Merchant math, all of it
Every number your store runs on — calculated free
100+ calculators across pricing, fees, advertising, shipping, inventory and cash flow. Each one shows its formula, handles the platform's real fee structure, and needs no signup.
Advertising & ROAS
Break-even and target math for paid traffic.
- Break-even ROAS Calculator Any platform — the generic version with editable per-order costs.
- Amazon Break-even ACOS Calculator The exact ACOS ceiling for your Sponsored Products campaigns — after referral and FBA fees, not before.
- Shopify Break-even ROAS Calculator The ROAS your Meta and Google campaigns must clear once processing, shipping and fulfillment are paid.
- TikTok Shop Break-even ROAS Calculator Commission plus affiliate cuts eat margin fast at TikTok price points — know your floor before you scale spend.
- Dropshipping Break-even ROAS Calculator Ads are your biggest cost — which makes your break-even ROAS the single number your store lives or dies on.
- Etsy Break-even ROAS Calculator Etsy stacks three separate fees on every sale — your ad break-even starts after all of them.
- Google Ads ROAS Calculator The ROAS your Google Shopping and Search campaigns have to clear before Target ROAS bidding starts spending at a loss.
- Facebook Ads ROAS Calculator The ROAS your Meta campaigns must clear once product, shipping and fees are paid — the floor your ROAS goal should never dip below.
- ROAS Calculator How many dollars of revenue every ad dollar brings back — the first number any paid campaign has to answer for.
- ACOS Calculator The share of every ad-driven sale that went straight back to the ad platform — Amazon PPC's favorite scoreboard.
- Target ROAS Calculator Work the bid target backwards from the profit you want to keep — instead of borrowing a ROAS goal from a blog post.
- CPC Calculator What each visitor from paid traffic actually costs — the unit price of attention.
- CPM Calculator The wholesale price of attention — what a thousand pairs of eyes cost before anyone clicks.
- CPA Calculator The price of one customer — the number your margin has to beat for paid acquisition to make sense.
- CTR Calculator The percentage of people who saw your ad and cared enough to click — the fastest read on whether creative is working.
- TACOS Calculator Ad spend measured against everything you sell — the metric that reveals whether ads are building a brand or propping one up.
- Ad Budget Calculator Start with the revenue you want and the efficiency you can realistically buy — the budget is just the division.
- PPC Profit Calculator ROAS says the campaign looks good; this says whether each paid order actually puts money in the bank.
- ROAS to ACOS Converter Google speaks ROAS, Amazon speaks ACOS — this translates one campaign scoreboard into the other.
- CPM to CPC Calculator Impressions are what you buy, clicks are what you want — this converts the price of one into the price of the other.
Pricing & Margins
Margins, markups, discounts and break-even points — the math that sets every price.
- Profit Margin Calculator Margin is the share of every sale you actually keep — the number every other decision in your store depends on.
- Markup Calculator Cost-plus pricing done right — and translated into the margin the markup actually produces.
- Selling Price Calculator Start from the margin you need to survive — then let the price be whatever makes that true.
- Discount Calculator The sale price in one step — and a reminder of what the markdown quietly does to your margin.
- Break-even Units Calculator How many sales until the month stops costing you money — the first number a new product or store must know.
- Margin vs Markup Calculator Two percentages, one profit — and an expensive mistake when they get swapped.
- Keystone Pricing Calculator The oldest rule in retail — double the cost — plus the exact profit and margin that doubling leaves you.
- Wholesale Price Calculator What retailers pay you, and what is actually left per unit after they take their cut of your retail price.
- GMROI Calculator How many gross margin dollars every dollar tied up in inventory earns per year — retail’s favorite buying yardstick.
- Price Increase Calculator Every dollar of a price increase is pure profit — here is exactly how much a raise adds per unit and to your margin.
- Bundle Pricing Calculator Price the bundle so the customer sees a real deal while your blended margin stays healthy.
- Unit Price Calculator The only fair way to compare pack sizes — what one unit actually costs, whatever the box says.
- Gross Profit Calculator What is left after the products pay for themselves — the dollars that fund everything else in the business.
- VAT Price Calculator The tax-inclusive price UK and EU customers must see — computed from your net price in one step.
Marketplace & Payment Fees
What Amazon, Etsy, eBay, Shopify and payment processors really take from each sale.
- Amazon FBA Profit Calculator What one unit actually earns after Amazon takes its referral fee and FBA fulfillment fee.
- Amazon Referral Fee Calculator The commission Amazon takes off the top of every sale — before fulfillment costs even start.
- Etsy Fee Calculator Etsy's three separate fees, added up honestly — and the effective percentage they really take.
- eBay Fee Calculator The final value fee plus the per-order charge — what a sale actually leaves in your account.
- PayPal Fee Calculator What PayPal takes from a payment — and the exact amount to invoice so the fee lands on the payer instead.
- Stripe Fee Calculator The 2.9% + 30¢ math on every card charge — and the gross-up trick for when the net amount is what matters.
- Shopify Fee Calculator What Shopify Payments takes from each order — and the effective rate once the 30¢ fixed fee is counted.
- Square Fee Calculator The Square fee on any transaction — online, invoiced, or tapped — and what actually reaches your bank.
- TikTok Shop Fee Calculator TikTok Shop's referral commission on each order — before any affiliate cut you promise creators.
- Walmart Marketplace Fee Calculator Walmart's referral fee on each marketplace sale — with no monthly subscription to amortize.
- Mercari Fee Calculator Mercari's selling fee and payment processing charge combined into one honest payout number.
- Poshmark Fee Calculator The two-tier Poshmark fee — flat $2.95 under $15, 20% above — resolved into your actual earnings.
- Depop Fee Calculator Depop's selling fee plus payment processing, combined into the number that hits your account.
- Gumroad Fee Calculator Gumroad's flat cut on each digital sale — and what a price point really pays out.
- Amazon Storage Fee Calculator What Amazon charges every month just to keep your units in the FBA warehouse — the fee that quietly compounds on slow-selling inventory.
- Shopify Profit Calculator What a Shopify order actually leaves in your pocket once product cost, shipping and Shopify Payments are all paid — not just the processing fee.
Unit Economics
CAC, LTV, AOV and contribution — whether each customer earns more than they cost.
- Customer Acquisition Cost (CAC) Calculator What one new customer actually costs you — the number every ad budget and LTV comparison hangs on.
- Customer Lifetime Value (LTV) Calculator What a customer is really worth over their whole relationship with your store — in margin, not just revenue.
- LTV to CAC Ratio Calculator One ratio that says whether your growth engine builds value or quietly burns it.
- Average Order Value (AOV) Calculator How much the average checkout is worth — the fastest lever for growing revenue without buying more traffic.
- Revenue Per Visitor (RPV) Calculator What each visit to your store is actually worth — conversion rate and order value collapsed into one honest number.
- Contribution Margin Calculator What every single sale contributes toward your fixed costs and profit — the true per-unit scoreboard.
- CAC Payback Period Calculator How long each new customer leaves you out of pocket — the cash-flow truth behind a pretty LTV:CAC ratio.
- Churn Rate Calculator The share of customers slipping out the back door while marketing pours new ones in the front.
- Customer Retention Rate Calculator The percentage of customers who stay — the quiet engine behind every store with strong lifetime value.
- Purchase Frequency Calculator How often the average customer actually comes back — the multiplier hiding inside your lifetime value.
- Customer Lifetime Orders Calculator How many orders — and how many dollars — the average customer relationship will produce end to end.
- Refund Rate Calculator The share of orders that come back — and the revenue that quietly leaves with them.
Shipping & Landed Cost
Landed cost, duty and freight — the true per-unit cost of getting goods to the door.
- Landed Cost Calculator The factory price is not your cost — landed cost is what a unit really costs by the time it reaches your warehouse.
- Import Duty Calculator Duty is the tax the border collects on your goods — know it before the invoice does.
- Customs VAT Calculator Import VAT is charged on more than your goods — the taxable base includes freight and duty too.
- Dimensional Weight Calculator Carriers bill the size of your box or the weight of it — whichever costs you more.
- Shipping Cost per Unit Calculator A freight invoice only becomes useful once it is divided into the units it moved.
- Freight Cost Calculator The headline rate per CBM is never the real rate — fixed charges see to that.
- CBM Calculator Cubic meters are the currency of ocean freight — every quote starts with this number.
- Chargeable Weight Calculator Air freight bills the heavier of two weights: the one on the scale and the one your box implies.
- Container Utilization Calculator A container costs the same full or half-empty — utilization tells you which one you booked.
- Shipping Margin Calculator Shipping is a line item with its own P&L — most stores have never checked whether it is profit or subsidy.
- Free Shipping Threshold Calculator The right free-shipping minimum is not a round number — it is the point where extra order value pays for the label.
- Total Import Cost Calculator One number for the whole shipment — everything the import costs, and what that means per unit.
Inventory
Reorder points, EOQ and turnover — holding enough stock without drowning in it.
- EOQ Calculator The order size where ordering costs and holding costs balance — buy less and you pay in paperwork, buy more and you pay in warehouse space.
- Reorder Point Calculator The stock level that says "order now" — early enough that the new shipment lands before the shelf goes empty.
- Safety Stock Calculator The buffer that absorbs a hot sales week or a late container — sized from your real worst case, not a guess.
- Inventory Turnover Calculator How many times a year your inventory converts back into cash — the speed metric behind healthy stock levels.
- Days of Inventory Calculator How many days of selling your current stock represents — the countdown clock version of inventory turnover.
- Sell-Through Rate Calculator What share of the stock you brought in actually sold — the fastest verdict on a buy, a season, or a product launch.
- Stock to Sales Ratio Calculator How many dollars of inventory you hold for every dollar of monthly sales — the retail buyer’s early-warning gauge.
- Inventory Holding Cost Calculator The rent your inventory quietly pays every month it sits on the shelf — storage, capital, insurance, and shrinkage combined.
- Dead Stock Cost Calculator Dead stock is not just a write-off waiting to happen — it is frozen cash that keeps charging you rent while it waits.
- Fill Rate Calculator The share of orders you could ship immediately from stock — the customer’s-eye view of how good your inventory planning really is.
- Weeks of Supply Calculator The sell-out countdown for a SKU — the number to check against your supplier’s lead time before every reorder.
- Inventory Shrinkage Calculator The gap between what your system says you own and what the shelf count actually finds — theft, damage, and paperwork errors, priced.
Conversion & Email
Conversion rates, cart abandonment and email ROI — squeezing more from existing traffic.
- Conversion Rate Calculator The single percentage that tells you whether your traffic problem is actually a website problem.
- Cart Abandonment Cost Calculator Every abandoned cart had a wallet behind it — this is what those walk-aways add up to each month.
- Email ROI Calculator Email is usually the highest-ROI channel a store owns — this puts your own number on that claim.
- Email List Growth Calculator Lists shrink by default — churn eats 20–30% a year — so growth only counts after subtracting the leavers.
- Open Rate Calculator The first gate every email must pass — measured against delivered mail, not the number you sent.
- Email Click Rate Calculator Clicks are the email metric money follows — and click-to-open tells you whether the fault is the subject line or the content.
- A/B Test Significance Calculator Before you ship the winner, check whether your test found a real difference or just measured noise.
- Bounce Rate Revenue Loss Calculator Visitors who leave after one page never see your checkout — here is what that exit door costs in dollars.
- Popup Conversion Calculator Your popup is the front door of your email list — this measures how many visitors actually walk through it.
- Revenue per Email Calculator Opens and clicks are proxies — revenue per email sent is what a send is actually worth.
Store Finance
Cash cycles, runway and growth — the money mechanics behind the storefront.
- Cash Conversion Cycle Calculator How many days each dollar stays trapped between paying suppliers and collecting from customers.
- Working Capital Calculator The cushion between what you own and what you owe over the next twelve months.
- Runway Calculator The one number every founder should know without looking it up: how many months until zero.
- Burn Rate Calculator Turn a bank-balance drop into the monthly and daily rate your business actually spends.
- MRR Growth Calculator Month-over-month MRR growth — the compounding heartbeat of any subscription business.
- Revenue Growth Calculator Compare any two periods on the same footing: the growth rate and the dollar change at once.
- Net Profit Calculator What is actually left after products and overhead both take their share of revenue.
- Operating Margin Calculator How much of every revenue dollar the core business keeps before interest and taxes.
- ROI Calculator One percentage that makes an ad campaign, a bulk inventory buy, and a new tool comparable.
- Break-even Revenue Calculator The revenue line where the month stops losing money — in monthly and per-day terms.
Merchant Tools
Generators and checkers for the daily grind: links, codes, SKUs, slugs, limits.
- UTM Link Builder If the link isn't tagged, the sale has no source — and your best channel looks identical to your worst.
- Discount Code Generator Single-use codes stop coupon-site leakage — but nobody types 500 of them by hand.
- SKU Generator A SKU scheme invented ad hoc at product #5 becomes a warehouse mystery at product #500.
- Product URL Slug Generator The URL is the first thing search engines read about a product page — make it say something.
- Marketplace Character Counter Every marketplace truncates at a different length — and truncation is where clicks go to die.
- Barcode Generator Turn a SKU or product number into a real, scannable barcode — no account, no watermark, nothing uploaded.
SellersCalc is a free suite of 100+ calculators and tools covering every number an online store runs on. Price a product from a target margin, see what Amazon, Etsy or Stripe really keeps from a sale, find the ad spend where campaigns stop losing money, work out the landed cost of an imported unit, your reorder point, your runway, your break-even revenue — then handle the daily grind with the UTM builder, discount-code and SKU generators. Every calculator shows its formula next to its result, runs entirely in your browser, and needs no account.