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Digital storage is measured in a ladder of units — bits, bytes, and kilo/mega/giga/tera multiples — and knowing how many megabytes are in a gigabyte, or how a file size compares to a drive's capacity, comes up constantly. This converter moves between every unit instantly.
Enter a value, pick the units, and the converted size appears at once.
How is it calculated?
The units
- Bit: the smallest unit — a single 0 or 1. 8 bits = 1 byte.
- Byte: one character of text. The base unit for file sizes.
- KB, MB, GB, TB, PB: each step up is 1,024× the previous, in the binary system this tool uses.
| Unit | Bytes |
|---|---|
| 1 KB | 1,024 |
| 1 MB | 1,048,576 (1,024²) |
| 1 GB | 1,073,741,824 (1,024³) |
| 1 TB | 1,024 GB |
Binary (1024) vs decimal (1000)
There are two conventions, and they cause real confusion: - Binary (1024-based): what operating systems report — 1 GB = 1,024 MB. This tool uses binary. - Decimal (1000-based): what drive manufacturers use — 1 GB = 1,000 MB. It's why a "1 TB" drive shows as ~931 GB in your OS.
The technically correct binary names are KiB, MiB, GiB, but everyday usage still says KB, MB, GB — which is the convention here.
Bits vs bytes
Watch the case: b is bits, B is bytes. Internet speeds are quoted in megabits per second (Mbps), while file sizes are in megabytes (MB). Since 1 byte = 8 bits, a 100 Mbps connection downloads at about 12.5 MB/s.
Where it helps
- Comparing a file size to a drive or upload limit
- Understanding why a drive shows less capacity than advertised
- Converting a download speed (bits) to a transfer rate (bytes)
Worked example
How many megabytes is a 1 GB file? In the binary system, 1 GB = 1,024 MB. So a 4 GB video is 4,096 MB. This is also why a drive sold as "1 TB" (1,000,000,000,000 bytes, decimal) shows as only about 931 GB in your operating system, which counts in 1,024s — the same bytes, two different unit conventions. And on the bits-vs-bytes point: 8 bits make 1 byte, so a 100 megabit-per-second (Mbps) internet plan transfers files at roughly 100 ÷ 8 = 12.5 megabytes per second.
FAQ
How many MB are in a GB?+
1,024 MB in the binary system operating systems use (1 GB = 1,024³ bytes). In the decimal system drive makers use, 1 GB = 1,000 MB. This tool uses the binary 1,024-based convention.
Why does my 1 TB drive show as 931 GB?+
The drive is 1 TB in decimal (1,000,000,000,000 bytes), but your OS counts in binary (1,024s), so it shows ~931 GB. Same bytes, different unit convention — no storage is missing.
What is the difference between bits and bytes?+
8 bits make 1 byte. Bits (lowercase b) measure data speed (Mbps); bytes (uppercase B) measure file size (MB). A 100 Mbps connection is about 12.5 MB/s.
What is binary vs decimal storage?+
Binary counts in 1,024s (1 GB = 1,024 MB) — used by operating systems. Decimal counts in 1,000s — used by drive manufacturers. The strictly correct binary names are KiB, MiB, GiB.
How do I convert internet speed to download time?+
Convert the speed from bits to bytes (÷ 8), then divide the file size by that. A 1 GB file on a 100 Mbps (12.5 MB/s) line takes about 1,024 ÷ 12.5 ≈ 82 seconds.
How big is a petabyte?+
1 PB = 1,024 TB = over a million GB. Petabytes are used for very large datasets and data-centre storage — far beyond everyday file sizes.