Contribution Margin Calculator

What Is the Contribution Margin Calculator?

Contribution margin is how much each unit sold "contributes" toward covering fixed costs, after variable costs are subtracted -- the key input to break-even analysis.

How to Use This Tool

Enter price per unit and variable cost per unit. Contribution margin and its ratio appear instantly.

The Formula

A Worked Example

With the default inputs, price per unit is 50 and variable cost per unit is 20. Contribution margin is 30 per unit, and the ratio is 30 divided by 50, or 60 percent. The tool shows the ratio as a percentage. In plain terms, every sale brings in 50, uses 20 on costs that only exist because the sale happened, and leaves 30 to pay for fixed costs and then profit.

Now suppose a hypothetical online course seller has 6,000 of fixed costs each month. At 30 contribution per sale, the seller needs 200 sales to cover those costs. Sale number 201 adds 30 of profit. If a second course sells for 80 with variable cost of 32, its contribution is 48 and its ratio is 60 percent as well, even though the money per sale is higher.

Contribution Margin Versus Gross Margin

The two are similar but not the same. Gross margin subtracts cost of goods sold, which may include some fixed production costs such as factory rent or salaried supervisors. Contribution margin subtracts only costs that truly rise and fall with each unit sold, for example materials, sales commissions, shipping and payment processing fees. Contribution margin is therefore the better guide for decisions about volume, pricing and whether to accept a special order, because it isolates what changes when sales change.

What to Include in Variable Cost

• Materials or the purchase price of items for resale.
• Packaging and shipping that you pay per order.
• Payment processing fees and marketplace commissions charged per sale.
• Sales commissions paid on each deal.
• Direct labor only if it is paid per unit or per hour worked on the order, not a fixed salary.

Leave out rent, salaries, insurance, subscriptions and other costs that stay the same whether you sell one unit or one thousand. If a cost is partly fixed and partly variable, split it or use a reasonable estimate.

Using the Ratio

• Estimating profit from growth. If you sell 100 more units at 30 contribution each, profit rises by about 3,000, assuming fixed costs do not change. The ratio lets you do the same with revenue: an extra 10,000 of sales at a 60 percent ratio adds about 6,000.
• Comparing products. Rank products by contribution per unit and by ratio. A product with a high ratio but low volume may matter less than one with a lower ratio and large sales, so look at both.
• Judging discounts. A 20 percent discount on a 50 item cuts price to 40 and contribution to 20, a drop of one third, even though the price fell by only a fifth. Run the discounted price through the calculator before offering a promotion.
• Break-even. Divide fixed costs by contribution margin per unit to get break-even units, as the Break-Even Point Calculator does.

Edge Cases and Limits

• Blank or non-numeric fields are treated as zero.
• If price is zero, the ratio is shown as 0 percent instead of an error.
• If variable cost is higher than price, the contribution margin is negative: each sale loses money and more volume makes it worse.
• The calculation assumes a constant price and per-unit variable cost. Volume discounts, tiered supplier prices and mixed product lines change the average, so use a weighted average for a mix of products.

Treat the result as a planning tool. For pricing decisions with big financial consequences, cross-check your cost classification with an accountant.

Frequently Asked Questions