Why round the price for a target margin up, not to the nearest cent?

Nearest can fall just below the target margin

Which data do you need to compute margin per customer?

Cost records with a customer id, joined with billing

Pricing an AI Feature

By Syncfusion®, Inc. · Last updated November 2, 2026

Turn cost records into unit economics in TypeScript or C#: margin per seat, break-even usage, the price for a target margin, and an allowance plan that makes money on every seat.

What you will learn

Compute cost, revenue and margin per seat and for a whole plan
Find the break-even usage of a seat
Find the lowest price that reaches a target margin
Design and check a plan with an allowance and overage

Price the Feature From Your Own Records

Brightgrid sells its AI assistant as an add-on: $5 per agent seat per month.

In Where the Money and the Milliseconds Go, your meter measured one ticket: about $0.0034 in model calls. Search, logs and storage add about $0.0006. So one AI-handled ticket costs about $0.0040.

That looks tiny. But a seat that handles 5,200 tickets a month costs almost $21, and pays $5.

In this lesson, you will turn your cost records into unit economics in code. Then you will design a plan that makes money on every seat.

Press Play, or use Next to go one step at a time.

Each row: one seat, its tickets this month, what it pays and what it costs.
Red rows: seats that lose money.
The last frame: the same seats on a plan with an allowance.

Simple lesson: a flat price on a usage-based cost loses money on your heaviest users.

A Real-World Example

The billing export shows 12 seats last month. Five of them used more than 1,241 AI tickets.

The finance team saw "AI add-on: $60 revenue". They did not see the $74.59 in model and search costs, because those sit in a different bill.

Simple lesson: put revenue and model cost in the same report, per customer.

What You Will Build

In this lesson, you will learn:

how to compute cost, revenue and margin per seat and for the whole plan
how to find the break-even usage of a seat
how to find the lowest price that reaches a target margin
how to design a plan with an allowance and overage, and check it in code

You will finish three files in the pricing folder of the project.

Seat economics (src/pricing/seatEconomics.ts, or Pricing/SeatEconomics.cs): margin per seat and per plan.
Break-even (src/pricing/breakEven.ts, or Pricing/BreakEven.cs): break-even tickets and the price for a margin.
Plan design (src/pricing/planDesign.ts, or Pricing/PlanDesign.cs): bills with an allowance, and a plan check.

Open the Code tab.

The harness file: the 12 seats from billing, the cost per ticket and today's price.
The cost per ticket: your Lesson 2 number plus the non-model costs.

For product managers: this lesson is your main lesson. You can run every cell without changing code. Change the numbers in the cells to try your own prices.

Simple lesson: unit economics are code, so they can run on every month's real data.

Margin per Seat

For one seat in one month:

Cost = tickets × cost per ticket.
Revenue = what the seat pays.
Margin = revenue minus cost.

For the plan, add up revenue and cost across seats. Margin % = margin ÷ revenue.

Run the cell. Read the margin column from top to bottom.

Light seats: almost all of the $5 is margin.
Heavy seats: the margin goes negative and keeps falling.
The last line: the whole plan loses money.

Simple lesson: look at the distribution of usage, not the average.

Break-Even and Price for a Margin

Two numbers answer most pricing questions.

Break-Even Usage

Break-even tickets = price ÷ cost per ticket, rounded down.

At $5 and about $0.0040 a ticket, a seat breaks even at 1,241 tickets. Every ticket after that loses money.

Price for a Target Margin

Software teams often aim for a gross margin such as 60% or more. Solve the margin formula for the price:

price = total cost ÷ (seats × (1 − target margin))

Round up to whole cents. Rounding to the nearest cent can land just below the target.

The cost per ticket changes. Every lever in this course lowers it, and a new model or a price change can raise it. Recompute these numbers from your cost records every month, not once at launch.

Simple lesson: know the usage where a customer stops paying for themselves.

Design a Plan That Covers Heavy Users

A flat price that covers the heaviest seat is too expensive for everyone else. At about $16 a seat the plan reaches 60%, and the 5,200-ticket seat still loses money.

A common fix is an allowance:

the price includes a number of AI tickets
each started block of 1,000 extra tickets costs a fixed amount

Run the cell. Then add your own plan to the list.

Flat $5: five seats lose money.
Flat $16: good margin, but one seat still loses money, and light users pay three times more.
$5 + 1,000 included + $6 per started 1,000: no seat loses money.

Test the plan on real usage, not on a typical customer. A plan that works for the average seat can still lose money on the top 10%. Run the plan check on last month's billing data before you change prices.

Run npm run economics (or dotnet run -- economics) in the Code tab. It prints today's margin, the break-even, the price for 60% and the allowance plan.

Simple lesson: charge for usage above a fair allowance, and prove it on real data.

Try it on a real model. Guessed costs make weak plans. Run three real tickets, and get a cost per seat from measured tokens. Switch Model to Real in the lab's top bar. It runs an open model in your browser with WebLLM, and needs WebGPU. It is not graded.

Put It in Your App

Join the data. Group your cost records by customer or seat id, and join them with billing. Pass that id in every CallMeta.
Run the check monthly. A scheduled job can run checkPlan on last month's data and post the result.
Show usage to customers. If a plan has an allowance, show how much is left. Surprise overage bills create support tickets.

Keep pricing logic out of the request path. The meter logs costs. A separate job turns them into bills and reports. Then a pricing change never slows down a user's request.

Simple lesson: cost records plus billing data give you margin per customer.

Common mistakes

Mistake	Wrong idea	Correct idea	What goes wrong
Pricing from the average user	"Most users are light."	Check the whole distribution.	The heaviest users wipe out the margin.
Counting only model calls	"The LLM bill is the cost."	Add search, storage and logging per action.	Margin looks higher than it is.
Rounding the price to the nearest cent	"A cent does not matter."	Round up for a target margin.	The margin lands just below the target.
Floor instead of ceiling for overage blocks	"1,200 extra is one block, 200 is zero."	Charge each started block.	Usage just over the allowance is free.
Setting the price once	"Costs are stable."	Recompute monthly from records.	A model change silently erodes margin.

Check Your Understanding

Exercises

Build It in the Project

The other files of this lesson's project are optional practice. Finish them to run the lesson's script on your own code.

What to Remember

Cost per action comes from your cost records, plus non-model costs.
A flat price on usage-based cost loses money on heavy users.
Break-even usage = price ÷ cost per action, rounded down.
Price for a margin = cost ÷ (seats × (1 − margin)), rounded up.
An allowance plus overage keeps light users cheap and heavy users profitable.
Recompute these numbers every month.

Next: How LLM Latency Works. You will split a slow answer into network, queue, prefill and decode, and give each step a budget.