We just shipped 12 free ecommerce profit calculators

Most of the "ecommerce profit calculators" floating around the web are not built for the question operators actually need to answer. They tell you that a 60 percent gross margin is healthy. They do not tell you whether the specific SKU you are about to discount by 25 percent and ship to Zone 8 with a 14 percent return rate is going to make money.

I built Agentis because that gap is where mid-market Shopify Plus brands quietly bleed margin. And while we were working on the real-time enforcement product, the team kept running into the same problem on the marketing side: every public calculator we linked to was either too generic to be useful or locked behind a 12-field lead form. So we shipped our own. Twelve of them. All free, no email gate, no signup.

Here is the full set, with one-line context for each.

The 12 calculators

• Profit margin calculator — the basic one done right, with separate gross and net lines so you can see where the leak actually lives.
• Break-even calculator — figure out how many units you have to ship at your current contribution margin to cover fixed cost.
• Contribution margin calculator — strips revenue down to what is actually variable, which is the only number worth optimizing at the SKU level.
• True product cost calculator — landed cost including freight, duty, packaging, and the costs your COGS field on Shopify is almost certainly missing.
• CAC payback calculator — how many months until a new customer turns positive given your AOV, contribution margin, and repeat rate.
• ROAS to profit calculator — translates a paid-media ROAS into actual contribution dollars after COGS, fees, and returns.
• Shopify Plus fees calculator — full Plus fee model including the revenue-share tier most merchants forget to model above $20M GMV.
• Amazon FBA fees calculator — referral, FBA fulfillment, storage, and the long-tail fees that quietly compound.
• Freight zone impact calculator — what shipping a $40 product to Zone 2 versus Zone 8 actually does to your per-order margin.
• Return rate impact calculator — adjusts your headline gross margin for return-driven cost: reverse logistics, restocking, write-offs, and the orders you never recover.
• Discount impact calculator — how much incremental revenue you need to break even after a 10, 15, or 25 percent promo.
• Subscription margin calculator — LTV-aware margin for subscription brands that have to model churn cohorts, not single orders.

The four that matter most

If you only look at four, look at these. They are the ones that exist nowhere else on the public web in a form that is actually credible.

The discount impact calculator is the one I wish more CFOs ran before approving promo campaigns. A 25 percent off promo on a 55 percent gross margin SKU needs roughly 83 percent more unit volume to stay flat in contribution dollars. That is the math operators do not see until the month-end P&L lands.

The freight zone impact calculator bakes in dimensional weight pricing and zone-based rate cards, so you can finally answer the "why is the same product unprofitable in California and fine in Texas" question without exporting six months of orders into a spreadsheet.

The return rate impact calculator is brutal in the right way. A category-leading 60 percent gross margin in fashion with a 28 percent return rate is closer to 36 percent realized margin once you include reverse logistics and restocking. Most merchants are running on the headline number.

The ROAS to profit calculator is the one paid teams should be staring at every Monday. A 4x ROAS sounds healthy until you net out 45 percent COGS, 3 percent payment fees, 2 percent fulfillment, and a 12 percent return rate, at which point you are funding Meta to break even.

Where static calculators stop and Agentis starts

A calculator is a thinking tool. It tells you what your floor is. It does not stop a real order from violating that floor at checkout three minutes from now.

That is the gap Agentis fills. The same numbers you can plug into the profit margin calculator live inside our policy engine, except we sync them in from your ERP, push them to the edge as a pre-computed lookup, and enforce them on every Shopify Plus checkout in under 10 milliseconds. If a discount stack drops a cart below your minimum contribution margin, the order does not ship at a loss — it bumps to the next valid discount tier or blocks the offending code, automatically.

Static calculators are what you use to set the policy. Agentis is what enforces it. Neither one alone is enough for a brand that is doing eight-figure GMV through Shopify Plus.

Use them, link to them, break them

Every calculator above is free, with no lead capture and no rate limit. If you find a number that does not match the way your finance team models the same metric, tell us — we would rather fix the formula than defend a bad assumption. The whole point is to give operators tools that match the messy reality of running an ecommerce P&L, not to publish another generic "what is gross margin" widget.

If your Shopify Plus checkout is leaking margin and you want to see exactly where — at the order level, on real traffic — start a free 7-day audit. No rewrite, no commitment. You give us read-only access for a week, we hand back a report showing every order shipped under your floor and the dollar value of the leak. The calculators tell you what should be true. The audit tells you what actually is.