GB to MB Converter

gigabytes to megabytes — quick reference

The formula, worked line by line

A gigabyte is exactly one thousand megabytes in decimal SI, so this is one multiplication and the constant carries no rounding of its own. The same factor of a thousand joins every rung of the decimal ladder, from kilobytes up through terabytes, which is why the whole system amounts to a decimal point moving three places at a time.

The binary answer, when you need it, pivots through bytes rather than through a second rounded factor. Multiply gigabytes by 1,000,000,000 to get bytes, then divide by 1,048,576 for mebibytes or by 1,073,741,824 for gibibytes. Doing it in one pass through bytes is what stops small errors compounding once you get to the terabyte end of the scale.

MB = GB × 1,000
bytes = GB × 1,000,000,000
MiB = GB × 1,000,000,000 ÷ 1,048,576
MB/s = Mbps ÷ 8

Scaling up follows the identical single step. A 64 GB phone holds 64,000 MB, a 128 GB one holds 128,000 MB, and a 2 TB drive holds 2,000 GB or 2,000,000 MB.

Where the arithmetic stops being trivial is when a device reports in binary while still writing GB: that 64 GB phone reads as 59.60 GB in Windows, because 64,000,000,000 ÷ 1,073,741,824 = 59.60. The 4.40 GB difference is purely a change of ruler, and it sits on top of whatever the operating system and preinstalled apps genuinely occupy.

How to use the GB to MB converter

Gigabytes are how storage and connectivity get sold: a 5 GB monthly plan, a 128 GB phone, a 2 TB external drive, a 50 GB game. Almost everything you then measure against them is quoted in megabytes. Mail servers cap attachments at 25 MB. App updates arrive at 80 MB or 300 MB. A usage screen counts today in megabytes. A hotel or airline captive portal doles out a few hundred megabytes at a time.

This converter multiplies gigabytes by 1,000 so both sides of that comparison sit in the same unit and the answer is a whole number you can hold in your head. Swap runs it the other way when a file listing hands you gigabytes and the limit you are checking is written in megabytes.

The most common reason to do this conversion is budgeting a mobile data allowance, and the useful move is turning the monthly figure into a daily one, a number you can genuinely check against a phone usage screen at lunchtime.

The daily figure matters because allowances are consumed unevenly and the monthly number tells you nothing until the month is nearly over. Carriers define the gigabyte decimally, so these are the real numbers behind the bill rather than an approximation of them.

The multiplier is 1,000 because this converter uses the decimal SI definition: 1 GB = 1,000 MB = 1,000,000 KB = 1,000,000,000 bytes. That is what carriers, drive makers and spec sheets mean when they print GB. If you genuinely need the binary answer, 5 GB is 4,768 MiB rather than 5,000 MB — and it is worth writing the unit out in full so the next person reading your spreadsheet knows which one you meant.

Megabits are not megabytes

One more unit lives next door and is easy to trip over. Storage counts bytes; connection speeds count bits, and there are eight bits to a byte. The capital B in MB and the lower-case b in Mb are doing all the work in that distinction, which is why an eightfold surprise is so common when someone times a download against their advertised speed.

Every gigabytes value, worked out

73 common gigabytes figures each get their own page, with the answer, the arithmetic, what rounding costs, and the nearest real-world reference point on the scale.

Questions people ask