MB to GB Conversion: 1000 or 1024?
Why does 1,000 MB equal 1 GB on a retail box but only 0.976 GB in Windows? Explore the difference between decimal (SI base 10) and binary (IEC base 2) standards, and learn when to divide by 1,000 versus 1,024.
Both are correct depending on context. Divide by 1,000 for hard drives, SSDs, USB flash drives, and macOS (Decimal SI standard). Divide by 1,024 for computer RAM, GPU VRAM, and Windows file explorer (Binary IEC standard).
Interactive Decimal vs Binary Dual Calculator
Enter any Megabyte amount to see the side-by-side decimal (÷1,000) and binary (÷1,024) calculation with exact discrepancy percentage.
1000 vs 1024 Reference Comparison Table
Observe how the apparent gap widens as file sizes scale from small files to massive storage drives.
| Megabytes (MB) | Decimal GB (÷1000) | Binary GiB (÷1024) | Discrepancy |
|---|---|---|---|
| 500 MB | 0.500 GB | 0.488 GiB | -2.4% |
| 1,000 MB | 1.000 GB | 0.976 GiB | -2.4% |
| 1,024 MB (1GB RAM) | 1.024 GB | 1.000 GiB | Exact RAM Match |
| 4,096 MB (4GB RAM) | 4.096 GB | 4.000 GiB | Exact RAM Match |
| 8,192 MB (8GB RAM) | 8.192 GB | 8.000 GiB | Exact RAM Match |
| 16,384 MB (16GB RAM) | 16.384 GB | 16.000 GiB | Exact RAM Match |
| 100,000 MB (100GB Drive) | 100.000 GB | 93.132 GiB | -6.87 GB (~6.9%) |
| 500,000 MB (500GB SSD) | 500.000 GB | 465.661 GiB | -34.34 GB (~6.9%) |
| 1,000,000 MB (1TB Drive) | 1,000.000 GB | 931.322 GiB | -68.68 GB (~6.9%) |
| 2,000,000 MB (2TB Drive) | 2,000.000 GB | 1,862.645 GiB | -137.35 GB (~6.9%) |
The 'Missing Storage' Mystery in Windows Explained
When you purchase a brand-new 1 Terabyte (1,000 GB) SSD, you might be surprised to see Windows reporting only 931 GB of usable space. Your drive is not defective, and the manufacturer did not deliver less storage than advertised.
The drive manufacturer built exactly 1,000,000,000,000 bytes (10¹² bytes). When Microsoft Windows reads the drive, it divides those bytes by 1,024 three times (1,024³ = 1,073,741,824 bytes per Gibibyte). The math results in 931.32 GiB. Because Windows labels this binary number with the decimal unit 'GB', approximately 69 Gigabytes appear to vanish into thin air!
Related Storage Calculators & Guides
Frequently Asked Questions
Is 1 GB equal to 1,000 MB or 1,024 MB?
Both answers are technically correct in their respective domains. In the International System of Units (SI), 1 GB (Gigabyte) = 1,000 MB. In computer architecture and the International Electrotechnical Commission (IEC) standard, 1 GiB (Gibibyte) = 1,024 MiB. Computer memory (RAM) always uses 1,024, whereas storage drive manufacturers use 1,000.
Why do hard drives show less space in Windows than advertised on the box?
Drive manufacturers calculate capacity in decimal units (1 TB = 1,000,000,000,000 bytes). Microsoft Windows calculates storage in binary units (dividing by 1,024 three times: 1,073,741,824). Because Windows uses binary math but mislabels the output with the decimal symbol 'GB', a 1 TB drive appears as approximately 931 GB in Windows Explorer.
Does Apple macOS use 1,000 or 1,024 to measure storage?
Starting with Mac OS X Snow Leopard (10.6), Apple switched macOS to standard decimal (base 10) calculation. In macOS, 1 GB = 1,000 MB. Therefore, a 1 TB SSD in macOS displays as exactly 1 TB, perfectly matching the manufacturer's packaging.
What is the difference between GB and GiB?
GB (Gigabyte) represents 1,000,000,000 bytes (10⁹ decimal). GiB (Gibibyte) represents 1,073,741,824 bytes (2³⁰ binary). The GiB unit was officially introduced by the IEC in 1998 to eliminate confusion between decimal storage and binary memory.
When should I divide by 1,000 versus 1,024?
Divide by 1,000 when calculating hard drive, SSD, SD card, cloud storage (Google Drive, Dropbox, iCloud), or mobile network data caps. Divide by 1,024 when calculating computer RAM, GPU video memory (VRAM), or Windows partition layouts.