Break-Even, Pricing and Contribution Margin Lab

'What price do I need?' is usually answered with a guess or a one-product calculator. Real businesses sell a mix, carry card fees and commissions as a percentage of price, and know that a higher price loses some volume. This lab shows break-even at your actual mix and solves for the price change that reaches your profit target.

What is inside

• Inputs: target profit, an elasticity estimate, capacity, and per-product price, discount, variable cost, variable percentage (card fees, commission) and monthly units, plus up to 15 fixed costs.
• Mix: contribution per unit, weighted contribution, break-even units and revenue at your mix, margin of safety and the product-level split.
• Pricing: the uniform price change that reaches the target. With a volume response the profit becomes a quadratic in the price change, which the sheet solves with the quadratic formula. Section 3 gives the price per product.
• Sensitivity: profit under price and volume moves, and break-even under price and fixed-cost moves.
• Dashboard with three native charts, and Checks.

How it is deeper than the cheaper Startup Costs and Break-even Planner and the Pricing and Margin Calculator Suite: they work one product at a time. This lab works on a sales mix and models the volume response to price instead of holding volume fixed.

Facts and settings: elasticity is your estimate and is the same for every product. Fixed costs are held constant at every volume, so add a step cost if you pass capacity. Taxes are not modelled and prices are excluding VAT.

What it is NOT: it is a calculation tool, not accounting, tax or legal advice. It is not connected to your bank or accounting system, it is not an FTA-approved system and it is not an e-invoicing tool (e-invoicing is on the Zeyto roadmap only). Where a rule matters it is a setting you enter, with a note to confirm it with the FTA, your accountant or your auditor.

Two workbooks: an EXAMPLE copy filled with invented data so you can see every sheet working, and a BLANK copy with the same formulas ready for your own data. Formulas only: no macros, no volatile functions, no add-ins. Input cells are coloured, formula sheets are protected without a password, and a Checks sheet turns green only when every list ties out.

How it was checked: recalculated with an independent Python formula engine and 248 outputs (contribution, break-even, margin of safety, required price change, per-product prices, sensitivity grids and chart series) were compared with a separate Python model, with no difference. There is no Excel or LibreOffice on the build machine, so it was not opened in them and the charts were not viewed on screen.

Limits: the mix is held fixed, one elasticity for all products, and results are a guide for discussion, not a forecast.