Data Storage Converter: GB, MB, TB & GiB
Updated · Free · No sign-up · Runs in your browser
Convert data sizes between bits, bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes — using either decimal units (1 GB = 1,000 MB) or binary units (1 GiB = 1,024 MiB).
It also estimates how long a download takes at your connection speed in Mbps.
- Bits
- 8,000,000,000 bit
- Bytes
- 1,000,000,000 B
- KB
- 1,000,000 KB
- MB
- 1,000 MB
- TB
- 0.001 TB
- PB
- 0.000001 PB
Download time (theoretical)
About 1 min 20 sec. Real downloads are usually slower because of network overhead and server speed.
Why your drive looks smaller in Windows
Drive makers use decimal units (1 GB = 10⁹ bytes); Windows reports binary units (1 GiB = 2³⁰ bytes) but labels them "GB".
| Advertised | Shown in Windows |
|---|---|
| 128 GB | 119.2 GB |
| 256 GB | 238.4 GB |
| 512 GB | 476.8 GB |
| 1 TB | 931.3 GB |
| 2 TB | 1,863 GB |
| 4 TB | 3,725 GB |
GB to MB chart
| GB | MB (decimal) | MiB (binary) |
|---|---|---|
| 0.5 GB | 500 MB | 512 MiB |
| 1 GB | 1,000 MB | 1,024 MiB |
| 2 GB | 2,000 MB | 2,048 MiB |
| 5 GB | 5,000 MB | 5,120 MiB |
| 10 GB | 10,000 MB | 10,240 MiB |
| 50 GB | 50,000 MB | 51,200 MiB |
| 100 GB | 100,000 MB | 102,400 MiB |
Worked examples
1 TB drive in Windows
- 1,000,000,000,000 bytes ÷ 1,073,741,824
→ 931.32 GB
5 GB to MB (decimal)
- 5 × 1,000
→ 5,000 MB
5 GiB to MiB (binary)
- 5 × 1,024
→ 5,120 MiB
2 GB file at 100 Mbps
- 2,000 MB × 8 = 16,000 megabits
- 16,000 ÷ 100
→ 160 seconds (2 min 40 sec)
Decimal vs binary: 1000 or 1024?
Storage manufacturers, network speeds and macOS use decimal SI prefixes: 1 KB = 1,000 bytes, 1 MB = 1,000 KB, 1 GB = 1,000 MB.
Windows and RAM sizes use binary multiples of 1,024 (officially KiB, MiB, GiB), even when Windows writes "GB". That is why the same drive shows a smaller number on a PC.
Bits vs bytes
- 1 byte = 8 bits
- Internet speed is quoted in megabits per second (Mbps); file sizes are in megabytes (MB).
- Download time ≈ file size in MB × 8 ÷ speed in Mbps
Frequently asked questions
How many MB are in a GB?
In decimal units, 1 GB = 1,000 MB. In binary units, 1 GiB = 1,024 MiB. Phone plans and drive labels use 1,000; Windows uses 1,024.
How many GB are in a TB?
1 TB = 1,000 GB (decimal) or 1 TiB = 1,024 GiB (binary).
Why does my 1 TB hard drive show only 931 GB?
The drive holds 10¹² bytes. Windows divides by 1,024³ and still labels it "GB", so it shows 931.3 GB. No space is missing.
What is the difference between GB and GiB?
GB (gigabyte) is 10⁹ bytes; GiB (gibibyte) is 2³⁰ = 1,073,741,824 bytes, about 7.4% more.
How long does it take to download 1 GB?
At 100 Mbps, 1 GB (8,000 megabits) takes about 80 seconds in theory. Real downloads are slower because of overhead and server limits.
Is Mbps the same as MB/s?
No. Mbps is megabits per second; MB/s is megabytes per second. Divide Mbps by 8 to get MB/s, so 100 Mbps ≈ 12.5 MB/s.