How to Read Binary Code: A Beginner's Guide

Updated October 8, 2026 · 7 min read · By the Hacker Typer team

Binary looks unreadable, but it follows one simple rule. Once you know it, you can turn 01001000 01101001 into "Hi" with nothing but addition. This guide takes you from zero to reading binary text by hand.

What binary is

The numbers we use every day are base 10. There are ten digits, 0 to 9, and each position is worth ten times the one to its right: ones, tens, hundreds.

Binary is base 2. There are only two digits, 0 and 1, and each position is worth twice the one to its right: ones, twos, fours, eights. Computers use it because a circuit has two easy states, off and on.

One binary digit is a bit. Eight bits make a byte, and text is normally written one byte per character.

Step 1: learn the place values

For an eight-bit byte the positions are worth, from left to right:

Each value is double the next. This row of eight numbers is the only thing you need to memorise.

Step 2: add up the positions that hold a 1

Write the byte under the place values. Wherever there is a 1, keep that value. Wherever there is a 0, ignore it. Add what is left.

Example: 01000001

There is a 1 under 64 and a 1 under 1. 64 + 1 = 65.

Another: 00101101 has ones under 32, 8, 4 and 1. 32 + 8 + 4 + 1 = 45.

Step 3: turn the number into a letter

Text uses a lookup table called ASCII that gives every character a number. You do not need the whole table. Three anchors cover the alphabet:

• Capital A is 65, B is 66, and so on up to Z at 90.
• Lower-case a is 97, b is 98, up to z at 122.
• A space is 32. The digits 0 to 9 are 48 to 57.

So the byte from step 2, 65, is the letter A.

The shortcut for reading letters fast

ASCII was designed with a pattern that makes letters easy to spot without adding up the whole byte. Split each byte into its first three bits and its last five.

• First three bits 010 mean a capital letter.
• First three bits 011 mean a lower-case letter.
• The last five bits give the letter's position in the alphabet: 00001 is the 1st letter, 00010 the 2nd, 00011 the 3rd.

For the last five bits the place values are just 16, 8, 4, 2, 1. Take 011 01000: lower-case, and 01000 is 8, so it is the 8th letter, h.

Two more patterns are worth knowing. A byte starting 0011 is a digit, and its last four bits are the digit itself, so 0011 0111 is 7. And 00100000 is a space.

A full worked example

Decode 01001000 01100101 01101100 01101100 01101111.

The message is Hello.

Writing a number in binary

To go the other way, work through the place values from the left. If the value fits into what remains of your number, write 1 and subtract it. If not, write 0.

Example: 77. Does 128 fit? No, 0. Does 64 fit? Yes, 1, leaving 13. 32? No. 16? No. 8? Yes, leaving 5. 4? Yes, leaving 1. 2? No. 1? Yes. Result: 01001101, which is the letter M.

Practice

Try these before looking at the answers.

1. 01001111 01001011
2. 01100011 01101111 01100100 01100101
3. 00110100 00110010

Answers: 1 is "OK". 2 is "code". 3 is "42".