RAID 10 Calculator
RAID 10 (RAID 1+0) stripes data across mirrored pairs. Half the raw capacity is usable, and it gives the best random-write performance of the redundant levels.
RAID 10 at a glance
- 10 × 24TB in RAID 10 = 120TB usable (109.14 TiB), 50% of raw capacity; survives at least 1 drive failure, up to 5 if each is in a different mirrored pair.
- 100TB usable from 24TB drives in RAID 10 takes 10 drives (120TB usable).
Identical drives; decimal TB as drives are sold, binary TiB as most operating systems show it; before filesystem overhead. Hot spares are extra drives and add no capacity.
RAID 10 usable capacity by drive count
| Drives | 1.92TB | 3.84TB | 8TB | 12TB | 16TB | 24TB |
|---|---|---|---|---|---|---|
| 4 | 3.84TB | 7.68TB | 16TB | 24TB | 32TB | 48TB |
| 6 | 5.76TB | 11.52TB | 24TB | 36TB | 48TB | 72TB |
| 8 | 7.68TB | 15.36TB | 32TB | 48TB | 64TB | 96TB |
| 10 | 9.6TB | 19.2TB | 40TB | 60TB | 80TB | 120TB |
| 12 | 11.52TB | 23.04TB | 48TB | 72TB | 96TB | 144TB |
| 16 | 15.36TB | 30.72TB | 64TB | 96TB | 128TB | 192TB |
Usable capacity in decimal TB, before filesystem overhead. — means the drive count is not valid for RAID 10.
RAID 10 formula
Usable capacity = (n ÷ 2) × S. Minimum 4 drives, always an even number. Example: 8 × 1.2TB = 4.8TB (4.37 TiB).
How many failures it survives
At least one, whichever drive fails. It can survive up to one failure per mirrored pair (n ÷ 2), but if both drives of the same pair fail, the array is lost.
Write cost
Each write goes to both drives of a pair, two disk operations, with no parity to calculate. That makes RAID 10 the usual choice for databases and virtual machine storage.
24TB drives for this array
In-stock 24TB drives from our catalogue, with the price for the 10 drives in the example above. Hot spares are extra.
- Western 0F62798 Western Digital 0F62798 Ultrastar DC HC580 24TB 7200RPM 6Gb/s SATA 512e $960.00 each · 10 drives $9,600.00
- Seagate ST24000NM007H Exos X24 24TB 7200RPM 12Gb/s SAS 512MB Cache 512e 3.5-Inch Hard $1,450.00 each · 10 drives $14,500.00
- Western WUH722424ALE604 Western Digital WUH722424ALE604 Ultrastar DC HC580 24TB 7200RPM $960.00 each · 10 drives $9,600.00
- Dell GPP63 Dell 0GPP63 / GPP63 24TB 7200RPM 12Gb/s SAS 512MB Cache 512e Hot-Pluggable $1,589.47 each · 10 drives $15,894.70
- Western WD240EDGZ Western Digital WD240EDGZ 24TB 7200RPM SATA 6Gb/s 3.5-inch Internal $960.00 each · 10 drives $9,600.00
- 400-BRRZ - Dell 24TB SAS 12Gb/s 7.2K 512e 3.5-inch LFF Brand New Hard Drive for PowerEdge $1,950.00 each · 10 drives $19,500.00
- Seagate ST24000NM000H Exos X24 24TB SATA 6Gb/s 3.5-Inch Hard Drive $987.37 each · 10 drives $9,873.70
- Western 0F62835 Western Digital 0F62835 Ultrastar DC HC580 24TB 7200RPM 12Gb/s SAS 512MB $2,068.42 each · 10 drives $20,684.20
Frequently asked questions
How many 24TB drives do I need for 100TB usable in RAID 10?
10 drives in 5 mirrored pairs: 120TB usable (109.14 TiB), before filesystem overhead.
Can RAID 10 use an odd number of drives?
No. Every drive needs a mirror partner, so RAID 10 uses an even number of drives; an odd drive can serve as a hot spare.
Is RAID 10 safer than RAID 6?
Not always. RAID 6 survives any two failures; RAID 10 is only guaranteed to survive one, because two failures in the same pair lose the array.
How many drives can fail in RAID 10?
At least one. It survives one failure per mirrored pair, so up to half the drives, but not both drives of the same pair.
RAID calculators by level
- RAID calculator (all levels)
- RAID 0 calculator
- RAID 1 calculator
- RAID 5 calculator
- RAID 6 calculator
- RAID 50 calculator
- RAID 60 calculator
RAID planning guides
- How Many Drives Can Fail in Each RAID Level?
- RAID Hot Spare: What It Does and How It Affects Capacity
- TB vs TiB: Why a 24TB Drive Shows 21.8 TiB
- RAID Write Penalty by Level
- Best RAID Level for 2, 3, 4, 5, 6 or 8 Drives
- RAID 50 vs RAID 60
- RAID 6 vs RAID 60
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Updated 2026-10-22.