AI Cost Per User Calculator
Turn raw model token prices into the numbers that decide the business: your LLM cost per active user, the break-even subscription price, and the gross margin at any price you set — across Claude, GPT, and Gemini, in dollars and rupees. No signup, sources cited.
How it works
A monthly API-bill calculator answers “what will I spend?” This one answers the question a founder actually loses sleep over: at my price, do I make money on each user, and which model keeps me in the black? It works from the same vendor token prices — input and output are priced separately per 1,000,000 tokens, with output almost always more expensive because the model spends compute generating each token.
Let inP and outPbe the model's input and output price per 1M tokens. The calculation runs in five steps:
- Effective input price after caching. A cached share of the input is billed at about 10% of the input price, so
effInP = inP × (1 − cachedShare × 0.90), with cachedShare between 0 and 1. - Cost per request.
costReq = (inputTokens / 1e6) × effInP + (outputTokens / 1e6) × outP. - Cost per user per month.
costUser = costReq × requestsPerUser. This is the headline figure. Total monthly cost iscostUser × MAU, and the annual figure is twelve times that. - Break-even price.
breakEven = costUser— the subscription price where revenue equals the LLM cost. Payment-processor fees push the real break-even slightly higher; that is out of scope for v1 and noted in the tool. - Gross margin. At your price P,
margin = (P − costUser) / P. A negative result means the model bill exceeds your price — a per-user loss, rendered in red. Rupee figures multiply the dollar cost by an editable CBSL indicative exchange rate.
Every figure is cross-checked: the per-1,000,000-token math is re-derived through an independent per-1,000-token path and the two must agree to the cent, the same credibility check the site's tax calculator runs against the IRD formula. Token prices are the shared vendor pricing table (Claude, GPT, Gemini), last verified 2026-06-30; the formulas were reconciled 2026-07-08.
Worked examples
Each example works the math by hand. All three are encoded in the tool's self-test and reconcile to the figures shown, at Rs 300 per US dollar.
Frequently asked questions
Sources & references
- Anthropic — Claude API pricing (per-million-token input/output rates)
- OpenAI — API pricing (GPT models)
- Google — Gemini API pricing
- Central Bank of Sri Lanka — daily indicative USD→LKR exchange rates
Token prices are transcribed from the vendor pricing pages above and last verified on 2026-06-30; the formulas and worked examples were reconciled on 2026-07-08. Prices move often, so re-check the live pages before committing a budget. The tool runs entirely in your browser — no inputs leave your device.
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Comments & feedback
Spotted a bug or want an improvement? Tell us — our team reviews every comment, and good ideas get built. Comments are public and anonymous.
Found a bug, a pricing change, or want another provider added?
Email me at [email protected] — most fixes ship within 24 hours.