Example 1
- test
mod 256: 192, mod 65536: 448
What checksum for test? mod 256: 192, mod 65536: 448. A byte sum, not SHA.
Checksum calculator
Type text. test gives mod 256: 192, mod 65536: 448. hello gives 20 and 532. CalcBoxer gives 147 and 915. A byte sum, not a hash.
This is a demo UTF-8 byte sum modulo 256 and 65536, not CRC-32, not MD5, and not SHA. Another number base sits on binary / hex / decimal.
Results
Enter data and click Calculate.
How it works
Checksum in this calculator is a UTF-8 byte sum. test gives mod 256: 192, mod 65536: 448. hello gives mod 256: 20, mod 65536: 532. CalcBoxer gives mod 256: 147, mod 65536: 915. The calculator does not compute CRC-32, MD5, or SHA.
Each character becomes UTF-8 bytes, those bytes add up, then the remainder after 256 and after 65536. test totals 448, so 448 - 256 = 192 on the short modulus. This is not a signature and not a cryptographic digest.
Letter case changes the sum. Test and test are two entries. A space adds a byte too. Blank text does not give a mod pair. The calculator does not read a file from disk, only the cs-str field.
Binary / hex / decimal next door converts one number between bases. Here the character sum stays. 192 for test is not a hex code. 448 is not CRC.
Type test, then Calculate. The result is mod 256: 192, mod 65536: 448. hello gives 20 and 532. CalcBoxer gives 147 and 915.
test gives mod 256: 192, mod 65536: 448. hello gives 20 and 532. CalcBoxer gives 147 and 915. A different string gives a different sum.
Formula
UTF-8 byte sum; result = sum mod 256 and sum mod 65536
How to use
- Type the text test in the field.
- Click Calculate. The result is mod 256: 192, mod 65536: 448.
- hello gives 20 and 532. CalcBoxer gives 147 and 915.
- This is a UTF-8 byte sum, not CRC and not SHA.
- The next card converts one number between bin / hex / dec.
test gives mod 256: 192, mod 65536: 448
UTF-8 byte sum, then mod 256 and mod 65536. test gives 192 and 448. This is not SHA.
- Checksum
- Added UTF-8 bytes. test totals 448, so 192 on mod 256.
- mod
- Remainder after 256 and 65536. hello gives 20 and 532. Not CRC.
- bytes
- UTF-8 from the text field. CalcBoxer gives 147 and 915. Not MD5.
Examples
Example 2
- hello
mod 256: 20, mod 65536: 532
What checksum for hello? mod 256: 20, mod 65536: 532.
Example 3
- CalcBoxer
mod 256: 147, mod 65536: 915
What checksum for CalcBoxer? mod 256: 147, mod 65536: 915.
Related calculators
Common questions
What checksum for test?
mod 256: 192, mod 65536: 448. A UTF-8 byte sum, not SHA.
What about hello?
mod 256: 20, mod 65536: 532.
What about CalcBoxer?
mod 256: 147, mod 65536: 915.
Is this CRC-32 or MD5?
No. The calculator adds bytes and takes the remainder of 256 and 65536.
Is this SHA?
No. This is a demo. SHA is outside this calculator.
Does letter case matter?
Yes. Test and test give a different sum, because the UTF-8 bytes differ.
Does a space enter the sum?
Yes. Every character in the field, including a space, adds its bytes.
How is this different from a character code?
That card is one character. Here the whole string test gives 192 and 448.
Is 192 a file hash?
No. It is the remainder of the byte sum of the text you typed.
Knowledge sources
The calculator counts bits, bytes or throughput from your numbers. Below are SI and bit definitions (NIST).
Page updated in 2026.