Guides
The detail behind each calculator: how the number is built, why the fees apply, and what actually moves it. Every guide sits on the page with the tool it explains.
42 guides across 6 areas.
Seller fees
What each marketplace and payment processor really takes from a sale.
Marketplace fees compared: where sellers actually keep the most
A 2026 marketplace fee comparison on one identical order: Shopify, Etsy, eBay, Amazon, Walmart, TikTok Shop, Poshmark and PayPal ranked by what you actually keep.
Includes the Marketplace Fee Comparison CalculatoreBay fees explained: how to calculate your real profit per sale
eBay fees explained for 2026: the 13.25% final value fee, the $0.40 per-order fee, category rates, Store costs and ad rates, with take-home figures from $10 to $10,000.
Includes the eBay Fee CalculatorPayPal fees explained: how much does PayPal really take?
PayPal fees explained for 2026: the 2.99% + $0.49 US rate, what you net on $10 to $10,000, micropayments, cross-border costs, refunds and how to pay less.
Includes the PayPal Fee CalculatorEtsy fees explained: how to work out your real profit per sale
Etsy fees explained for 2026: the 6.5% transaction fee really costs 9.6-14% once listing and payment fees land. Effective rates, worked examples, eBay comparison.
Includes the Etsy Fee CalculatorAmazon FBA profit explained: how to find your real margin and ROI
Amazon FBA fees explained for 2026: referral rates by category, fulfilment fees by size tier, storage, returns and ads, and the real profit, margin and ROI.
Includes the Amazon FBA Profit CalculatorShopify fees explained: how to calculate your real profit per sale
A plain-English breakdown of every Shopify fee, subscription, payment processing, and transaction fees, with worked examples and ways to pay less.
Includes the Shopify Fee CalculatorStripe fees explained: what you really pay and what you keep
Every Stripe fee for 2026: the 2.9% + $0.30 base rate, international card and currency conversion surcharges, disputes, payouts, and how to work out your true net.
Includes the Stripe Fee CalculatorTikTok Shop fees explained: what sellers really pay in 2026
TikTok Shop fees in 2026: the 6% referral fee, what you net on $10 to $500 orders, creator commissions, ads, returns, and how it compares to eBay and Amazon.
Includes the TikTok Shop Fee CalculatorWalmart seller fees: how much Walmart takes from each sale
How much Walmart takes per sale: the 6% to 15% referral fee on item price only, fee and net tables from $10 to $500, WFS, returns, ads, Walmart vs Amazon.
Includes the Walmart Marketplace Fee CalculatorPoshmark fees explained: how much Poshmark takes on every sale
Poshmark takes $2.95 under $15 and 20% from $15 up. Fee and payout table from $5 to $500, the $15 pricing trap, offers, bundles and real profit math.
Includes the Poshmark Fee CalculatorProfit & pricing
Margin, landed cost, discounts and the numbers behind a pricing decision.
How to calculate profit margin, markup and net margin
Calculate profit margin, markup and net profit margin. Markup to margin chart, prices for a target margin, the COGS formula and units to hit a profit goal.
Includes the Profit Margin CalculatorWhat a discount really costs: promotion margin explained
Why a 30% discount can cost half your profit, how many extra sales a promotion needs to be worth running, and the deepest discount your margins can actually survive.
Includes the Discount Margin CalculatorAmazon ROI explained: the number that beats margin
Amazon ROI calculator guide: the exact formula, a worked FBA example, ROI vs margin, inventory turns, benchmarks by sourcing model and break-even selling price.
Includes the Amazon ROI CalculatorLanded cost explained: what imported inventory really costs you
How to calculate landed cost for imported inventory: freight, customs duty, CIF vs FOB, insurance, brokerage, and the per-unit number your pricing should actually be based on.
Includes the Landed Cost CalculatorHow to calculate break-even point, contribution margin and margin of safety
Break-even in units and revenue, contribution margin ratio, target profit units, margin of safety, marginal cost and payback period, with worked tables.
Includes the Break-Even CalculatorRestocking fees explained: what you actually get refunded
What a restocking fee is, typical rates by category, whether restocking fees are legal, what Amazon, eBay and Best Buy charge, and how much of your refund survives.
Includes the Restocking Fee CalculatorMarketing metrics
The advertising funnel end to end, impressions through to lifetime value.
ROAS explained: what return on ad spend really tells you about profit
ROAS is revenue divided by ad spend. Calculate your ROAS, breakeven ROAS and POAS, see why 4x profits at a 45% margin but loses money at 20%, and fix it.
Includes the ROAS CalculatorBreakeven ROAS explained: the number every ad campaign needs
What breakeven ROAS means, the exact formula, how to work out your target ROAS and maximum CPA, and the mistakes that make advertisers scale losing campaigns.
Includes the Breakeven ROAS CalculatorCPA explained: what a cost per acquisition is actually worth
CPA calculator: work out your cost per acquisition, the breakeven maximum CPA, the target CPA that leaves real profit, and why platform CPA understates it.
Includes the CPA CalculatorCPC explained: what a click costs and what a click is worth
CPC calculator: work out your cost per click, the maximum CPC you can profitably bid, and cost per conversion, plus how CPM, CTR and margin set the price.
Includes the CPC CalculatorCPM explained: what cost per 1,000 impressions really costs you
CPM calculator and guide: work out cost per 1,000 impressions, then convert it to implied CPC, CPA and ROAS, because a cheap CPM with a weak CTR is expensive.
Includes the CPM CalculatorCTR explained: what a click-through rate lift is actually worth
CTR calculator and guide: work out click-through rate from impressions and clicks, then price what a CTR lift is worth in extra clicks, orders and revenue.
Includes the CTR CalculatorConversion rate explained: what a 1% lift is actually worth
Conversion rate calculator and guide: work out your CVR, then price what a lift is worth in orders, revenue and gross profit, with benchmarks and sample sizes.
Includes the Conversion Rate CalculatorCAC explained: your real customer acquisition cost and payback period
CAC calculator and guide: work out your true customer acquisition cost including salaries and tools, convert it to a payback period, and see the formula.
Includes the CAC CalculatorLTV explained: customer lifetime value and the LTV:CAC ratio
LTV explained: the customer lifetime value formula, why gross profit LTV beats revenue LTV, what a good LTV:CAC ratio is, and how much you can pay per customer.
Includes the LTV CalculatorLoans & mortgage
Monthly payments, total interest and how much faster you could be debt-free.
How your mortgage payment is calculated (and how to lower it)
How your mortgage payment is calculated, with taxes and insurance, PMI, interest-only, ARM, biweekly, overpayment, prequalification, FHA, VA and UK modes.
Includes the Mortgage CalculatorRefinance break-even: when a mortgage or car refinance pays off
How long a refinance takes to break even, with a table by closing costs and monthly savings, the 30-year term reset, cash-out costs and car refinancing.
Includes the Refinance CalculatorHow car loans work: payments, interest, and the term trap
How a car loan payment is calculated, what the monthly figure is made of, EMI explained, boat, ATV and RV loans, insurance while there is a lien, and negative equity.
Includes the Auto Loan CalculatorHow long to pay off a loan - and how extra payments help
See how payoff time and total interest are calculated, why minimum payments trap you, and how much extra payments save on credit cards and loans.
Includes the Loan Payoff CalculatorHow to pay off credit card debt: interest, minimum payments and payoff tables
How credit card interest is calculated, why minimum payments take years, payoff tables by balance, APR and payment, balance transfer maths and DTI.
Includes the Credit Card Payoff CalculatorSaving & investing
How money grows over time, and what it takes to hit a target.
How compound interest works (and how to use this calculator)
Simple vs compound interest, every compounding frequency from annual to continuous, the formulas, and how nominal rate, effective rate and APY differ.
Includes the Compound Interest CalculatorHow to calculate ROI (and why annualized return matters more)
Calculate ROI, annualized return and CAGR, plus future value, present value, tax-equivalent yield, and stock and crypto profit after fees. Worked examples.
Includes the Investment ROI CalculatorHow a 401(k) projection works: contributions, match, payouts and claiming age
401(k) balance at 65 by starting age, how an employer match changes it, the 4% rule, annuity payout math and how claiming age changes Social Security.
Includes the Retirement CalculatorHow long it takes to reach a savings goal, and what to save each month
Months to save $5,000, $10,000, $25,000 or $50,000, the monthly amount to hit a goal by a date, emergency fund sizing, sinking funds, 529 plans and inflation.
Includes the Savings Goal CalculatorPay & taxes
Take-home pay, freelance rates, and the tax that comes off the top.
How your take-home pay is calculated (2026)
Understand how your paycheck is calculated in 2026, federal income tax brackets, Social Security, Medicare, pre-tax deductions, and state tax, step by step.
Includes the Take-Home Pay CalculatorHow to convert a salary to an hourly rate (and back)
Convert hourly pay to an annual salary and back. Full $10 to $50 an hour table with annual, monthly, weekly and daily pay, overtime math and offer comparisons.
Includes the Salary to Hourly CalculatorHow to set your freelance rate (so the math actually works)
Freelance rate math for 2026: why salary ÷ 2,080 fails, the correct derivation, required rates at $50k, $200k, self-employment tax, day rates and rush fees.
Includes the Freelance Rate CalculatorSelf-employment tax explained (2026): the table, quarterly dates and what to set aside
Self-employment tax on $20,000 to $200,000 for 2026: 15.3% on 92.35% of net earnings, the $184,500 wage base, quarterly due dates and how much to set aside.
Includes the Self-Employment Tax CalculatorWise vs PayPal vs Payoneer: which one actually pays you more?
A side-by-side comparison of Wise, PayPal, and Payoneer fees for freelancers, including the exchange-rate markup each one hides, with real numbers on a $2,000 payment.
Includes the Wise vs PayPal vs Payoneer CalculatorHow sales tax works (and how to calculate it)
US sales tax explained for 2026: combined state and local rates, how to calculate tax on any price, back tax out of a total, plus nexus and marketplace rules.
Includes the Sales Tax CalculatorHow VAT works: adding and removing value-added tax
VAT explained for 2026: add VAT by multiplying by 1.20, remove it by dividing by 1.20, plus UK and EU rate tables, the £90,000 threshold and reclaim rules.
Includes the VAT CalculatorHow to calculate percentages (the easy way)
Percentage calculator guide: every formula with worked examples, percent of a number, increase, decrease, percentage change, reverse percentages and error.
Includes the Percentage Calculator