What sales contribute toward fixed costs and profit
Contribution is revenue remaining after variable costs and the separately entered selling fees. The ratio expresses that amount as a percentage of sales. Dividing total contribution by units gives a per-unit figure; in totals mode it is an average across the entered sales. The operating-profit result then subtracts your fixed costs.
To turn a positive unit contribution into a required sales threshold, use the Break-Even Calculator .
For a separate selling-price versus cost margin calculation, use the Profit Margin Calculator .
The formula
In unit mode, revenue equals price times whole units and variable costs equal unit cost times units. Totals mode uses the entered period amounts directly, with units required for the average per-unit result. Percentage fees are added exactly once. Negative contribution is allowed and displayed rather than rejected or replaced with zero.
A 1,000-unit sales period
Selling 1,000 units at 50 each with variable cost 30 per unit produces revenue 50,000, variable costs 30,000, and contribution 20,000. Contribution per unit is 20 and the ratio is 40%. A separate 5% selling fee reduces contribution to 17,500, per-unit contribution to 17.50, and the ratio to 35%. With fixed costs 10,000, estimated operating profit is then 7,500.
How to use this calculator
- Choose a currency and calculation basis. Enter price and variable cost per unit, or revenue and variable-cost totals.
- Enter whole units sold for the same period and any separate percentage selling fees. Add period fixed costs in advanced options if needed.
- Calculate and compare contribution, the ratio, and the income-statement breakdown. Check whether the costs include the same fee more than once.
Contribution margin differs from a profit margin
Contribution focuses on costs that change with sales or production activity. It shows what remains to cover fixed costs before any residual operating profit. A gross-profit calculation usually groups costs by their accounting classification instead. Those two cost definitions can produce different margins even when the sales revenue is identical. Choose the measure that matches the decision you are making.
Classify the costs before entering them
Packing, unit materials, per-sale platform charges, and other activity-linked costs may belong in the variable-cost amount. Period rent and other fixed overhead belong in the separate fixed-cost field. Mixed costs need an appropriate split before entering them. A percentage fee field is useful for an additional revenue-based charge, but leaving that fee in both the base cost and the fee control understates contribution.
Use totals carefully for a changing product mix
The totals basis reports a weighted average across all units sold; it does not reveal each product’s contribution. A changing mix can alter the overall ratio without any change to individual prices. For product comparisons, calculate each product separately using its own price and variable cost. For a period comparison, keep the cost definitions and time window consistent. Negative contribution indicates the included variable costs exceed revenue before fixed costs are considered.
Assumptions & limitations
What this calculation assumes
- Prices, unit costs, and percentage fees stay constant within the entered unit-mode sales period.
- Totals-mode per-unit output is an average over whole units sold.
What to keep in mind
- No product-mix optimization, capacity limits, step costs, tax calculation, inventory absorption adjustments, or complete net-income statement.
Common questions
Can contribution margin be negative?
Yes. If included variable costs and selling fees exceed revenue, each modeled sale reduces the amount available for fixed costs.
Should fixed costs reduce contribution margin?
No. Contribution is calculated before fixed costs. This tool shows a separate operating-profit estimate after subtracting the fixed costs you enter.
What if a selling fee is already in variable costs?
Leave the separate percentage fee at 0 or remove the fee from the variable-cost amount. Entering it in both places counts it twice.