What is AI cost per user?

It is your total LLM API spend divided by your active users for the same period. It tells you how much each user costs you in model inference, which is a core input to SaaS unit economics.

Why does the tool split free and paid users?

Free users still consume tokens but generate no revenue, so the real margin question is cost per paying user. The breakdown shows blended cost across everyone and the heavier cost-per-paid-user figure that hits your margin.

How is the margin impact calculated?

It divides the cost attributed to paying users by your ARPU. If AI costs eat 12% of ARPU, that is 12 points off your gross margin before any other cost of goods sold.

Should free users be counted at all?

Yes, for blended cost, because they drive total spend. But when judging viability, focus on cost per paying user since only paying users fund the bill.

Is my data sent anywhere?

No. Everything runs in your browser. Nothing you enter is uploaded, stored or logged.

AI Cost-per-User Calculator

AI cost-per-user calculator

Turn a single API invoice into real unit economics. Enter your monthly API spend, your active users, the fraction who pay, and your ARPU, and the calculator returns the blended cost per user, the sharper cost per paying user, and exactly how much of each paying user’s revenue is eaten by model inference.

How it works

Two cost figures matter:

blended_cost_per_user = api_spend / total_MAU
cost_per_paid_user    = api_spend / (total_MAU × paid_fraction)
margin_impact         = cost_per_paid_user / ARPU

The blended figure flatters you because free users dilute it. The paid figure is the honest one: it concentrates the whole bill onto the people actually paying, which is what determines whether the product makes money. Comparing cost_per_paid_user to ARPU shows the percentage of revenue lost to AI before hosting, support or payment fees.

Tips for healthy AI unit economics

Target single-digit ARPU percentage. If AI costs exceed 15–20% of ARPU, margins get thin fast once other COGS stack up.
Cap free-tier usage. Free users with no rate limits can quietly dominate spend and wreck your blended cost.
Route by tier. Serve free users a cheaper model and reserve premium models for paying tiers to protect the paid-user margin.