Every Forvendo calculator in one place. Each one runs in your browser, needs no signup, and pairs with a full guide and a free downloadable sheet. Pick the one that matches the decision in front of you.
Cost and pricing
Shopify Fee Calculator
Total monthly Shopify cost and cost per order from plan subscription, payment processing, and the third-party gateway transaction fee. Full cost stack in How Much Does Shopify Really Cost?
Etsy Fee Calculator
Listing, transaction, US payment processing, and Offsite Ads fees applied to one order, so you can see what you actually keep. Related: Does Etsy Send You a 1099-K?
eBay Fee Calculator
The final value fee for the category, the per-order fee, and the extras that change it, with sales tax and shipping in the fee base the way eBay charges it. Related: Does eBay Send You a 1099-K?
eBay Profit Calculator
Profit, margin and ROI after eBay’s fees, the shipping label and packaging, plus the break-even price, the price for a target margin, and the most you can pay for an item.
PayPal Fee Calculator
PayPal’s US rates for Checkout, Goods and Services, cards, Pay Later and invoices, with international payments and Instant Transfer, from what the buyer pays or back from what you want to receive.
Whatnot Fee Calculator
Commission at your tier under the rates Whatnot introduced in September 2026, plus the payment processing fee on the buyer’s whole order, and what you keep.
Profit Margin Calculator
Net profit per order and net margin after product cost, shipping, processing, and ad spend, plus gross margin, markup, and the break-even price.
Shopify Shipping Calculator
Turns average order value, margin, and label cost into a starting free-shipping threshold and flat rate. Full method in Shopify Shipping Rates: A Margin-First Decision System.
Tax and compliance
1099-K Tax Calculator
Walks the gross figure on the form to two numbers: the net receipts your return should start from and the payouts your bank should show. Full method in Does Shopify Send You a 1099-K?
Self-Employed Estimated Tax Calculator
The safe-harbor amount from prior-year tax, split across the four quarterly due dates. Full method in Do You Have to Pay Quarterly Taxes on Shopify Income?
Self-Employment Tax Calculator
Schedule SE line by line: net earnings, the Social Security and Medicare parts, the deductible half, and the 0.9% Additional Medicare Tax from Form 8959, for 2026 and 2025.
Sales Tax Nexus Thresholds by State
Economic-nexus thresholds for all 50 states and DC, with a checker for how close you are to each one. Full method in the Multi-State Sales Tax guide.
Inventory
Reorder Point Calculator
The stock level at which to place the next purchase order, from daily sales velocity, supplier lead time, and a safety buffer. Full method in the Reorder Point SOP.
App spend health check
See whether your app stack is inside the 3–6%-of-MRR band. This one has no page of its own, so it runs here. Full framework in the Shopify App Decision Framework and the App Stack Audit.
App Spend Health Check
Planning heuristic for solo stores; the 3–6%-of-MRR band is a guideline, not a rule.
Forvendo · every other Friday
One operating decision, worked through with numbers
The same approach this calculator takes: the sources named, the assumptions shown, and the arithmetic left where you can check it.
No spam, unsubscribe any time. The calculators and every download stay free whether you subscribe or not.
Want the full versions?
These calculators cover the most common decision in each area. For the complete working sheets — multi-tab workbooks with trackers, audits, and worked examples — see the free resources page. Every calculator here is a slice of a deeper free tool.