The converter that does not round behind your back
Every factor is stored as an exact fraction and the rounding happens once, when the number reaches the screen. That is why a tebibyte here is 1 099 511 627 776 bytes and not 1 099 511 628 000.
- Exact fractions, not floating point
- Free-text input
- Batch mode
- Nothing is uploaded
Hold Alt to replace every rounded figure with its exact value.
Every unit at once
1 mA whole column at once
Paste a column of values — or open a text file — and convert every line in one go. Nothing is read until you press the button.
With that box ticked the tool reads only the digits and applies the input unit you picked, so nothing is guessed from the text.
How it works
Pick the family
Eighteen of them, from length and mass to pressure, data rate and fuel economy. Or press Ctrl+K and search all 156 units at once.
Type the quantity
A plain number, a fraction like 3/4, a mixed number like 1 1/2, a percentage, or a compound value such as 5'11" or 2 ft 3 in.
Tune the output
Choose significant digits or fixed decimals, switch to scientific or engineering notation, add thousands separators, or break the result into feet and inches.
Take it further
Copy a single figure, download the whole table as CSV, or send it straight to another oLoveTools tool without a trip through your downloads folder.
Exact fractions, not floats
Every factor is a ratio of big integers — a foot is 3048/10000 of a metre, not 0.3048 — so the arithmetic carries no error and the rounding happens once, on screen.
Compound results
1.8542 m as 6 ft 1 in, 5445.5 s as 1 h 30 min 45.5 s, 41.4025° as 41° 24' 9". The whole part is exact and only the last piece carries decimals.
Convert a column
Paste or open a list and convert every line in one pass, with the unreadable lines flagged instead of silently dropped.
156 units, one search box
Ctrl+K searches names, symbols and aliases across all eighteen families, and jumps to the right one. Pin the units you use to keep them on top.
Precision you control
Significant digits, fixed decimals, scientific and engineering notation, and thousands separators that follow your language.
Keyboard first
Ctrl+K to search, S to swap, Ctrl+Z and Ctrl+Shift+Z to move through your history, and Alt held down to reveal the exact value behind every rounded one.
Chained to the rest
Send the results to the list cleaner, the JSON viewer, the Markdown preview or the diff tool, and receive files from them the same way.
Nothing leaves the tab
No upload, no API call, no account. Every figure is computed by your own browser, and closing the tab discards all of it.
Frequently asked questions
Why do other converters give a slightly different answer?+
Because most of them multiply by a floating-point factor and then round the result to a fixed number of significant digits. That is fine for a kitchen measurement and wrong for a storage figure: rounding 1 099 511 627 776 bytes to ten digits returns 1 099 511 628 000, which is not the same number with less detail — it is a different number. Here the value stays a fraction of big integers until it is printed, and the precision you choose never eats into the integer part.
What can I type into the input box?+
A plain number with either a dot or a comma as the decimal mark, a fraction like 3/4, a mixed number like 1 1/2, a percentage like 12%, scientific notation like 1.25e-4, a value with its unit written out like 12 km or 90 km/h, a compound value like 2 ft 3 in or 1h 30min, and feet-and-inches notation like 5'11". If a unit is written in the text it wins over the selector; if not, the selector is used.
What does the ≈ mark next to some units mean?+
That the definition itself is not exact, so no converter can be. Radians depend on π, which is irrational; the average month and the average year are calendar averages; Mach depends on the temperature of the air. Everything else in the catalogue is defined exactly by treaty or by standard, and the arithmetic here preserves that exactness.
How do I see the value without any rounding?+
Hold down Alt. Every figure on screen switches to its exact form: the full decimal expansion when the fraction has one, and the irreducible fraction itself when it does not — one third of an inch is shown as a ratio rather than as 0.333… truncated somewhere.
Can I convert a whole list at once?+
Yes. Paste a column into the batch box, or open a .txt or .csv file, and press the convert button. Lines that cannot be read are marked rather than dropped, so the output lines up with the input. Ticking the manual box makes the tool ignore any unit written in the lines and apply the one you selected instead.
Does anything I type get uploaded?+
No. There is no server component and no network request at any point in a conversion. Files you open are read locally by the browser and never sent anywhere. The current conversion is written into the page URL so you can share or bookmark it — that is the only place your numbers are stored, and it stays on your machine unless you send the link yourself.