How this calculator works
Each step up the scale multiplies by 1,000 in decimal (SI) units — kilobyte, megabyte, gigabyte, terabyte — so 1 GB is 1,000 MB and 1 TB is 1,000 GB. Computers count memory in powers of two, so they also use binary units where each step is 1,024: 1 GiB (gibibyte) is 1,024 MiB. The official names for the binary units come from the IEC and NIST, but many programs still write “GB” when they mean GiB.
The difference grows at each step: 2.4% at kilobytes, about 7% at gigabytes and almost 10% at terabytes. That gap is the “missing” space on a new drive.
Assumptions and tips
- Internet speeds are quoted in bits per second (Mbps), not bytes — divide by 8 to get megabytes per second.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Amount | 1 |
| From | GB |
| To | MB |
| Units | Decimal — 1 GB = 1,000 MB (drives, phones, internet plans) |
| Result | Value |
|---|---|
| In MB | 1,000 MB |
| Bytes | 1,000,000,000 bytes |
| Bits | 8,000,000,000 bits |
| Same size in binary MiB | 953.674 MiB |
All units:
- 1,000,000,000 B
- 1,000,000 KB
- 1,000 MB
- 1 GB
- 0.001 TB
- 0.000001 PB
Step by step:
- Decimal units: each step is × 1000
- GB → MB is 1 step down, so multiply by 1000^1 = 1,000
- 1 × 1,000 = 1,000 MB
Common data size conversions (decimal units)
Storage makers’ decimal units, calculated with this tool.
| Convert | Answer |
|---|---|
| 1 GB → MB | 1,000 MB |
| 1 TB → GB | 1,000 GB |
| 1 MB → KB | 1,000 KB |
| 500 MB → GB | 0.5 GB |
| 1500 MB → GB | 1.5 GB |
| 2 TB → GB | 2,000 GB |
| 256 GB → TB | 0.256 TB |
| 4.7 GB → MB | 4,700 MB |
| 1 GB → KB | 1,000,000 KB |
| 1 PB → TB | 1,000 TB |
Common mistakes to avoid
- Mixing bits and bytes: a 100 Mbps connection downloads about 12.5 MB per second.
- Expecting a 1 TB drive to show 1,000 GB in Windows — it shows about 931 because Windows uses binary units.
Frequently asked questions
How many megabytes are in a gigabyte?
1,000 MB in decimal units, or 1,024 MiB in binary units.
How many GB is 1 TB?
1,000 GB — but Windows shows a 1 TB drive as about 931 “GB” because it uses binary units.
How many KB in an MB?
1,000 KB (or 1,024 KiB in binary).
Is 1 GB 1,000 or 1,024 MB?
Both are used. Storage and network makers use 1,000; operating systems and RAM often use 1,024 (properly written GiB).
Sources
Built and reviewed by Anirban Kundu, Creator & Editor · M.Sc Physics, 20 years teaching science