How to Use the Marketplace Fee & Ad Cost Profit Calculator
Selling on an online marketplace looks simple on paper — price minus cost equals profit — but payment processing fees and pay-per-click ad spend can quietly eat away a big chunk of that margin. Card and digital wallet processing typically runs 2.5-3.5%, and ranking well in search often means paying for CPC ads on top of that. This calculator takes your price, cost, monthly units sold, payment fee rate, and monthly ad spend, and returns revenue, net profit, and your real margin rate in one step.
The math: gross profit (price minus cost, times units) minus payment fees (revenue times fee rate) minus ad spend equals net profit. If the resulting margin looks thin, consider adjusting your price, trimming spend on underperforming keywords, or reallocating your ad budget toward keywords that actually convert.
Ad spend is largely a fixed cost regardless of revenue, so it hits margin hardest when sales volume is low. As unit sales grow, ad spend becomes a smaller share of revenue — run a few different volume scenarios through this calculator to find your break-even point.
Frequently Asked Questions
Check your marketplace's seller dashboard or payout statement for the payment processing fee by method (card, digital wallet, etc). It's usually 2.5-3.5%. Add any other transaction fees to get one combined rate.
It means your cost and ad spend are too high relative to your price. Consider raising your price, cutting spend on low-converting keywords, or reallocating budget toward keywords that convert best.