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Server Request Rate

Free Server Request Rate calculator with clear step-by-step results.

About Server Request Rate

Average request rate is total requests divided by the seconds in the period, but capacity is never sized on the average. Real traffic is peaky, and a peak-to-average ratio of 2-4 is common for consumer-facing services with a daily cycle. Little's law then converts the peak rate into concurrency: requests in flight = arrival rate × average time in the system, which is the number that determines how many workers, connections or threads you need.

Formulas

Request rate

Requests per second = total requests ÷ (period hours × 3600)

Concurrency (Little's law)

Concurrent requests = peak rate × average response time

Worked example

With the default values below, Server Request Rate returns Average Request Rate of 100.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total requests in the periodminimum 0
8,640,000
Length of the periodminimum 0.01 h
24 h
Peak to average ratiominimum 1
3
Average response timeminimum 0.001 s
0.25 s

Results

Average Request Rate
100.00 req/s
Average Request Rate
6,000.0 req/min
Peak Request Rate
300.00 req/s
Concurrent Requests in Flight at Peak
75.00

Step by step

  1. 1Values used
  2. 2Request rate
  3. 3Concurrency (Little's law)
  4. 4Average Request Rate= 100.00 req/s
  5. 5Average Request Rate= 6,000.0 req/min
  6. 6Peak Request Rate= 300.00 req/s
  7. 7Concurrent Requests in Flight at Peak= 75.00

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges 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.
  • Traffic modelled as a flat average with a peak multiplier is a planning approximation. Size production capacity against measured percentiles and load-test results.

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

Traffic modelled as a flat average with a peak multiplier is a planning approximation. Size production capacity against measured percentiles and load-test results.

Frequently Asked Questions

Why does concurrency matter more than rate?

Because pools are sized in slots, not in requests per second. At 100 req/s with a 250 ms response you need about 25 concurrent slots; the same rate with a 2-second response needs 200, and the pool exhausts long before CPU does.

What peak-to-average ratio should I use?

Measure it if you can. Where you cannot, 2-3 is typical for a service with a single daily peak, 5-10 for event-driven or campaign-driven traffic, and higher still for anything triggered by a scheduled job or a broadcast.

Does this account for retries?

No — include them in the total request count. Retry storms are a common cause of the peak ratio being far worse than expected, since failures generate additional load precisely when the system is struggling.

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