Hex Subtraction Calculator

How it is calculated

Both entries are read as hexadecimal numbers (digits 0 to 9 and letters A to F, upper or lower case) and converted to ordinary numbers: A = Σ digit × 16position, and the same for B. The tool then computes A − B and shows it both as hex and as a decimal number, together with the two decimal values it started from. By hand you work column by column from the right, and when a digit is too small you borrow 1 from the next column, which adds 16 (not 10) to the current one. Enter plain digits only, with no 0x prefix or spaces. Leading zeros are ignored. The first number must be at least as large as the second: a negative difference gives no result. After leading zeros, each value may have at most 13 hex digits (below 2⁵²), so the decimal digits are always exact; longer values give no result instead of a rounded answer.

Common mistakes

• Typing a prefix such as 0x or # before the number: the tool accepts only the digits 0 to 9 and letters A to F, so these give no result.
• Putting the numbers in the wrong order: the first box is the number you subtract from, and a smaller first number gives no result rather than a negative answer.
• Borrowing 10 instead of 16 when subtracting by hand, which is the usual cause of a wrong answer when checking the tool.
• Treating a hex string like 10 as ten: it is sixteen, so 10 − 1 is F (15), not 9.
• Pasting a 64-bit address of 16 hex digits: values longer than 13 significant hex digits are refused, so split the address or subtract the low part by hand.