E-commerce Calculators for Online Sellers

Running an online store means living and dying by your margins. Marketplace fees, payment processing, shipping, returns, and ad spend each chip away at the price tag — and most sellers only discover the damage when a quarterly report lands. The calculators below are built for the daily reality of Shopify, Amazon, Etsy, and eBay sellers: instant answers, transparent formulas, and no spreadsheet juggling.

Use them to set prices that actually clear a profit, model a flash sale before you commit, or audit a marketplace fee schedule against your costs. Every tool runs entirely in your browser — no signup, no tracking of your numbers, and no upsell to a paid tier. Pick the calculator that matches your decision and you'll have a defensible number in under a minute.