there is no single "factor": 20 °C is not double 10 °C on any other scale.
Why does my 1 TB drive show up as 931 GB?
Because the manufacturer and the operating system use different definitions of "giga". The manufacturer sells in decimal units: 1 TB = 1,000,000,000,000 bytes. Windows displays binary units but with the wrong label: what it calls "GB" is really GiB, of 1,073,741,824 bytes. Divide one by the other and you are left with 931 — no byte went missing, the ruler changed. That is exactly why this tool lists both families (kB/MB/GB and KiB/MiB/GiB) side by side.
What is an alqueire in square metres?
It depends on the region, and that is the trap. The São Paulo alqueire — the most widely used and the one adopted here — is 24,200 m², or 2.42 hectares. The Minas Gerais alqueire (also called geometric) is 48,400 m², double the size. There is also the Northern alqueire at 27,225 m². In land documents and negotiations, always confirm which measure is in use before running the numbers.
How many millilitres are in a recipe cup?
The standard Brazilian recipe cup holds 240 ml, which is the measure used in this tool. The value varies by country: the US legal cup is 240 ml, the older reference cup is 236.6 ml and the Japanese cup is 200 ml. Spoons are more stable: a tablespoon is 15 ml and a teaspoon 5 ml. In baking, where ratios are critical, weighing in grams gives far less error than measuring by volume.
How do you convert km/h to m/s?
Divide by 3.6. A speed of 108 km/h equals 30 m/s. The number 3.6 comes straight from the definition: 1 km/h is 1,000 metres divided by 3,600 seconds. The reverse is to multiply by 3.6 — the most useful shortcut when you read a speed in physics or in sensor data, always in m/s, and need to picture it on a speedometer.
How many days does a month have in this conversion?
Thirty, and a year has 365 — the commercial values used in deadlines and estimates. Real months run from 28 to 31 days and leap years have 366, so converting time by factor is good for orders of magnitude, not for exact dates. When the real calendar matters — a deadline in business days, an exact age, the difference between two dates — use the date calculator, which walks the calendar day by day.
Is the conversion done in my browser?
Yes. All the factors live in the page code and the calculation runs locally, with no network request. The tool works offline once loaded and no value you type is sent to or stored on any server.
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