Cache Memory Calculator
Model the effective latency a cache delivers and the memory it needs.
About Cache Memory Calculator
Effective latency is dominated by misses once the hit rate is high, because the origin path is orders of magnitude slower. Raising a hit rate from 88 to 95 per cent nearly halves effective latency. This is why the last few percentage points of hit rate are worth pursuing even though they require disproportionate memory.
Formula
Cache Memory
Effective latency = cache latency × hit rate + origin latency × miss rate
- effective latency
- Weighted average across hits and misses
Worked example
With the default values below, Cache Memory Calculator returns Effective Latency of 5.7520. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Entries held in cacheminimum 0
- 500,000
- Bytes per entryminimum 0 bytes
- 2,400 bytes
- Hit rateaccepts 0–100 %
- 88 %
- Cache latencyminimum 0 ms
- 0.4 ms
- Origin latencyminimum 0 ms
- 45 ms
Results
- Effective Latency
- 5.7520 ms
- Cache Memory Required
- 1.1176 GB
- Latency Saved per Request
- 39.2480 ms
- Speed Improvement
- 7.823 x
- Reduction in Origin Load
- 88.00%
Step by step
- 1Values used
- 2Cache Memory
- 3Effective Latency= 5.7520 ms
- 4Cache Memory Required= 1.1176 GB
- 5Latency Saved per Request= 39.2480 ms
- 6Speed Improvement= 7.823 x
- 7Reduction in Origin Load= 88.00
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 4 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 Cache Memory calculated?
Effective latency = cache latency × hit rate + origin latency × miss rate Effective latency is dominated by misses once the hit rate is high, because the origin path is orders of magnitude slower. Raising a hit rate from 88 to 95 per cent nearly halves effective latency.
Why does Cache Memory matter?
This is why the last few percentage points of hit rate are worth pursuing even though they require disproportionate memory.
What values do I need to enter?
This calculator takes 5 inputs: Entries held in cache, Bytes per entry, Hit rate, Cache latency, Origin latency. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.