Developer Unit Converter — Bits, Bytes, Number Bases, and Time Units in One Place

Unit Conversion for Developers

When coding, you repeatedly need to convert between units. Is this file size in bytes or kilobytes? How many minutes is that API response time in milliseconds? How do you convert hexadecimal to decimal? This tool handles those calculations quickly.

개발자 & 디자이너 유틸리티

PX to REM Converter

Pixel (px)

Base (px)

1.000rem

Color Converter (HEX to RGB)

HEX Color

rgb(59, 130, 246)

* 이 도구는 ahoxy-nextjs의 유틸리티 라이브러리를 기반으로 blog-oiyo용으로 최적화되었습니다.

---

Data Size Units

The basic unit of computer data is the bit, and 8 bits make one byte.

Unit	Size	Abbreviation
Bit	0 or 1	bit
Byte	8 bits	B
Kilobyte	1,024 B	KB
Megabyte	1,024 KB	MB
Gigabyte	1,024 MB	GB
Terabyte	1,024 GB	TB
Petabyte	1,024 TB	PB

Note: Hard disk manufacturers label drives using 1 KB = 1,000 B (decimal), but operating systems calculate 1 KB = 1,024 B (binary). This difference is why a “500 GB hard drive” actually shows up as about 465 GiB in your OS.

---

Number Base Conversion

Decimal → Binary

Repeatedly divide by 2 and read the remainders in reverse order.

10 ÷ 2 = 5 remainder 0
 5 ÷ 2 = 2 remainder 1
 2 ÷ 2 = 1 remainder 0
 1 ÷ 2 = 0 remainder 1
Result: 1010₂ (read remainders in reverse)

Hexadecimal (Hex)

Hexadecimal uses digits 0–9 and letters A–F. It appears frequently in color codes (#FF5733), memory addresses, and SHA hashes.

Decimal	Hex
10	A
11	B
12	C
13	D
14	E
15	F
16	10
255	FF

CSS color example: #FF5733 = R:255, G:87, B:51

Quick Base Conversion (JavaScript/Python)

// JavaScript
(255).toString(2)   // → "11111111" (binary)
(255).toString(16)  // → "ff" (hexadecimal)
parseInt("ff", 16)  // → 255 (hex → decimal)

# Python
bin(255)   # → '0b11111111'
hex(255)   # → '0xff'
int('ff', 16)  # → 255

---

Time Unit Conversion

These come up constantly with API response times, cache TTLs, and timer configurations.

Unit	Conversion
1 second	1,000 milliseconds (ms)
1 minute	60 seconds = 60,000 ms
1 hour	3,600 seconds = 3,600,000 ms
1 day	86,400 seconds
1 week	604,800 seconds

Pro tip: JWT expiration times, Redis TTLs, and setTimeout values all use milliseconds or seconds. Since it is easy to mix them up, define them as named constants:

const ONE_HOUR_MS = 60 * 60 * 1000;
const ONE_DAY_SECONDS = 24 * 60 * 60;

---

Network Speed Units

Unit	Description
bps	bits per second
Kbps	1,000 bps
Mbps	1,000,000 bps
Gbps	1,000,000,000 bps

Note: Internet speeds are measured in bits (lowercase b), while file sizes use Bytes (uppercase B).

• Download time for a 100 MB file over a 100 Mbps connection: 100 MB × 8 = 800 Mb ÷ 100 Mbps = 8 seconds