THE NUMBERS, EXPLAINED
How to use this calculator.
Retry i uses min(cap, initial × multiplier^(i−1)). Optional full jitter chooses whole milliseconds from zero through one less than the capped whole-millisecond bound using a reproducible Park–Miller sequence. Timings exclude request execution. This educational seed is not cryptographic randomness.
Start with your inputs
Enter initial retry delay (ms), backoff multiplier, delay cap (ms), retries after the initial attempt, no jitter (0) or seeded full jitter (1), seed (1–2147483646). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Initial retry delay (ms) | 100 |
| Backoff multiplier | 2 |
| Delay cap (ms) | 500 |
| Retries after the initial attempt | 4 |
| No jitter (0) or seeded full jitter (1) | 0 |
| Seed (1–2147483646) | 1 |
A worked example
With the example inputs above, retry waits (ms) is 100, 200, 400, 500. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Retry waits (ms) | 100, 200, 400, 500 |
| Retry times after initial attempt (ms) | 100, 300, 700, 1200 |
| Total waiting (ms) | 1,200 |
How this is calculated
Retry waits (ms)
Generate capped exponential delays. With full jitter, advance seed = seed × 16807 mod 2147483647 and take floor(floor(delay) × seed / 2147483647).
Retry times after initial attempt (ms)
Cumulative sum of waits, measured from the initial attempt; listed times round to six decimals.
Total waiting (ms)
Sum the unrounded waits; no execution or response time is included.
Symbols and units
- a
- Initial retry delay (ms)
- b
- Backoff multiplier
- c
- Delay cap (ms)
- d
- Retries after the initial attempt
- e
- No jitter (0) or seeded full jitter (1)
- f
- Seed (1–2147483646)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions and limits
Retry i uses min(cap, initial × multiplier^(i−1)). Optional full jitter chooses whole milliseconds from zero through one less than the capped whole-millisecond bound using a reproducible Park–Miller sequence. Timings exclude request execution. This educational seed is not cryptographic randomness.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Retry waits (ms); Retry times after initial attempt (ms); Total waiting (ms). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Retry i uses min(cap, initial × multiplier^(i−1)). Optional full jitter chooses whole milliseconds from zero through one less than the capped whole-millisecond bound using a reproducible Park–Miller sequence. Timings exclude request execution. This educational seed is not cryptographic randomness.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Further reading
AWS: retry and backoff assumptions ↗
Background reading; this does not imply endorsement or independent review of SumFizz.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →