API Error Rate Calculator
API error rate is the portion of requests that match your chosen error definition, such as specific status codes, timeouts or application failures.
How to use this calculator
- Enter requests classified as errors, total requests observed using the same measurement window and units.
- Check the result and intermediate values, then change one input at a time when comparing scenarios.
- Keep the stated scope and assumptions attached to any result you share.
Formula and method
Error rate (%) = requests classified as errors ÷ total requests × 100.
- The observed API error rate is 0.736%.
- The metric changes if client errors, retries, cancellation or expected statuses are included. Keep the classification consistent with your service SLO.
Worked examples
Worked example
1,840 errors in 250,000 requests.
The observed API error rate is 0.736%.
The observed API error rate is 0.736%.
Understanding the result
The observed API error rate is 0.736%.
The metric changes if client errors, retries, cancellation or expected statuses are included. Keep the classification consistent with your service SLO.
Important notes
The metric changes if client errors, retries, cancellation or expected statuses are included. Keep the classification consistent with your service SLO.
Use measured inputs or documented assumptions, and validate important decisions with the appropriate source specifications or professional guidance.
Frequently asked questions
Should HTTP 4xx be errors?
That depends on the endpoint contract; separate client errors from service failures when appropriate.
Do retries count as separate requests?
Use the service metric definition and be explicit about whether attempts or logical operations are counted.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.