A/B Testing API Cost (Monthly) Calculator
Estimate the monthly API cost of running an A/B test based on traffic, test allocation, API calls per visitor, and your provider's pricing.
Overview
Estimate the monthly API cost of an A/B test by combining average daily traffic, the percentage of traffic in the test, API calls per test visitor, and your API provider's price per million calls.
How it works
The calculator first applies your test traffic percentage to daily visitors. It multiplies that result by the days in the billing month to estimate test visitors, then multiplies by API calls per visitor to calculate monthly API calls. Finally, it divides calls by one million and applies your stated price per million calls. This helps isolate variable API usage costs associated with a particular experiment.
How to use this calculator
- 1Enter the average number of visitors evaluated each day.
- 2Set the percentage of traffic included in the experiment.
- 3Estimate all API calls generated by each test visitor.
- 4Enter your provider's cost per one million API calls.
- 5Choose the number of days in the billing month and review the estimated cost.
Example Calculation
Average daily visitors
10000
Traffic included in test
100%
API calls per test visitor
2
API cost per million calls
$5
Days in billing month
30
Estimated monthly API cost
$3.00
With 10,000 daily visitors, full test traffic, two calls per visitor, and a price of 5 per million calls, the test generates about 600,000 calls and costs about 3.00 for a 30-day month.
Frequently asked questions
What counts as an API call in an A/B test?
It depends on your setup. Common calls include experiment assignment, feature-flag evaluation, configuration retrieval, exposure logging, and conversion-event tracking.
Should I include traffic not enrolled in the experiment?
Only include it if those visitors still trigger billable experiment or feature-flag API calls. Otherwise, use the percentage of traffic actually evaluated by the test.
How do I estimate API calls per visitor?
Review a typical user journey and count expected billable calls. Include repeated page views, sessions, events, and server-side evaluations where relevant.
Does the calculator include subscription fees or free quotas?
No. It estimates variable usage charges from your stated price per million calls. Add any fixed plan fee separately and account for included usage before relying on the estimate.
Why might my actual API bill be different?
Actual usage can change with traffic patterns, bots, retries, caching, multiple devices, event volume, provider rounding, tiered pricing, and billing-period differences.
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Assumptions and warnings
Assumptions
- Traffic is spread evenly across the selected number of billing days.
- Each test visitor generates the average number of API calls entered.
- The price per million calls is constant for all usage in the month.
- The estimate includes variable API usage charges only, not platform subscriptions, implementation work, or taxes.
- Results are estimates and may differ from your provider's final usage records and billing rules.
Warnings
- This calculator provides a usage-cost estimate only and is not financial advice.
- Check your provider's pricing for included quotas, tiered rates, minimum charges, overages, and applicable taxes.