NAS RAID Capacity & Drive Count Calculator

Capacity	Exact model	Price / drive	Recording method	Official compatibility	Warranty (years)	Annual failure rate AFR (%)	Seller URL	Price checked date	Official compatibility source URL	AFR source URL
8 TB	Exact model 8 TB	Price / drive 8 TB	Recording method 8 TB	Official compatibility 8 TB	Warranty 8 TB	Annual failure rate 8 TB	Seller URL 8 TB	Price checked date 8 TB	Official compatibility source URL 8 TB	AFR source URL 8 TB
12 TB	Exact model 12 TB	Price / drive 12 TB	Recording method 12 TB	Official compatibility 12 TB	Warranty 12 TB	Annual failure rate 12 TB	Seller URL 12 TB	Price checked date 12 TB	Official compatibility source URL 12 TB	AFR source URL 12 TB
16 TB	Exact model 16 TB	Price / drive 16 TB	Recording method 16 TB	Official compatibility 16 TB	Warranty 16 TB	Annual failure rate 16 TB	Seller URL 16 TB	Price checked date 16 TB	Official compatibility source URL 16 TB	AFR source URL 16 TB
20 TB	Exact model 20 TB	Price / drive 20 TB	Recording method 20 TB	Official compatibility 20 TB	Warranty 20 TB	Annual failure rate 20 TB	Seller URL 20 TB	Price checked date 20 TB	Official compatibility source URL 20 TB	AFR source URL 20 TB
24 TB	Exact model 24 TB	Price / drive 24 TB	Recording method 24 TB	Official compatibility 24 TB	Warranty 24 TB	Annual failure rate 24 TB	Seller URL 24 TB	Price checked date 24 TB	Official compatibility source URL 24 TB	AFR source URL 24 TB

Reading a target-capacity result

Required drives is the minimum count that satisfies the selected RAID rules and allowance. Total raw capacity is drive count × capacity per drive before parity or mirroring.

Options when bays are insufficient

If the selected RAID exceeds the NAS bay limit, the result shows the missing bays and the minimum per-drive capacity needed in the available bays. It also compares other RAID levels that fit with the same drives, but do not reduce fault tolerance based on capacity alone.

Product purchase and five-year cost comparison

For each 8, 12, 16, 20, and 24 TB candidate, enter the exact model, price, CMR/SMR method, official compatibility, warranty, and AFR. Only fully checked CMR models with confirmed compatibility qualify for the 5-year expected cost ranking. Purchase review status marks missing facts for verification and excludes SMR or incompatible entries. The result keeps Empty bays and Same-RAID expansion in the same comparison.

The five-year expected cost is not a lifespan forecast. It is initial cost plus a simple expected value of initial cost × entered AFR × years after warranty. It excludes shipping, downtime, recovery, price changes, correlated failures, replacement inventory, and renewed warranty terms.

What the calculator assumes

Every drive has the same capacity. RAID 5 spends one drive-equivalent on parity, RAID 6 spends two, and RAID 10 mirrors half of the drives. Adding RAID 1 mirrors does not increase usable capacity.

RAID is not a backup. It does not protect you from deletion, ransomware, fire, theft, or failure of the entire NAS.

Mixed drives and vendor-specific RAID

Layouts such as SHR depend on drive sizes and implementation details. Recheck them with a vendor tool such as the official Synology RAID Calculator.

Compare RAID levels by fault tolerance and rebuild risk.