Worked example
A 200 GiB Standard SSD in East US, with 50 GiB used:
- Priced as: E15, a 256 GiB tier, at $19.20 a month.
- Empty space: 200 − 50 = 150 GiB, or 75% of the disk.
- Cost of the empty space: $19.20 × 150 ÷ 256 = $11.25 a month.
- Tier space above the disk: 256 − 200 = 56 GiB, or $4.20 a month.
A 200 GiB gp3 volume in US East (N. Virginia), with 50 GiB used:
- Monthly cost: $0.08 per GB-month × 200 = $16.00.
- Empty space: 150 GiB, or 75% of the volume.
- Cost of the empty space: $0.08 × 150 = $12.00 a month.
How the calculator works
The disk’s monthly cost
- Azure: Azure rounds a managed disk’s size up to the nearest tier, and prices the tier. In Microsoft’s own example, a 200 GiB Standard SSD is priced as E15, a 256 GiB tier.
- AWS: AWS prices EBS storage per GB you provision, per month. On AWS’s EBS pricing page a GB is 1024³ bytes, so it equals a GiB.
- The price: the list price in USD. On Azure it’s pay-as-you-go, LRS. On AWS it’s on-demand. Both are before any discount, reservation or negotiated rate.
- Storage only: transactions, bursting and snapshots aren’t counted.
- gp3: its price includes a baseline of 3,000 IOPS and 125 MiB/s. The calculator assumes your volume uses that baseline. Extra IOPS or throughput aren’t counted.
Empty space and what it costs
- Empty space = the disk size − the used space, and never below 0.
- Its share = the empty space ÷ the disk size.
- On Azure, the empty space costs the tier’s monthly price × the empty GiB ÷ the tier’s GiB.
- On AWS, it costs the price per GB-month × the empty GiB.
On Azure the tier can be larger than the disk. That extra space gets its own line, apart from the empty space.
Why empty space stays
An Azure managed disk and an EBS volume can grow, but neither can be made smaller in place. Microsoft’s guides to expanding a disk on Linux (opens in a new tab) and Windows (opens in a new tab) VMs say shrinking an existing disk isn’t supported. AWS’s guide to modifying an EBS volume (opens in a new tab) says you can’t decrease its size.
So once a disk grows, you pay for its full size from then on, however much data it holds.
Sources
Prices from the Azure Retail Prices API (opens in a new tab) and the AWS Price List for Amazon EC2 (opens in a new tab), which carries EBS, retrieved 30 October 2026. Tier sizes and the round-up rule from Microsoft Learn’s Azure managed disk types (opens in a new tab). EBS terms from Amazon EBS pricing (opens in a new tab) and AWS’s General Purpose SSD volumes (opens in a new tab), checked 30 October 2026. Prices change; check your cloud’s price list before you buy.
List prices, 30 October 2026
Azure Premium SSD (LRS): monthly list price per disk
| Tier | Size | East US | West Europe | Central India |
|---|---|---|---|---|
P1 | 4 GiB | $0.60 | $0.78 | $0.84 |
P2 | 8 GiB | $1.20 | $1.56 | $1.68 |
P3 | 16 GiB | $2.40 | $3.12 | $3.36 |
P4 | 32 GiB | $5.28 | $5.81 | $5.28 |
P6 | 64 GiB | $10.21 | $11.23 | $10.21 |
P10 | 128 GiB | $19.71 | $21.68 | $19.71 |
P15 | 256 GiB | $38.01 | $41.81 | $38.01 |
P20 | 512 GiB | $73.22 | $80.54 | $73.22 |
P30 | 1,024 GiB | $135.17 | $148.68 | $135.17 |
P40 | 2,048 GiB | $259.05 | $284.94 | $259.05 |
P50 | 4,096 GiB | $495.57 | $545.10 | $495.57 |
P60 | 8,192 GiB | $946.08 | $1,040.64 | $946.08 |
P70 | 16,384 GiB | $1,802.06 | $1,982.17 | $1,802.06 |
P80 | 32,767 GiB | $3,604.11 | $3,964.34 | $3,604.11 |
Azure Standard SSD (LRS): monthly list price per disk
| Tier | Size | East US | West Europe | Central India |
|---|---|---|---|---|
E1 | 4 GiB | $0.30 | $0.30 | $0.33 |
E2 | 8 GiB | $0.60 | $0.60 | $0.66 |
E3 | 16 GiB | $1.20 | $1.20 | $1.32 |
E4 | 32 GiB | $2.40 | $2.40 | $2.64 |
E6 | 64 GiB | $4.80 | $4.80 | $5.28 |
E10 | 128 GiB | $9.60 | $9.60 | $10.56 |
E15 | 256 GiB | $19.20 | $19.20 | $21.12 |
E20 | 512 GiB | $38.40 | $38.40 | $42.24 |
E30 | 1,024 GiB | $76.80 | $76.80 | $84.48 |
E40 | 2,048 GiB | $153.60 | $153.60 | $168.96 |
E50 | 4,096 GiB | $307.20 | $307.20 | $337.92 |
E60 | 8,192 GiB | $614.40 | $614.40 | $675.84 |
E70 | 16,384 GiB | $1,228.80 | $1,228.80 | $1,351.68 |
E80 | 32,767 GiB | $2,457.60 | $2,457.60 | $2,703.36 |
Amazon EBS: storage list price per GB-month
| Volume type | US East (N. Virginia) | EU (Ireland) | Asia Pacific (Mumbai) |
|---|---|---|---|
gp3 | $0.08 | $0.088 | $0.0912 |
gp2 | $0.10 | $0.11 | $0.114 |