How Many MB in a GB? 1,000 vs 1,024 Explained

By KT Apps · Updated October 16, 2026

The short answer

• Decimal (base 10): 1 GB = 1,000 MB. Drive and memory card makers use this, and so do many search engines and converters.
• Binary (base 2): 1 GB = 1,024 MB. Windows and many older programs report sizes this way, and computer memory is built in these steps.

The difference is small for one step, 2.4%, but it grows at each level: about 4.9% at the megabyte level, about 7.4% at the gigabyte level and about 10% at the terabyte level, when you compare the full byte counts.

Why there are two answers

Computers address memory in powers of two. 2 to the power of 10 is 1,024, close enough to 1,000 that early engineers borrowed the metric prefix kilo for it. A kilobyte became 1,024 bytes, a megabyte 1,024 kilobytes, and so on.

Storage manufacturers, on the other hand, use the prefixes in their normal metric sense: kilo is 1,000, mega is 1,000,000 and giga is 1,000,000,000. To end the confusion, standards bodies introduced separate binary names: kibibyte (KiB), mebibyte (MiB), gibibyte (GiB) and tebibyte (TiB). So strictly, 1 GiB = 1,024 MiB and 1 GB = 1,000 MB. In everyday software, though, you will still see GB written where GiB is meant.

Which system does your device use?

• Hard drives, SSDs, USB sticks and memory cards: decimal on the packaging.
• Windows File Explorer: binary values labelled KB, MB and GB.
• macOS (since 2009), iPhone and iPad: decimal, so a file or drive size matches the packaging figure more closely.
• RAM: binary. An 8 GB memory module holds 8 × 1,024 × 1,024 × 1,024 bytes.
• Mobile data plans: varies by carrier, so check your carrier's terms if the exact figure matters.

This is why the same file can appear as slightly different sizes on a Mac and on a Windows PC, without anything being wrong.

How to convert MB to GB by hand

1. Decide which system you need. For a drive or card you are buying, use decimal. To match what Windows reports, use binary.
2. To go from MB to GB, divide by 1,000 (decimal) or 1,024 (binary).
3. To go from GB to MB, multiply by 1,000 (decimal) or 1,024 (binary).
4. For two steps at once, such as MB to TB, divide twice.

Worked examples

• 5,000 MB to GB: 5,000 ÷ 1,000 = 5 GB decimal, or 5,000 ÷ 1,024 ≈ 4.88 GB binary.
• 2.5 GB to MB: 2.5 × 1,000 = 2,500 MB decimal, or 2.5 × 1,024 = 2,560 MB binary.
• How many 700 MB files fit on a 64 GB card? In decimal, 64,000 ÷ 700 ≈ 91 files. In practice, a little less, because the file system uses some space.

Do not forget bits and bytes. A lowercase b means bits and an uppercase B means bytes, and there are 8 bits in a byte. A 100 Mbps connection moves at most 12.5 MB per second, before overheads.

Mental maths, search engine, spreadsheet or converter?

Mental maths

Dividing by 1,000 is easy in your head, and it is close enough for rough estimates. For anything where a few percent matters, such as whether a backup will fit, do the exact calculation.

Search engine

Typing "5000 MB to GB" into a search box gives an instant answer, but most search converters use decimal units unless you ask for MiB and GiB. That is fine for packaging figures and confusing if you are comparing with Windows.

Spreadsheet

Good for many values at once. With a size in MB in cell A1, =A1/1024 gives binary GB and =A1/1000 gives decimal GB. Label which is which in the column header.

A unit converter app

Handy when you convert often or need to go across several steps, such as bytes to TB, without counting zeros. Check which system the converter uses before you rely on it.

How to convert MB to GB in Bitcon

Bitcon uses the 1,024-based steps, so its answers match what Windows and many programs report:

1. Open the Convert tab and type the number into Enter Value.
2. Tap the MB → GB Quick Conversion button, or choose MB as the From Unit and GB as the To Unit yourself. Use the swap button to go from GB to MB instead.
3. Read the Conversion Result, which updates as you type, and tap Copy if you need the number elsewhere.
4. Use the precision button in the top bar to set the number of decimal places, or switch on scientific notation for very large or small values.
5. To see one value in several units at once, open Compare Units and select the units you want, for example MB, GB and TB.
6. Save a pair you use often on the Templates tab. Earlier conversions are kept on the History tab, where you can reuse one with a tap.

Bitcon does not have a separate decimal mode. When you need the decimal figure, for example to match a drive's packaging, divide by 1,000 instead, or enter the size in bytes, as explained in our guide to why a 1 TB drive shows 931 GB.

Frequently asked questions