All Tools VerseAdding hex numbers follows the same column method as decimal, but you carry whenever a column reaches 16 instead of 10, and the digits run 0 to 9 then A to F. Add hex 8 and hex 9 and you get 11 in hex, because 8 plus 9 is 17, which is one 16 with 1 left over. This guide shows how to add hexadecimal numbers by hand, how bitwise hex differs, and free tools for both.
In this guide
Hex digits and carrying
Hexadecimal has 16 digits: 0 to 9, then A, B, C, D, E, F for the values ten through fifteen. Addition works column by column from the right, and you carry a 1 whenever a column total reaches 16. The only extra step versus decimal is translating between letters and values, so A is 10 and F is 15. Our number systems guide covers why hex uses base 16.
Add hex step by step
Add hex 2B and 19. Rightmost column: B is 11, plus 9 is 20. Twenty is one 16 with 4 left over, so write 4 and carry 1. Next column: 2 plus 1 plus the carried 1 is 4. The result is 44 in hex. If a column total lands between 10 and 15, you write the matching letter rather than carrying. The hex addition calculator shows the carries and the digit translation as it works.
Bitwise hex is different
Adding is not the same as a bitwise operation. A bitwise AND, OR, or XOR compares the bits of two hex values position by position with no carrying at all, which is how masks and flags are combined. Hex F AND hex 6 is 6, not a sum. The bitwise hex AND tool handles that, and the concepts behind each operator are in our bitwise operations guide.
Check your answer
Convert both hex inputs and the result to decimal and confirm the sum. For 2B and 19, that is 43 plus 25, which is 68, and hex 44 is 68. The hex to decimal converter makes the check instant and catches any carry you missed.
Where hex math is used
Hex arithmetic comes up in low-level work: calculating a memory address by adding an offset to a base, stepping through a byte range, or working out a checksum. Because hardware values are shown in hex, doing the math in hex avoids constant conversion to decimal and back. Knowing when you need a sum versus a bitwise operation is the key distinction, since they answer different questions about the same two values.
Free tools used in this guide
Frequently asked questions
How do I add hex numbers?
Add column by column from the right and carry a 1 whenever a column total reaches 16, translating letters to values so A is 10 and F is 15.
What is hex 8 plus hex 9?
It is 11 in hex, because 8 plus 9 is 17, which is one 16 with 1 left over.
Is adding hex the same as a bitwise OR?
No. Addition carries between columns, while a bitwise OR compares bits position by position with no carry, so they give different results.
How do I check a hex addition?
Convert both inputs and the result to decimal and confirm the sum matches. A hex to decimal converter does this quickly.
Why do programmers add in hex instead of decimal?
Because addresses and byte values are shown in hex, so adding in hex avoids converting to decimal and back for every calculation.