E-Commerce Margin Calculator: Pricing, Break-Even and ROAS

Net margin, break-even point and minimum ROAS for an online store

Net profit per sale is the pre-tax price − (purchase cost + net shipping + payment fees + returns allowance + acquisition cost), and the break-even point is the monthly fixed costs divided by that profit. For a product sold at 49.90 including VAT, with 12.08 of net profit per sale and 1,500 of fixed costs, you need 125 sales a month to break even.

The formulas

Pre-tax price = price incl. VAT ÷ (1 + VAT rate). Payment fees = (price incl. VAT + shipping charged to the customer) × rate + fixed fee. Net shipping = shipping and packaging − shipping charged to the customer, never below zero. Returns allowance = (purchase cost + shipping and packaging) × return rate. Variable cost per sale = purchase cost + net shipping + payment fees + returns allowance + customer acquisition cost (CAC). Net profit per sale = pre-tax price − variable cost. Break-even = monthly fixed costs ÷ net profit per sale, rounded up. Minimum ROAS = pre-tax price ÷ (pre-tax price − variable cost excluding CAC): below it, advertising costs more than it brings in.

Worked example (default values)

• price of 49.90 incl. VAT, i.e. 41.58 before tax and 8.32 of VAT at 20%;
• payment fees: 49.90 × 1.5% + 0.25 = 1.00;
• variable cost: 12 + 4.50 + 1.00 + 12 = 29.50;
• net profit: 12.08 per sale, or 29.1% of the pre-tax price;
• break-even: 1,500 ÷ 12.08 = 125 sales a month, or 6,237.50 incl. VAT;
• minimum ROAS: 41.58 ÷ 24.08 = 1.73;
• at 150 sales: 7,485 of revenue incl. VAT and 313 of profit after fixed costs.

The price multiplier (4.16) divides the price incl. VAT by the purchase cost.

Assumptions and limits

The tool measures a store's overall profitability: it includes fixed costs (subscriptions, apps, salaries) and an average CAC. Returns and shipping charged to the customer, both 0 by default, count once you enter them; try several prices incl. VAT to set a product’s price from its full landed cost. Income tax is not included. Default fees match Stripe's standard EEA cards; premium or non-EEA cards cost more. Results are indicative and are not accounting advice.

Sources and dates: Stripe France pricing page as displayed on 14/10/2026: 1.5% + 0.25 for standard EEA cards, 2.8% + 0.25 for premium cards, 3.15% + 0.25 for international cards; French standard VAT rate of 20% (Article 278 of the General Tax Code, in force since 01/01/2014) (checked on 14/10/2026).

Frequently Asked Questions

How do I calculate an online store's break-even point?

Divide your monthly fixed costs by the net profit of one sale, then round up. With 1,500 of fixed costs and 12.08 of net profit per order, you need 125 sales a month, or 6,237.50 of revenue including VAT. If profit per sale is zero or negative, the tool reports that break-even cannot be reached.

What is a campaign's minimum ROAS?

It is the ratio of pre-tax revenue to ad spend below which advertising loses money. The tool calculates it as pre-tax price ÷ margin before marketing, 41.58 ÷ 24.08 = 1.73 with the default values. A campaign at a ROAS of 1.5 would therefore sell at a loss.

Does a price multiplier of 4 guarantee profitability?

No, it only accounts for the purchase cost. With the default values, the multiplier is 4.16 and net profit is 12.08 per sale; if acquisition cost rises from 12 to 24, the same multiplier leaves just 0.08 per sale.

Are payment fees calculated on the price including VAT?

Yes. The tool applies the percentage to the price paid by the customer, VAT included, and then adds the fixed fee: 49.90 × 1.5% + 0.25 = 1.00 per order with Stripe's standard EEA card rates as displayed on 14/10/2026.

How do I include returns in the margin calculation?

Enter your return rate: on each sale, the tool sets aside the purchase cost and shipping of returned products. With the default values and 4% returns: (12 + 4.50) × 4% = €0.66 per sale, and net profit drops from €12.08 to €11.42. At 10%, the allowance rises to €1.65.

What does free shipping cost my margin?

The tool deducts the shipping charged to the customer from shipping and packaging, never going below zero, and applies payment fees to the amount collected. With the default values, free shipping leaves €12.08 of net profit per sale; charging €3.90 for shipping raises it to €15.93, and break-even falls from 125 to 95 sales a month.

What price multiplier should an online product aim for?

The tool divides the price including VAT by the purchase price excluding VAT and shows “ideal” from 4, “fair” between 3 and 4 and “too low” below: an internal benchmark, not a standard. At €49.90 for a €12 purchase, the multiplier is 4.16, but the net margin is only 29.1% of the pre-tax price once advertising is paid.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.