データ容量換算

GB から MB、TB から GB、GiB から GB に換算します。十進接頭辞（kB、MB、GB、TB）と二進接頭辞（KiB、MiB、GiB、TiB）を区別し、ビットとバイトにも対応します。

更新日 2026年9月29日検証済みの例：5

値

変換元の単位で数値を入力するか、単位付きの数値を入力します

変換元

変換先

試す

変換後の値

有効桁数：12；最も近い値へ、等距離ならゼロから遠い値へ

単位換算: 1 GiB = 1,073.741824 MB
換算係数: 1,073.741824
正確さ: 正確

1 GiBは正確に1,073.741824 MBです。

各2進接頭辞は対応する10進接頭辞よりどれだけ大きいか

1 GiBを各データ容量単位で表示行数：25

単位	値	定義
bit	8,589,934,592	基本単位
nibble	2,147,483,648	1 nibble = 4 bit、正確な値
byte (B)	1,073,741,824	1 B = 8 bit、正確な値
kilobyte (kB)	1,073,741.824	1 kB = 8,000 bit、正確な値
メガバイト (MB)	1,073.741824	1 MB = 8,000,000 bit、正確な値
ギガバイト (GB)	1.073741824	1 GB = 8,000,000,000 bit、正確な値
テラバイト (TB)	0.001073741824	1 TB = 8,000,000,000,000 bit、正確な値
petabyte (PB)	0.000001073741824	1 PB = 8 × 10¹⁵ bit、正確な値
exabyte (EB)	1.073741824 × 10⁻⁹	1 EB = 8 × 10¹⁸ bit、正確な値
zettabyte (ZB)	1.073741824 × 10⁻¹²	1 ZB = 8 × 10²¹ bit、正確な値
yottabyte (YB)	1.073741824 × 10⁻¹⁵	1 YB = 8 × 10²⁴ bit、正確な値
kibibyte (KiB)	1,048,576	1 KiB = 8,192 bit、正確な値
mebibyte (MiB)	1,024	1 MiB = 8,388,608 bit、正確な値
gibibyte (GiB)	1	1 GiB = 8,589,934,592 bit、正確な値
tebibyte (TiB)	0.0009765625	1 TiB = 8,796,093,022,208 bit、正確な値
pebibyte (PiB)	9.536743 × 10⁻⁷	1 PiB = 9.007199254740992 × 10¹⁵ bit、正確な値
exbibyte (EiB)	9.313226 × 10⁻¹⁰	1 EiB = 9.223372036854775808 × 10¹⁸ bit、正確な値
zebibyte (ZiB)	9.094947 × 10⁻¹³	1 ZiB = 9.4447329657392904274 × 10²¹ bit、正確な値
yobibyte (YiB)	8.881784197 × 10⁻¹⁶	1 YiB = 9.6714065569170333976 × 10²⁴ bit、正確な値
kilobit (kbit)	8,589,934.592	1 kbit = 1,000 bit、正確な値
megabit (Mbit)	8,589.934592	1 Mbit = 1,000,000 bit、正確な値
gigabit (Gbit)	8.589934592	1 Gbit = 1,000,000,000 bit、正確な値
terabit (Tbit)	0.008589934592	1 Tbit = 1,000,000,000,000 bit、正確な値
kibibit (Kibit)	8,388,608	1 Kibit = 1,024 bit、正確な値
mebibit (Mibit)	8,192	1 Mibit = 1,048,576 bit、正確な値

計算方法 S

gibibyteからbitへ換算
$1\ \text{GiB} \times 8{,}589{,}934{,}592\ \tfrac{\text{bit}}{\text{GiB}} = 8{,}589{,}934{,}592\ \text{bit}$
1 GiB = 8,589,934,592 bit、正確な値
bitからメガバイトへ換算
$8{,}589{,}934{,}592\ \text{bit} \div 8{,}000{,}000\ \tfrac{\text{bit}}{\text{MB}} = 1{,}073.741824\ \text{MB}$
1 MB = 8,000,000 bit、正確な値
統合した換算係数
$1\ \text{GiB} = \frac{8{,}589{,}934{,}592}{8{,}000{,}000}\ \text{MB} = 1{,}073.741824\ \text{MB}$
両方の単位の定義が正確で、変換後の値は有限小数なので、表示されるすべての桁が正確です。

データ容量換算について

Data sizes use two sets of prefixes. The decimal ones follow the SI: 1 kB = 1,000 bytes, 1 MB = 10⁶ and 1 GB = 10⁹ bytes. The binary ones, approved by the IEC in December 1998 and now part of IEC 80000-13, step by 1,024: 1 KiB = 1,024 bytes, 1 MiB = 2²⁰ and 1 GiB = 2³⁰ bytes. A byte is 8 bits, and every conversion between these units is exact.

The default converts 1 GiB to 1,073.741824 MB. The same gap explains why a new drive looks smaller: a 1 TB drive holds 10¹² bytes, which software counting in binary units shows as 931.32 GiB, often labelled “931 GB”.

The gap grows with each prefix: 2.4% at kilo, 7.37% at giga, 9.95% at tera and 20.9% at yotta. Memory chips come in powers of two, so RAM sizes are binary even when written GB, while drive makers and network speeds use decimal prefixes.

計算例

1 GiB in MB

値: 1 GiB
変換元: gibibyte (GiB)
変換先: megabyte (MB)

変換後の値: 1,073.741824 MB
正確さ: 正確

照合元：2³⁰ bytes = 1,073,741,824 bytes (IEC 80000-13); ÷ 10⁶

A 1 TB drive in GiB

値: 1 TB
変換元: terabyte (TB)
変換先: gibibyte (GiB)

変換後の値: 931.322574615 GiB

照合元：10¹² / 2³⁰ = 244140625/262144, a terminating decimal (Python fractions)

1 KiB in kB

値: 1 KiB
変換元: kibibyte (KiB)
変換先: kilobyte (kB)

変換後の値: 1.024 kB

照合元：1024 bytes / 1000 bytes

Largest gap: 1 YiB in YB

値: 1 YiB
変換元: yobibyte (YiB)
変換先: yottabyte (YB)

変換後の値: 1.20892581961 YB

照合元：2⁸⁰ / 10²⁴ = 1.208925819614629174706176 exactly (Python fractions)

よくある質問

Why does my 1 TB drive show only 931 GB?

Because the maker and the operating system count differently. The drive's 1 TB is 10¹² bytes; Windows divides by 2³⁰ and shows 931.32 while labelling it GB. Nothing is missing, since 10¹² ÷ 1,073,741,824 = 931.32; formatting and recovery partitions take a little more. macOS has counted in decimal since OS X 10.6 and shows the same drive as 1 TB.

Is 1 GB 1,000 MB or 1,024 MB?

Under the SI and IEC 80000-13, 1 GB is exactly 1,000 MB (10⁹ bytes), and the binary unit is 1 GiB = 1,024 MiB (2³⁰ bytes). Drive makers and macOS use the decimal meaning; RAM and Windows use the binary one while writing GB. The “1.44 MB” floppy disk mixed the two: 1,440 × 1,024 bytes.

How many bits are in a byte?

Eight. IEC 80000-13 defines the byte as 8 bits, also called an octet. File sizes are counted in bytes (B) and network speeds in bits per second (bit/s), so a 100 Mbit/s connection moves at most 12.5 MB per second; a capital B marks bytes.

What is a GiB?

A gibibyte, 2³⁰ = 1,073,741,824 bytes. The IEC created the binary prefixes kibi, mebi, gibi and tebi so that kilo, mega and giga could keep their SI meanings of 10³, 10⁶ and 10⁹. Many Linux tools and technical specifications use GiB; Windows shows the same quantity labelled GB.

How many GB are in 1 TB?

1,000 GB in decimal units, which is how drives are sold. In binary units 1 TiB is 1,024 GiB, and a decimal 1 TB is 931.32 GiB. The converter keeps TB, TiB, GB and GiB separate, so you can see that 1 TiB is 1,099.51 GB, about 10% more than 1 TB.

「データ容量換算」の精度はどのくらいですか？

精度は入力値と計算方法の前提に依存します。十進演算には有効数字50桁を使いますが、推定、数値計算手法、元データの精度はそれより低い場合があります。表示の丸め処理でこれらの制約がなくなるわけではありません。独立した出典の解答と照合した計算例：5。例えば、「1 GiB in MB」は2³⁰ bytes = 1,073,741,824 bytes (IEC 80000-13); ÷ 10⁶と照合しています。

この計算方法の出典は何ですか？

NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors; NIST Handbook 44, Appendix C — General tables of units of measurement; NIST — Prefixes for binary multiples (IEC 80000-13).

この計算機について

\begin{gathered} x_{\text{to}} = x_{\text{from}} \times \dfrac{f_{\text{from}}}{f_{\text{to}}} \\ f = \text{one unit expressed in } \text{bit} \end{gathered}

出典

出典と照合済み

この計算機には、独立した出典の解答を使った計算例が 5 件あります。テストに組み込まれており、ここでも実行できます。

各2進接頭辞は対応する10進接頭辞よりどれだけ大きいか

gibibyteからbitへ換算

bitからメガバイトへ換算

統合した換算係数