Disk Partition Calculator
Integer partition calculator for NTFS, FAT32, exFAT
Result
102,407 MB102,796 MB102,400 MBCommon partition size reference
| Target | NTFS (MB) | FAT32 (MB) | exFAT (MB) | Shown as |
|---|---|---|---|---|
| 10 GB | 10,245 | 10,276 | 10,240 | 10.0 GB |
| 20 GB | 20,482 | 20,556 | 20,480 | 20.0 GB |
| 30 GB | 30,726 | 30,836 | 30,720 | 30.0 GB |
| 50 GB | 51,208 | 51,396 | 51,200 | 50.0 GB |
| 100 GB | 102,407 | 102,796 | 102,400 | 100.0 GB |
| 150 GB | 153,606 | 154,196 | 153,600 | 150.0 GB |
| 200 GB | 204,806 | 205,596 | 204,800 | 200.0 GB |
| 300 GB | 307,204 | 308,396 | 307,200 | 300.0 GB |
| 500 GB | 512,002 | 513,996 | 512,000 | 500.0 GB |
How it works
Why isn't the partition shown as an integer?
Windows calculates storage in binary (base 1024), while disk vendors label capacity in decimal, so entering 102400 MB shows 99.9 GB. The file system also reserves hidden space for boot sectors and metadata, so compensation is needed to get an integer display.
NTFS integer partition
NTFS partitions are allocated by whole cylinders. Each cylinder is 512 bytes × 255 heads × 63 sectors = 7.84423828125 MB:
Cylinders = ⌈ GB × 1024 ÷ 7.84423828125 ⌉
⌈ cylinders × 7.84423828125 ⌉
FAT32 integer partition
FAT32 uses the classic linear compensation formula, adding 4 MB per GB (the first GB is not counted):
1024 × GB + 4 × (GB − 1)
Example: 100 GB → 102796 MB (FAT32)
exFAT integer partition
exFAT has no widely accepted compensation formula like NTFS/FAT32, so the simplest ×1024 conversion is used:
1024 × GB
These formulas target the "New Simple Volume" flow in Windows 10/11 Disk Management. Different tools, 4K alignment, and GPT/MBR can cause a few MB of variance.
Something broken or missing?
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