← All tools
GNW / Free calculator
Storage Capacity Calculator
Estimate file capacity after allowing space for your operating system, apps and other content.
Enter your values and choose Calculate.
Estimates only. Values are calculated in your browser and are not sent or saved by this tool.
How capacity is estimated
Usable GB = capacity × (1 − reserved percentage ÷ 100). File count = usable GB × 1,000 ÷ average file size in MB, rounded down.
At 256 GB, 15% reserved space and 5 MB per file, the estimate is 43,520 files. Decimal GB differs from the binary GiB figure some operating systems display: 1 GB is 1 billion bytes; 1 GiB is 1,073,741,824 bytes.
Choose a realistic file size
Photo, video and game sizes vary widely. Use a sample from your own files. This calculator does not inspect your device, measure free space or predict compression.