EBS Throughput Calculator
Size an st1 or sc1 volume from its MB/s per TiB baseline and see whether your workload lives inside it or bursts.
About EBS Throughput Calculator
st1 and sc1 buy throughput by the terabyte rather than by provisioning: baseline scales at 40 or 12 MB/s per TiB up to a per-volume ceiling, and the burst rate is only sustainable while credits last. Because both types meter I/O in 1 MiB units, small random reads waste most of each metered operation, which is why they suit sequential scans and not databases. Any workload that needs sustained throughput must be sized against the baseline, never the burst figure. Sizing to the burst number is the classic st1 mistake: the volume looks fast in a short benchmark and then falls to a fraction of that rate once the credit bucket empties during the first real batch run.
Formula
EBS Throughput
baseline = min(volume ceiling, TiB x MB/s per TiB); size needed = required MB/s ÷ MB/s per TiB; implied IOPS = MB/s x 1024 ÷ I/O size in KiB.
- MB/s per TiB
- Throughput the type earns for every TiB provisioned
- volume ceiling
- Hard per-volume throughput maximum
Worked example
With the default values below, EBS Throughput Calculator returns Sustained Baseline Throughput of 240.0. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Volume sizeminimum 0.125 TiB
- 6 TiB
- Baseline throughput per TiBminimum 0 MB/s per TiB
- 40 MB/s per TiB
- Burst throughput per TiBminimum 0 MB/s per TiB
- 250 MB/s per TiB
- Per-volume throughput ceilingminimum 1 MB/s
- 500 MB/s
- Sustained throughput the workload needsminimum 0 MB/s
- 300 MB/s
- Average I/O sizeaccepts 1–4,096 KiB
- 1,024 KiB
Results
- Sustained Baseline Throughput
- 240.0 MB/s
- Burst Throughput Ceiling
- 500.0 MB/s
- Size Needed to Sustain the Workload
- 7.50 TiB
- Implied I/O Operations per Second
- 300
- Headroom Against the Baseline
- -25.0%
- Assessment
- Burst only — credits drain under sustained load
Step by step
- 1Values used
- 2EBS Throughput
- 3Sustained Baseline Throughput= 240.0 MB/s
- 4Burst Throughput Ceiling= 500.0 MB/s
- 5Size Needed to Sustain the Workload= 7.50 TiB
- 6Implied I/O Operations per Second= 300
- 7Headroom Against the Baseline= -25.0
- 8Assessment= Burst only — credits drain under sustained load
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 or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, 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 EBS Throughput calculated?
baseline = min(volume ceiling, TiB x MB/s per TiB); size needed = required MB/s ÷ MB/s per TiB; implied IOPS = MB/s x 1024 ÷ I/O size in KiB. st1 and sc1 buy throughput by the terabyte rather than by provisioning: baseline scales at 40 or 12 MB/s per TiB up to a per-volume ceiling, and the burst rate is only sustainable while credits last. Because both types meter I/O in 1 MiB units, small random reads waste most of each metered operation, which is why they suit sequential scans and not databases. Any workload that needs sustained throughput must be sized against the baseline, never the burst figure.
Why does EBS Throughput matter?
Sizing to the burst number is the classic st1 mistake: the volume looks fast in a short benchmark and then falls to a fraction of that rate once the credit bucket empties during the first real batch run.
What values do I need to enter?
This calculator takes 6 inputs: Volume size, Baseline throughput per TiB, Burst throughput per TiB, Per-volume throughput ceiling, Sustained throughput the workload needs, Average I/O 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.
Should I use st1 for a database?
No. st1 and sc1 charge every I/O as a 1 MiB unit and have no provisionable IOPS, so random small-block access performs badly. They are built for log processing, data warehouse scans and big sequential ETL.