Frequently asked questions
Short answers about how Convertly works.
How do I convert a value?
Open a converter, type the number in the input box, and choose the units to convert from and to. The result updates as you type. Use the swap button to reverse the units.
How accurate are the results?
Conversions use the exact published definitions where they exist, and calculations are done at full precision in your browser. Results are rounded only when displayed, normally to 8 significant digits. Always check critical calculations against an authoritative source.
Why do some sources give slightly different values?
Some units have more than one definition. Convertly uses the thermochemical calorie (4.184 J), the International Table BTU, the mechanical horsepower, the US gallon on US pages and the imperial gallon on imperial pages. Decimal data units such as the kilobyte (1,000 bytes) differ from binary units such as the kibibyte (1,024 bytes).
Why do I get an error when I enter a negative number?
Some quantities cannot be negative, so mass, area, volume, time and digital storage show an error for negative input. Quantities that can be negative, such as temperature and length, accept negative values. Temperatures below absolute zero are rejected.
Does Convertly store the numbers I type?
No. Conversions run entirely in your browser and the values you enter are not sent to our server. Read the Privacy Policy for details about server logs and advertising.
What does the precision control do?
A few converters let you choose how many digits to show. It only changes how the result is displayed, not how it is calculated. It appears only where it is useful, so most pages do not have it.
How do I find a converter quickly?
Use the search box on the home page or on the All units pages. Type something like inches to cm and choose a result. You can also browse by category from the Categories menu.
How do I report a mistake or suggest a converter?
Email sohaildomainseo@outlook.com with the page address and a short description. We review corrections and suggestions as we can.