Hex Converter

Hexadecimal is everywhere once you start looking: web colours, memory addresses, MAC addresses, error codes, character encodings. This converter moves numbers between hexadecimal and decimal in both directions, so a value like 0x2F3 stops being code and becomes 755 — and a plain figure like 1000 becomes the 3E8 you actually need to type into a style sheet, a debugger or a configuration file.

Quick Answer

Hex digits carry place values that are powers of sixteen, and the letters are numbers: A = 10, B = 11, C = 12, D = 13, E = 14, F = 15. To evaluate a hex number, multiply each digit by its power of sixteen and add: 0x2F3 = 2×256 + 15×16 + 3 = 755. To go the other way, divide the decimal number by 16 repeatedly and read the remainders backwards.

Sixteen Symbols, and Why Computers Like Them

Hexadecimal is base sixteen: after 9, instead of inventing new symbols, it recruits A through F. The reason for its existence is a tidy coincidence — four binary digits span exactly 0 to 15, one hex digit. So a byte, eight bits, is always exactly two hex digits, and any binary value can be rewritten in hex by grouping bits in fours, with no arithmetic at all. Hex is binary made legible: a quarter of the length, none of the information lost.

That is why hex became the spelling of low-level computing. A memory address like 0x7FFF is readable at a glance and hopeless in binary. Web colours are three bytes in a row — red, green and blue — so #FF5733 simply means red at FF (255), green at 57 (87) and blue at 33 (51). Character encoding uses hex because every character is a byte: the letter A lives at 0x41 (65) in ASCII and UTF-8. Even the 0x prefix itself is a signal, a convention from the C programming language meaning "what follows is hexadecimal," so 10 and 0x10 are different numbers — ten and sixteen.

Reading hex fluently means recognising landmarks. 0x10 is 16, 0x100 is 256, 0x1000 is 4096; 0xFF is 255, the largest byte. Doubling a hex number is not like doubling a decimal one — 0x20 is 32, and its double is 0x40, because the place values, not the digits, doubled. The converter handles the arithmetic; these anchors are what let you judge whether its answer makes sense.

How to Use the Hex Converter

1. Enter your hexadecimal value with or without the 0x prefix — the digits 0–9 and letters A–F are what matter, and case makes no difference.
2. Read the decimal equivalent when you need the number's ordinary size — for comparing addresses, checking a byte value or following documentation written in decimal.
3. To convert the other way, enter the decimal number and read off the hex form.
4. For colour work, convert each channel separately: a decimal red, green and blue each become a two-digit hex pair, concatenated with a # in front.
5. Check suspicious results with a landmark: a three-digit hex number must land between 256 (0x100) and 4095 (0xFFF) in decimal.
6. Keep leading zeros when the value is a fixed-width field — 0x0A and 0xA are equal as numbers but not as bytes.

Worked Example: Reading 0x2F3 and Writing 1000 in Hex

Decode 0x2F3 by place value. The three digits sit over 16² = 256, 16¹ = 16 and 16⁰ = 1. So 2×256 = 512, F is 15 and 15×16 = 240, and 3×1 = 3. Adding: 512 + 240 + 3 = 755. Now encode 1000 by repeated division: 1000 ÷ 16 = 62 remainder 8; 62 ÷ 16 = 3 remainder 14, which is E; 3 ÷ 16 = 0 remainder 3. Reading the remainders from last to first gives 0x3E8, and the check is quick: 3×256 + 14×16 + 8 = 768 + 224 + 8 = 1000.

The colour example rewards the same skill. A designer given the decimal triple (255, 87, 51) converts each channel: 255 = FF, 87 = 5×16 + 7 = 57, and 51 = 3×16 + 3 = 33. Joined together, the hex colour is #FF5733 — a warm orange-red that a browser can use directly.

Hex Habits That Cause Bugs

Typing hex digits into a decimal field (or the reverse) is the most expensive habit: the string "100" means one hundred in decimal and 256 in hex, and software rarely warns you which one it assumed. Second, letters beyond F — G, H and beyond — are not hex digits at all; if a value contains them, it belongs to some other notation or it is simply wrong. Third, remember that hex fractions and negative values in real systems follow encoding conventions (two's complement, floating point) rather than schoolbook rules, so a raw conversion describes the pattern, not necessarily the signed value.

Case, at least, is a non-issue: 0xff and 0xFF are the same number in every standard, though many style guides pick one and stay consistent. And when copying values from a memory dump, respect the grouping — bytes are often printed in pairs precisely because each pair is one byte, and regrouping them differently changes the number entirely.

A modern extension of the colour example shows hex doing quieter work. CSS colours accept an eight-digit form, #RRGGBBAA, where the final pair is an alpha channel controlling opacity on the same 0–255 scale. The colour #FF5733 at half strength is therefore written #FF573380, because 0x80 is 128 — almost exactly half of 255. Designers read such values constantly, and recognising that 80 is "half" in byte terms, just as FF is "full" and 00 is "none", turns strings that look like serial numbers into readable instructions. Any pair you meet divides by 16 for its first digit and takes the remainder as its second, which is the whole conversion in miniature.

Companion Number Tools

Bits are the layer beneath hex: the Binary Converter shows any of these values as raw ones and zeros, and the Decimal Converter produces binary, hex and octal from a decimal starting point in a single pass. You will find every other conversion family — units, temperature, text encodings — in the converters section.