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GB to MB Conversion Calculator

Converts a quantity of digital storage between bits, bytes and the decimal and binary multiples, showing the byte count exactly and explaining why a 1 TB drive reports as 931 GiB.

Converted amount
1,000.000000
Digital Storage Converter
Bytes
1000000000
Bits
8000000000
From system
decimal (powers of 1000)
To system
decimal (powers of 1000)
Difference between the two systems
0.0000 %
Worked out from BIPM, The International System of Units (SI Brochure), SI prefixes and 1 other source.

Your figures

Updates as you type
Applies to the converted amount. The byte count is always exact.

How this is worked out

3 steps
  1. 1 GB = 1000000000 bytes exactly
  2. 1 GB = 1000000000 bytes; 1 MB = 1000000 bytes
  3. 1 × 8000000000 ÷ 8000000 = 1000 MB

Its 3 worked examples are re-run on every release, last on 15 September 2026. What changed

Sources and references

2 sources
BIPM, The International System of Units (SI Brochure), SI prefixes
kilo, mega, giga and tera are decimal: 10³, 10⁶, 10⁹, 10¹².
NIST, Prefixes for binary multiples
kibi, mebi, gibi and tebi are exact powers of two: 2¹⁰, 2²⁰, 2³⁰, 2⁴⁰. Quoted here because the IEC 80000-13 clause text is paywalled.

What this calculator does

Converts a quantity of digital storage between bits, bytes and the decimal and binary multiples, showing the byte count exactly and explaining why a 1 TB drive reports as 931 GiB.

How to use GB to MB Conversion Calculator

Enter Amount, From, To and Decimal places. The calculator checks the values, applies the stated method, and updates the result without saving your figures.

What the result means

The result includes Converted amount, Bytes, Bits, From system, To system and Difference between the two systems. Review the visible working and any warnings before using the answer for a decision.

Method and checks

The method cites BIPM, The International System of Units (SI Brochure), SI prefixes; NIST, Prefixes for binary multiples. Its 3 built-in worked examples are checked on every full test run. The initial answer and working are rendered on the server, so they remain readable without JavaScript.

Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.

Embed this calculator on your website

Copy this code into any page. The calculator appears with the figures currently entered, sizes itself to fit, and a small credit line links back here. Free, no account, no ads inside it, no tracking of your readers. Set your own figures and fixed fields; Personal removes the credit line, sets your colour and shows you which sites use it.

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