eCommerce Profit Margin Calculator

Key facts

• Margin is profit divided by selling price; markup is profit divided by product cost. A $10 cost sold at $20 is a 50% margin and a 100% markup.
• Amazon and Walmart charge a referral fee (15% in most categories) plus a fulfillment fee; Shopify and Stripe charge 2.9% + 30 cents on the Basic plan.
• Break-even price = per-unit costs divided by (1 minus the fee percentage).
• Physical product brands typically net 15% to 30% per unit after fees and ads.

Last updated September 7, 2026. Fee presets, payout timing, and Onramp Funds eligibility and fee example checked against the published sources listed at the end of this page.

How to use the profit margin calculator

This calculator works at the unit level. Choose your platform first: Amazon and Walmart load a referral fee and a fulfillment fee, Shopify and the other cart platforms load payment processing and your own shipping cost. Enter your selling price and every cost that attaches to one sale, and it returns net profit per unit, net margin, markup, and break-even price. Switch to Find my price to enter a target margin instead and see the price that delivers it.

• Product cost: landed cost per unit, including inbound freight and duties.
• Shipping and packaging: outbound cost per unit when you ship it yourself. On Amazon FBA or Walmart WFS this is zero and the fulfillment fee field covers it.
• Fulfillment fee per unit: FBA, WFS, or 3PL pick-and-pack fees, filled in by the platform preset.
• Marketplace and payment fees: the percentage taken from each sale, such as an Amazon referral fee or card processing.
• Fixed fee per order: flat charges per order, such as a payment processor fixed fee or a per-item closing fee.
• Ad cost per unit sold: total ad spend divided by units sold, optional but recommended if you run paid traffic.

Margin versus markup

These two numbers get confused constantly and the mistake is expensive. Margin is profit divided by selling price. Markup is profit divided by cost. A product that costs $10 and sells for $20 has a 50% margin and a 100% markup. If a supplier or a channel manager talks in markup and you price in margin, you will misprice by a wide gap.

What makes this calculator different

Every number on this page has a time dimension. Other calculators tell you whether something is profitable; this one also shows the cash timeline: when the money goes out, when the platform pays you back, the week your cash position bottoms out, and how much you need to cover the gap. Three other things worth knowing:

• Platform presets: choose Amazon, Shopify, Walmart, TikTok Shop, WooCommerce, BigCommerce, Squarespace, Shopline, or Stripe and the fee and payout-delay fields fill in from published rate cards. Every preset is editable.
• Import your own export: upload a payments, settlement, or orders report from Amazon, Shopify, Walmart, or TikTok Shop and the calculator fills in revenue, fees, refunds, and payout timing from your actual data. The file is read in your browser and never uploaded anywhere.
• Compare two scenarios: duplicate your inputs into Scenario B, change one thing, and see both results and both cash curves side by side.
• Share or save: copy a link that reopens the calculator with your exact numbers, or save the result as a PDF. Your inputs carry over to the other calculators on this site, and nothing is stored on our servers.

The formulas

Total cost per unit = product cost + shipping + fixed fees + ad cost + (selling price × fee percentage). Net profit per unit = selling price minus total cost per unit. Net margin = net profit divided by selling price. Break-even price = costs that do not scale with price, divided by (1 minus the fee percentage).

In price mode, the required price = per-unit costs divided by (1 minus fee percentage minus target margin). If fees plus target margin reach 100%, no price can hit the target.

Reading the result

A net margin above 25% per unit gives room for promotions, returns, and ad spend swings. Between 10% and 25% is workable but leaves little slack. Under 10% means a single fee increase or a discount to clear stock wipes out the profit. Run the numbers again with a 10% coupon applied to see how thin the cushion really is.

From unit economics to inventory

Once you know profit per unit, the next question is how many units you can afford to buy before the cash from sales comes back. Onramp Funds funds inventory purchases for ecommerce sellers with a flat fee disclosed upfront and repayment as a percentage of sales. No personal credit check. Estimate the full cost of your next purchase order, or see your funding offer.

Sources

• Amazon selling fees and FBA rate card
• Shopify plans and payment processing rates
• Walmart Marketplace referral and WFS fees
• TikTok Shop US Seller Center (fees and payouts)
• Stripe pricing
• Onramp Funds: how it works, eligibility, and fee example

Frequently asked questions

What margin should I target?

Most physical product brands aim for 20% to 30% net per unit after fees and ads. Consumables with repeat purchase can run lower because customer lifetime value carries the math.

Where do Amazon storage fees go?

Divide your monthly storage bill by units sold that month and put the result under fixed fees per unit.

Does this calculator store my data?

No. Everything runs in your browser and nothing is saved.