A/B Testing Token Usage Formula
Learn how annual AI token usage and estimated token cost are calculated for an A/B testing program.
This formula estimates the annual AI token demand created by planned A/B tests. It turns eligible traffic, test allocation, test volume, request frequency, and average tokens per request into a budget estimate, then applies your entered price per million tokens.
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Annual Token Usage
Where:
Annualize the eligible audience, take the share included in each test, count every planned test exposure, then multiply by AI requests and average tokens used for each request.
Variables Explained
| Variable | What It Means | Unit |
|---|---|---|
| monthlyVisitors - Monthly eligible visitors | Average monthly visitors or users who could be included in an individual test. | number |
| testTrafficPercent - Traffic allocated to each test | Percentage of annual eligible traffic included in one A/B test. | percent |
| testsPerYear - A/B tests per year | Number of separate AI-powered tests planned during the year. | number |
| requestsPerParticipant - AI requests per participant | Average token-consuming AI or API requests made by a participant in one test. | number |
| tokensPerRequest - Average tokens per request | Combined average input and output tokens consumed by one AI request. | tokens |
| pricePerMillionTokens - Price per 1 million tokens | Blended expected price for one million tokens in the selected currency. | currency |
| variantsPerTest - Variants per test | Total variants, including the control, used to allocate the total estimate evenly for the per-variant output. | number |
Step-by-Step Calculation
Annualize eligible traffic
Convert the average eligible monthly audience into an annual audience estimate.
annualEligibleVisitors = monthlyVisitors * 12
Calculate participants in one test
Apply the traffic share assigned to an individual test.
participantsPerTest = annualEligibleVisitors * (testTrafficPercent / 100)
Count annual participant exposures
Multiply participants in one test by the number of planned tests. A person exposed to separate tests can be counted more than once.
annualTestParticipants = participantsPerTest * testsPerYear
Estimate annual AI requests
Each participant exposure is multiplied by the average number of AI requests it generates.
annualRequests = annualTestParticipants * requestsPerParticipant
Calculate annual token usage
Multiply total requests by the combined average input and output tokens per request.
annualTokenUsage = annualRequests * tokensPerRequest
Estimate cost and per-variant usage
Price is based on millions of tokens. The per-variant figure divides total usage evenly and does not change total usage by itself.
annualTokenCost = (annualTokenUsage / 1000000) * pricePerMillionTokens; tokensPerVariant = annualTokenUsage / variantsPerTest
Example: Four AI-powered A/B tests in a year
Annual eligible visitors
100,000 × 12
1,200,000 visitors
Participants per test
1,200,000 × 20 / 100
240,000 participants
Annual participant exposures
240,000 × 4
960,000 exposures
Annual AI requests
960,000 × 3
2,880,000 requests
Annual token usage
2,880,000 × 1,500
4,320,000,000 tokens
Estimated annual token cost
4,320,000,000 / 1,000,000 × $5.00
$21,600.00
Final Result
Estimated annual usage is 4.32 billion tokens, costing approximately $21,600.00. With an even two-variant split, the average is 2.16 billion tokens per variant.
Assumptions
- ✓Eligible monthly traffic remains broadly consistent across the year.
- ✓The stated traffic allocation is applied separately to every planned test.
- ✓Each participant exposure produces the entered average number of AI requests.
- ✓Average tokens per request include both input and output tokens.
- ✓The entered price per million tokens is an appropriate blended price for the expected workload.
- ✓Variant traffic is split evenly when calculating the average tokens per variant.
Limitations
- !Actual traffic can be seasonal and may differ materially from the monthly average.
- !Prompt length, output length, model selection, retries, tool calls, and errors can change token usage.
- !The estimate counts separate test exposures, so it does not deduplicate users who appear in multiple tests.
- !Token prices, volume discounts, cached-token treatment, and provider charges may change over time.
- !The even per-variant calculation may not reflect uneven allocation or variant-specific request behavior.
Common Mistakes to Avoid
Entering input tokens but excluding output tokens from the average tokens per request.
Using total site traffic instead of the traffic that is genuinely eligible for the test.
Treating the test allocation as a share across all annual tests rather than the allocation for each individual test.
Assuming that adding variants automatically increases total tokens when the same total test traffic is simply split more ways.
Forgetting repeated requests, retries, fallback model calls, or multi-step AI interactions.
Using a list price that does not match the model mix or pricing basis expected in production.
Related Formulas
Frequently Asked Questions
What is the annual A/B testing token usage formula?
Annual token usage equals monthly eligible visitors × 12 × test traffic percentage × tests per year × requests per participant × tokens per request.
How is annual A/B testing token cost calculated?
Divide estimated annual token usage by 1,000,000 and multiply the result by your entered price per million tokens.
Why are visitors multiplied by 12?
The calculator starts with an average monthly eligible audience, so multiplying by 12 creates an annual traffic estimate.
Do two variants double token usage?
Not necessarily. When the same total test traffic is divided between two variants, total requests and total tokens can remain the same. The calculator uses variants to show an even-split per-variant estimate.
Should tokens per request include prompts and responses?
Yes. Use a combined average of input tokens and output tokens for each AI request.
Why can annual participant exposures exceed annual visitors?
The estimate treats each test as a separate exposure. A visitor who participates in more than one planned test may be included more than once.
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