Estimate decimal usable drive capacity after reserving whole drives for a stated parity or mirror allowance.
A transparent estimate based on the values you enter. No account is needed.
Use the tool
Estimate decimal usable drive capacity after reserving whole drives for a stated parity or mirror allowance.
How the estimate works
Simplified usable capacity = (installed drives − drive-equivalents reserved) × capacity per drive. Decimal TB is used.
Check a product or part
Enter a product, exact model or part number. Retailer searches are optional and open only when you select a link. Check manufacturer references, fit, condition, delivery and seller terms before buying.
Search links open the chosen marketplace. eBay examples are Australian snapshots; check listing details on the retailer site. eBay Partner Network links may earn Vyonetix a commission.
Explore eBay AU listing examples
Australian listing examples are shown only when Australia is selected. Use the retailer searches for your chosen market.
These are dated API search matches, not a verified fit or recommendation. Checked: 30 Oct 2026 07:20 UTC. Listings may change or disappear.
Synology RackStation RS812+ Network Attached Storage NAS No HDD 4x Caddy's
eBay AU search match checked 30 Oct 2026 07:20 UTC. Compare full model, condition, seller, shipping and return details.
eBay Partner Network links may earn Vyonetix a commission. Verify exact product details with the seller and manufacturer.
About this tool
Plan a rough NAS capacity using the number of installed drives, capacity per drive, and the number of drive-equivalents reserved for redundancy. The result uses decimal terabytes and represents a simplified usable-capacity estimate. It does not model filesystem metadata, hot spares, RAID implementation differences, rebuild risk, snapshots, compression or backup copies. Redundancy is not a backup. Confirm the exact array level and vendor capacity calculator before selecting hardware, and keep an independent backup of data you cannot replace.
Frequently asked questions
Are these results guaranteed to fit?
No. Search matching and user-entered calculations do not establish compatibility. Verify part codes, dimensions and manufacturer guidance.
Are prices or stock shown?
No. Retailer pages show their current terms after you open them. This tool does not scrape or promise live prices or availability.