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.
Inputs
40 MB/s per TiB on st1, 12 MB/s per TiB on sc1.
250 MB/s per TiB on st1, 80 on sc1.
500 MB/s on st1, 250 MB/s on sc1.
st1 and sc1 meter I/O in 1 MiB units.
Sustained Baseline Throughput
240.0MB/s
Burst Throughput Ceiling
500.0MB/s
Size Needed to Sustain the Workload
7.50TiB
Implied I/O Operations per Second
300
Headroom Against the Baseline
-25.0%
Assessment
Burst only — credits drain under sustained load
Step by step
Values used
Volume size = 6 TiB; Baseline throughput per TiB = 40 MB/s per TiB; Burst throughput per TiB = 250 MB/s per TiB; Per-volume throughput ceiling = 500 MB/s; Sustained throughput the workload needs = 300 MB/s; Average I/O size = 1,024 KiB
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.
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
How it works
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
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.