Why this number is usually smaller than you think

Revenue only really lands in your pocket on the orders that don't come back. Your cost, the marketplace's fee, shipping and any ad spend are all paid whether or not that happens — so a return doesn't just cost you the item, it wipes out everything you'd have made on that sale. Spread that risk across every order and you get one honest number instead of a surprise at the end of the month.

The one formula behind all of it

Profit per sale = Price × (1 − return rate − fee rate) − cost − shipping − ads. Everything else on this page is a rearrangement of that same idea.

Two different lines worth knowing

There's the price where you stop losing money (break-even), and the price where you hit the margin you actually want (target). Selling at break-even isn't a strategy — it's a warning sign that you're one bad month away from trouble. This tool shows you both so you know exactly how much room you have before a "sale price" turns into a loss.

Forget the "good ROAS" benchmarks

Every rule of thumb you've heard about a "healthy" ROAS assumes a margin it never tells you about. The only ROAS that matters is the one calculated from your own numbers: your contribution margin (price minus cost, fee and shipping) sets a hard floor. Below it, every ad dollar you spend loses money regardless of how good the campaign looks. Above it, you're in genuinely profitable territory.

ROAS or ACOS — same line, two ways of saying it

Amazon sellers usually think in ACOS (ad cost as a share of sales); everyone else tends to think in ROAS (revenue per ad dollar). They're just inverses of each other, so this tool gives you both.

The fee is rarely just the headline percentage

eBay and Etsy both stack a flat per-order charge on top of their percentage fee, which hits cheaper items disproportionately hard — a $0.30 flat fee is nothing on a $100 sale and enormous on a $8 one. Amazon's 15% referral fee is a common default, but real categories range from about 8% to 17%, so always check your specific category before pricing off this estimate.

Reorder by the calendar, not by the shelf

Waiting until you're visibly low on stock means you're already too late — by the time a new order clears customs or a supplier's queue, you could be sitting on zero inventory for weeks. The reorder point is the stock level where you should place the next order right now, so it arrives before you actually run out.

What the safety buffer is for

Suppliers run late. Demand spikes without warning. The safety buffer is extra coverage on top of your expected lead time, specifically to absorb those surprises without a stockout.

Price to your margin, not to a round number

Picking a wholesale price by feel usually means underpricing — cost plus "a bit extra" quietly erodes your margin the moment overhead ticks up. Setting the price from your target margin guarantees the number actually protects your business, no matter what the cost happens to be that month.

Why a retail multiplier is included

Retailers typically double or more the wholesale price to cover their own margin (a "keystone" markup is 2x; many categories run 2.2–2.5x). Giving them a suggested retail price up front makes your product easier to place in their catalog and keeps everyone's math consistent.

Margin and fee both come off the same price

If you sell through a marketplace, its fee is calculated on the price you charge — not on your cost. That means the fee and your margin are competing for the same slice, and pricing without accounting for both is how sellers end up with a "40% margin" product that actually nets 30%.

Why charm pricing, and how it's rounded

Prices ending in .99 consistently outsell round numbers by a small but real margin in most retail categories — it's one of the best-tested tricks in pricing psychology. Checking the box rounds your price up to the next whole dollar minus a cent, so you never accidentally undercut your target margin by rounding down.

The discount is only half the story

A bundle only beats selling items separately when what it saves you — one shipment instead of several, one set of marketplace fees instead of several — outweighs the discount you're giving the customer to buy it as a set. A generous-looking discount can still be more profitable than selling separately, if it's replacing enough duplicate shipping and fees.

A percentage off comes straight out of margin, not revenue

"25% off" sounds like a marketing line, but it's really a direct cut into your profit — because your costs don't discount along with the price. On thinner-margin products, a deep discount can wipe out most or all of your per-sale profit even while the item keeps selling.

The core formulas

Marketplace fee presets

Assumptions worth knowing

A note on accuracy

These are the standard formulas a profit spreadsheet would use, not a substitute for your actual seller account numbers. Marketplace fees vary by category, account tier and fulfillment method — always check your own dashboard for the exact rate on a specific listing before pricing off an estimate here.