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EC2 EBS Bandwidth Calculator

Find whether volume throughput, volume IOPS or the instance EBS-optimised limit caps your storage performance.

About EC2 EBS Bandwidth Calculator

Storage performance is the minimum of three independent ceilings: what the volumes can deliver in MB/s, what their IOPS budget delivers once you multiply by the average block size, and what the instance's EBS-optimised channel allows in total. Block size is the hinge — at 4 KB the IOPS limit binds long before throughput, while at 256 KB or more the throughput limit binds first. Adding volumes or provisioning more IOPS does nothing once the instance EBS-optimised limit is the binding constraint, so identifying which of the three ceilings is active tells you whether to change the volume or the instance.

Formula

EC2 EBS Bandwidth

achievable MB/s = min(volumes × volume MB/s, volumes × volume IOPS × block size, instance EBS bandwidth).

block size
Average I/O size in MB, used to convert IOPS to MB/s
aggregate
Sum across all attached volumes
instance limit
EBS-optimised ceiling shared by every volume on the instance

Worked example

With the default values below, EC2 EBS Bandwidth Calculator returns Achievable Throughput of 188. Change any input above and every figure here is recalculated in your browser.

Inputs used

Instance EBS bandwidth limitaccepts 1–20,000 MB/s
593 MB/s
Instance EBS IOPS limitaccepts 1–1,000,000 IOPS
18,750 IOPS
Volumes attachedaccepts 1–40 volumes
4 volumes
Throughput provisioned per volumeaccepts 1–4,000 MB/s
250 MB/s
IOPS provisioned per volumeaccepts 1–256,000 IOPS
3,000 IOPS
Average I/O block sizeaccepts 1–1,024 KB
16 KB

Results

Achievable Throughput
188 MB/s
Achievable IOPS
12,000
Aggregate Volume Throughput
1,000 MB/s
Throughput Implied by the IOPS Limit
188 MB/s
Unused Instance Bandwidth
406 MB/s
Binding Limit
Volume IOPS at this block size

Step by step

  1. 1Values used
  2. 2EC2 EBS Bandwidth
  3. 3Achievable Throughput= 188 MB/s
  4. 4Achievable IOPS= 12,000
  5. 5Aggregate Volume Throughput= 1,000 MB/s
  6. 6Throughput Implied by the IOPS Limit= 188 MB/s
  7. 7Unused Instance Bandwidth= 406 MB/s
  8. 8Binding Limit= Volume IOPS at this block size

Assumptions and limits

  • The result is derived only from the 6 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is EC2 EBS Bandwidth calculated?

achievable MB/s = min(volumes × volume MB/s, volumes × volume IOPS × block size, instance EBS bandwidth). Storage performance is the minimum of three independent ceilings: what the volumes can deliver in MB/s, what their IOPS budget delivers once you multiply by the average block size, and what the instance's EBS-optimised channel allows in total. Block size is the hinge — at 4 KB the IOPS limit binds long before throughput, while at 256 KB or more the throughput limit binds first.

Why does EC2 EBS Bandwidth matter?

Adding volumes or provisioning more IOPS does nothing once the instance EBS-optimised limit is the binding constraint, so identifying which of the three ceilings is active tells you whether to change the volume or the instance.

What values do I need to enter?

This calculator takes 6 inputs: Instance EBS bandwidth limit, Instance EBS IOPS limit, Volumes attached, Throughput provisioned per volume, IOPS provisioned per volume, Average I/O block size. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

Why does my 16 KB workload not hit the volume's rated MB/s?

Because the IOPS budget caps you first. Four gp3 volumes at 3000 IOPS give 12,000 IOPS, which at 16 KB is only about 188 MB/s regardless of the 250 MB/s each volume is rated for. Larger I/O sizes, or more provisioned IOPS, are the only ways up.

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