ConvertAll FAQ

A1: A free conversion calculator with over 370 units in 33 categories, from length, weight and volume to pressure, energy, electricity and radiation, and 14 practical tools: cooking, a recipe scaler, oven temperatures, clothing, shoe and ring sizes, trip fuel cost, tyre sizes, time zones, number bases, paper and photo sizes, wire gauges, BMI and lakh and crore. Everything is on one page, under four tabs: Convert, Browse (on phones and tablets), Saved and Settings.

A2: It is free and there is no account or registration. Like every page on ZeroDataUpload, it is supported by advertising.

A3: No. Every conversion is worked out by your browser on your device. The page itself, its ads and its analytics load from the internet as on any website, but what you type is never sent with them, and the address in your browser is not changed while you type.

A4: Your saved pairs (up to 100), your recent conversions (up to 100), the units you last used in each category, pinned units, the values you typed in the tools, your time zone cities and your settings, so they are still there next time. Nothing is kept until you change something: opening the page or moving between categories and tools writes nothing. Reset everything in Settings removes it all.

A5: UnitSwap, the site's earlier unit converter, became part of ConvertAll on 15 November 2026, so the site has one unit converter instead of two, and UnitSwap's old address opens this page. Its units are all here: 24 were added for that, among them three old temperature scales, the rood, the barn and boiler horsepower. Only Mach, the jiffy and the computer word sizes were left out, because they have no single fixed size. ConvertAll covers 33 categories with over 370 units, reads conversions typed in words, shows a two-scale tape and adds kitchen, size, travel, Indian and science tools. A few of its tools are also tools of their own on this site: BaseShift converts number bases, the Time Zone Converter compares cities, AutoCalc compares tyre sizes and trip costs in more detail, HomeCalc measures property areas with land units, EngCalc sizes cables, and Passport Photo Maker makes passport photos. Use whichever fits the job.

A6: Current versions of Chrome, Edge, Firefox and Safari on computers and phones. From 1024 pixels wide the list of categories and tools sits beside the converter; on narrower screens it is under the Browse tab.

A7: Type it the way you would say it in the search bar: "5 ft 11 in to cm", "72 f to c", "65 mph in km/h", "3 bigha in acres" or "500 GB to GiB", then press Enter or pick a match. Without a target, such as "30 psi", ConvertAll suggests the usual ones. You can also type a category, unit or tool name, such as "pressure" or "oven", to open it.

A8: Plain numbers, fractions (3/4, 1 1/2, 1½), powers (2.5e3 or 2.5 x 10^3), sums with brackets ((12 + 8) * 3) and values with units of the same kind (5 ft 11 in, 2 m + 30 cm, 5' 11"). A bare number after feet, stone, pounds, hours, minutes or degrees is the next smaller unit, so 5'11, 10 st 4 and 1 h 30 work too, and a bracket straight after a value multiplies: 2(3 + 4) is 14. A note under the box shows how your text was read. Each box takes up to 200 characters.

A9: Exact means the answer shown is complete to its last digit, because the two units are related by a short decimal (a mile is exactly 1.609344 km). Rounded means more digits exist; raise the precision in Settings to see them. Approximate means one of the units has no single fixed size, such as a regional land measure like the bigha, a traditional unit such as the ratti, or an em, whose size depends on the text.

A10: In Settings choose 1,234,567.89, the Indian 12,34,567.89, 1.234.567,89, 1 234 567,89 or 1234567.89. The format also sets how typed numbers are read, so 1,5 means one and a half only with a comma format. Precision gives automatic (up to 12 significant digits, with long whole numbers written in full) or a fixed number of decimal places; it shapes the answers and never changes what you typed, and very large or small numbers can be written in scientific or engineering notation.

A11: The yellow tape shows your value on both scales at once, the From unit on top and the To unit below, with the red needle at your value. Drag it sideways, or focus it and use the arrow keys (Page Up and Page Down take bigger steps, Home goes to zero), to change the value. The plus and minus buttons zoom the scale.

A12: Yes. Under the tape, Every length unit (or weight, volume and so on) lists the value in each unit of the category. Filter the list, click a unit to make it the To unit, copy any value, or pin the units you use most to the top.

A13: Save pair keeps the two units in the quick pairs row and under Saved; recent conversions appear there too, newest first. Link copies a link to the conversion on screen; the person who opens it sees the same units and value. The link is read when the page opens and then taken out of the address.

A14: From the published definitions: NIST Special Publication 811 and NIST Handbook 44 for US and imperial units, the SI Brochure for metric units, CODATA 2022 for the dalton, the elementary charge and the faraday, the CSS standard for screen units, NIST's binary prefixes for KiB and MiB, and the Standards of Weights and Measures Act, 1976 for the tola, seer and maund. The 24 units brought over from UnitSwap in November 2026 follow NIST Special Publication 811 where it lists them (the barn, the shake, boiler horsepower, the slug per cubic foot), and otherwise the dictionary of units kept at the University of North Carolina (square rod, rood, quadrant, sign) and the two fixed points of the Delisle and Rømer scales.

A15: They are now based on the international foot (exactly 0.3048 m). NIST retired the US survey foot at the end of 2022, and Handbook 44 gives these units in international feet; older tables used the survey foot, which is two parts in a million longer.

A16: A US gallon is 231 cubic inches, 3.785411784 litres; a UK (imperial) gallon is 4.54609 litres, about 20% more. The same goes for their pints, quarts and fluid ounces, which ConvertAll keeps apart, and for miles per gallon in fuel economy.

A17: A tola is 11.6638038 grams (180 grains), a seer 80 tola or 0.933104304 kg and a maund 40 seer or 37.32417216 kg, as the Standards of Weights and Measures Act, 1976 gives them. A masha is a twelfth of a tola. The ratti and the seer and maund are marked approximate, because local sizes differed.

A18: Traditional Indian land measures differ from state to state and even between districts: a bigha can be 14,400, 17,424 or 27,225 square feet, among others. Each unit is named with the size it uses (for example "Bigha, 27,225 sq ft"), so you can pick the one your area uses. Check the size in your own land records, or ask the local revenue office, before you rely on it. The cent (a hundredth of an acre), the guntha (a fortieth) and the murabba (25 acres) are fixed by their names.

A19: Drive makers use decimal units (1 GB is 1,000,000,000 bytes), while many computers count in binary units (1 GiB is 1,073,741,824 bytes). ConvertAll lists both, so 1 TB is 931.32 GiB. Data speeds are usually in bits: 100 Mbit/s is 12.5 MB/s.

A20: Only units with a published size are kept. Mach depends on the temperature of the air, and no standard table could be checked, so it is left out, as are the cubit, the nox, the rutherford and a "UK cup", which had no clear source. From UnitSwap, the site's earlier unit converter, the jiffy was not brought over (it stands for several different lengths of time), nor the computer word, double word and quad word (their size depends on the kind of computer). The Newton temperature scale is here but marked Approximate: it was never fixed by a second point, so the usual 33 for boiling water is used.

A21: From the U.S. Department of Agriculture's FoodData Central (its SR Legacy data), which gives the weight of one US cup of each food, and of a teaspoon for baking powder, baking soda and yeast. For anything else choose Other and type the grams in one cup from the packet or your own scale. How you fill a cup changes the weight, so a kitchen scale is the sure way.

A22: Paste a recipe and choose a factor, such as 2 or 1/2, or the servings it makes and the servings you need. Every amount is scaled and rounded to kitchen fractions such as ½ and ⅓. With "only the amount at the start of each line" (on by default), oven temperatures, pan sizes and times further along a line stay as they are. Amounts written with a decimal comma (1,5 l) or a thousands mark (1,000 g) are read as well. A recipe can be up to 20,000 characters.

A23: From the oven chart of Which?, the UK consumer body: gas mark 1 is 140 °C (275 °F) up to gas mark 9 at 240 °C (475 °F), and a fan oven is set 20 °C lower. Ovens vary, so an oven thermometer shows what yours really does.

A24: No: they are example charts, because there is no single standard between countries and every brand sizes a little differently. Type your measurement to see the closest row (a measurement outside a chart is said to be outside it, and no size is named), then check the brand's or jeweller's own chart. In the ring chart, EU sizes are the inside circumference in millimetres.

A25: From the distance (doubled for a return trip), your car's fuel economy and the fuel price you type, split between the people sharing. The carbon dioxide counts only the fuel burnt, from the US Environmental Protection Agency's figures: 8,887 g for a US gallon of petrol and 10,180 g for a gallon of diesel (2.35 and 2.69 kg a litre). There is no fuel price built in: prices change, so you type yours.

A26: It reads a size such as 205/55R16 (width in mm, sidewall as a percentage of the width, rim in inches) and works out the sidewall, overall diameter, circumference and revolutions per kilometre. With a second size it shows the difference and what your speed really is when the speedometer shows a value. A size within about 3% of the original diameter is the usual guide; check the car's handbook or ask a tyre dealer.

A27: It uses your browser's time zone data, which follows each country's rules, including daylight saving. Pick a base city and a moment, or keep Now, and add the cities you need; they are kept for next time.

A28: Whole numbers of up to 1,000 digits, in binary, octal, decimal, hexadecimal or any base from 2 to 36; 0x, 0b and 0o prefixes work. It shows the number in every base and its size in bits and bytes.

A29: A and B sizes follow ISO 216 and C sizes and the DL envelope ISO 269; US Letter, Legal and Tabloid are whole inches. The tool shows them in millimetres, centimetres, inches or points, with the pixels needed at a print resolution, and draws the chosen size beside A4.

A30: No: it gives sizes only. Diameters come from the American Wire Gauge's definition (No. 0000 is 0.46 inch and No. 36 is 0.005 inch, with 38 sizes in equal steps between, as NBS Handbook 100 sets out), and the resistance is for annealed copper at 20 °C. Choose a cable for a circuit by your local electrical code and the cable maker's ratings.

A31: Two standards, your choice. The WHO's: below 18.5 underweight, 18.5 to 24.9 normal, 25 to 29.9 overweight and 30 and over obesity. For India, the India Obesity Commission's revised definition of 2025: normal 18.5 to 22.9, then BMI grades from 23, which it counts as generalised obesity whose stage a doctor decides. BMI is for adults and is a screening number, not a diagnosis; talk to a doctor about your own health.

A32: Yes. The lakh and crore tool writes any amount of up to 21 digits in the Indian system (crore, lakh, thousand) and the international one (million, billion), as "Rupees ... Only" with paise if you like. You can type 2.5 crore, 3 million or 12,34,567.