How Many MB Are in a GB? (1024 or 1000)

This page answers the single most-asked storage question — how many megabytes are in a gigabyte — and shows the conversion for any number you enter.

Quick answer: 1 GB = 1,024 MB under the binary rule that Windows and most software use, and 1 GB = 1,000 MB under the decimal rule that carriers, drive makers and cloud providers use. Both are correct; the 2.4% gap per step is why a “64 GB” card shows 59.6 GiB.

Which convention should the plain KB/MB/GB/TB labels use?

Value

From

Result

1,024

1 GB = 1,024 MB

Exact factors

1 GB =1,024 MB

1 MB =0.000976563 MB

Bytes per unit1,073,741,824 B = GB

Same value, other convention

With the 1000 rule1,000 MB

The two lines are the same file — only the definition of “GB” differs. This 2.4% gap per step is why a 1 TB drive shows 931 GiB in Windows.

Common GB → MB values

GB	MB
1	1,024
2	2,048
4	4,096
8	8,192
16	16,384
32	32,768
64	65,536
128	131,072
256	262,144
512	524,288

If you are converting for a download estimate, remember that network speeds are quoted in bits per second (Mbps) while file sizes are bytes — 100 Mbps moves about 12.5 MB per second. Use the download time calculator for that math.

Results are computed locally in your browser. Binary (1024) is what Windows and most disk tools show; decimal (1000) is what drive and cloud vendors print on the box — the same file can honestly be described by both numbers.

Core facts

Binary answer	1,024 MB (2¹⁰) — Windows, Linux tools, most file managers
Decimal answer	1,000 MB (10³) — carriers, drive labels, cloud quotas, macOS
Exact bytes	1 GB = 1,000,000,000 B (decimal) · 1 GiB = 1,073,741,824 B (binary)
Reference	IEC 80000-13 defines KiB/MiB/GiB for the 1,024 version; “GB” is decimal by SI

Four quick anchors to remember

1 GB = 1,024 MB · 1 MB = 1,024 KB · 1 TB = 1,024 GB (all binary). In decimal the same names step by a clean thousand. If you can only remember one thing: the binary version is always about 2.4% larger, and three steps of crossing between conventions compound to roughly 7%.

Why your phone, drive and plan disagree

A 128 GB phone holds decimal 128,000,000,000 bytes of flash, minus the system partition, then reports its free space in binary GiB — so it shows around 119 GiB. A 2 TB drive shows 1.81 TiB on a Mac and 1,862 GiB on Windows. A 50 GB mobile plan is 50,000 MB of traffic, which a binary meter records as 48.8 GiB. Three different products, one single naming inconsistency.

Converting at scale

For a rough mental conversion, treat 1 GB as 1,000 MB and subtract 2.4% for each convention crossing. For exact work — partitions, quotas, billing disputes — convert to bytes first: decimal GB × 10⁹, binary GiB × 2³⁰. The calculator above does both lines at once so you never have to choose before you see the numbers.