Three calculators for sizing disk space and transfer when running an image server.
Estimate required disk space from original files and backup copies.
Estimate extra storage needed for separately saved thumbnails.
Estimate origin-server transfer from views, MB per view, and CDN cache hit rate.
The default values provide a concrete example of how to interpret each result. Display units are binary, where 1 KB equals 1024 bytes.
10,000 × 2.8MB × 2 copies
10,000 × 70KB × 1 copyRequired storage 54.69GB
Thumbnail cache 683.59MBA copy count of two means two total stored copies including the primary. Use three for a primary plus two backups.
50,000 views × 1.2MB × (1 - 60% cache hit)Monthly origin transfer 23.44GBReplace the cache-hit input regularly with the measured value from your CDN dashboard.
The calculator uses plain multiplication. Plug in real folder numbers to verify it yourself.
# 0) install bc (a calculator) if missing
sudo apt install -y bc
# 1) save this as capacity.sh and run it (bash capacity.sh)
#!/usr/bin/env bash
count=$(find ~/uploads -type f | wc -l) # auto-count files
avg=2.6 # average file size (MB) — from du -sh
variants=3 # number of thumbnail sizes (e.g. S/M/L)
# originals = count × average
original=$(echo "$count * $avg" | bc)
# thumbnails = count × variants × (about 20% of average)
thumbs=$(echo "$count * $variants * $avg * 0.2" | bc)
echo "originals ${original}MB + thumbs ${thumbs}MB"
# → e.g. "originals 12532MB + thumbs 7519MB"
# budget 1.5–2× of the total to include backups