Database IOPS Calculator
Calculate the IOPS a workload requires including read and write amplification.
About Database IOPS Calculator
The buffer cache absorbs most reads, so only misses reach storage. Writes amplify instead, because each one touches every index and the write-ahead log. Under-provisioning IOPS causes latency to collapse non-linearly once the queue saturates, which is why headroom matters more here than for throughput.
Formula
Database IOPS
IOPS = reads × miss rate + writes × (1 + indexes) × 2, plus headroom
- write amplification
- Each write also updates indexes and the write-ahead log
- buffer cache
- Absorbs most reads, so misses rather than reads drive storage IOPS
Worked example
With the default values below, Database IOPS Calculator returns IOPS to Provision of 10,816. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Reads per secondminimum 0
- 4,000
- Writes per secondminimum 0
- 800
- Buffer cache hit rateaccepts 0–100 %
- 92 %
- Indexes updated per writeminimum 0
- 4
- Headroom for peaksaccepts 0–100 %
- 30 %
Results
- IOPS to Provision
- 10,816
- Read IOPS Reaching Storage
- 320
- Write IOPS Reaching Storage
- 8,000
- Total IOPS Before Headroom
- 8,320
- Read IOPS Absorbed by Cache
- 3,680
Step by step
- 1Values used
- 2Database IOPS
- 3IOPS to Provision= 10,816
- 4Read IOPS Reaching Storage= 320
- 5Write IOPS Reaching Storage= 8,000
- 6Total IOPS Before Headroom= 8,320
- 7Read IOPS Absorbed by Cache= 3,680
Assumptions and limits
- The result is derived only from the 5 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 Database IOPS calculated?
IOPS = reads × miss rate + writes × (1 + indexes) × 2, plus headroom The buffer cache absorbs most reads, so only misses reach storage. Writes amplify instead, because each one touches every index and the write-ahead log.
Why does Database IOPS matter?
Under-provisioning IOPS causes latency to collapse non-linearly once the queue saturates, which is why headroom matters more here than for throughput.
What values do I need to enter?
This calculator takes 5 inputs: Reads per second, Writes per second, Buffer cache hit rate, Indexes updated per write, Headroom for peaks. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.