Free ecommerce calculators, built for sellers who run on spreadsheets
Every tool below is free, requires no account, and computes entirely in your browser. Fee rates are prefilled from published platform pricing — sourced and dated on our sources page — and every formula is documented on the methodology page. Start with profit (know which SKUs earn), then timing (know when to reorder them).
If you are new here, a sensible first hour looks like this: run one product through the True COGS calculator to see what a unit really costs after fees, ads and returns; feed that margin into the break-even and ROAS calculators to sanity-check your fixed costs and ad spend; then switch to the inventory column — safety stock first, reorder point second, and finish with the latest order date, which turns everything into a calendar day you can act on. Marketplace sellers should also run their platform’s fee calculator once — the gap between sticker margin and fee-true margin is usually the biggest surprise on this page.
Inventory & restocking
- Reorder Point CalculatorWork out the exact inventory level that should trigger your next purchase order: daily sales × supplier lead time + safety stock. Free reorder point calculator, no signup.
- Safety Stock CalculatorCalculate how many buffer units protect you from demand spikes and late suppliers, using the max-sales × max-lead-time method. Free safety stock calculator, no signup.
- Latest Order Date CalculatorThe one question no dashboard answers: the last calendar day you can place a PO before this SKU stocks out. Current stock, sales speed, lead time in — a date out.
- Inventory Turnover CalculatorInventory turnover ratio and days of inventory on hand from your annual COGS and average inventory value. See if your cash is moving or parked on shelves.
Profit & fees
- True COGS CalculatorCalculate your true COGS per unit — landed cost, marketplace fees, payment fees, ad spend, returns and packaging — and see your real gross margin per order.
- Etsy Profit CalculatorSee your real profit per Etsy order after transaction, listing, payment processing and Offsite Ads fees — 2026 rates with sources.
- Shopify Profit CalculatorCalculate net profit per Shopify order after card processing, your monthly plan cost amortized per order, shipping and product cost.
- Amazon FBA Profit CalculatorEstimate net profit per FBA unit after the referral fee, FBA fulfillment fee and inbound shipping. Enter your own fee tier — rates sourced and dated.
- TikTok Shop Fee CalculatorBreak down TikTok Shop marketplace commission and payment costs to see your payout and net profit per sale. Editable rates with sources.
- Break-Even CalculatorHow many orders until your store covers its fixed costs? Break-even units and revenue from contribution margin.
- Supplement Brand Profit CalculatorPer-bottle profit for supplement brands: COGS, fulfillment, payment fees, ad CAC and returns — with category-typical defaults you can edit.