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Free ecommerce operations calculators
Seven free ecommerce operations calculators for the side of an Amazon, Walmart or Shopify store that ads tools ignore: what messy operations cost you, in-house vs outsourced team cost, fees and margin per unit on each channel, reorder points and stockout cost, Amazon storage and aged fees, WFS storage fees and your cash conversion cycle. Every default shows its source and date, and none of them asks for your email.
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Ecommerce operations calculators for cost and team
These two answer the question most owners start with: what is the current way of working costing me, and what would the alternatives cost?
What do messy operations cost my store each year? It puts a yearly figure on founder time, manual team work, stockouts on top sellers, excess stock, "where is my order?" tickets, order errors and avoidable fees, using your numbers and published benchmarks. 22 inputs in five groups; the default example runs to about $114,000 a year for a $3M store. Illustrative · sample figures.
In-house vs outsourced ops team cost calculatorWhat would a hire, a VA, an agency or a managed team really cost in year one? It adds benefits and payroll costs, hiring time, tools, turnover and the hours you spend managing each option, then shows what each one actually buys.
Fees and margin calculators
Fees change several times a year, and each channel charges for different things. These tools carry the date we last checked each rate.
What does one product earn per unit on each channel after fees? Enter one product to see referral or payment fees, fulfillment, surcharges, contribution margin and break-even ACoS side by side.
Amazon storage, aged inventory and low-inventory fee estimatorWhat will this SKU cost to hold this month, and what will aging add? It applies Amazon's storage, aged inventory surcharge and low-inventory-level fee rules to your units, using the rates from your own Seller Central fee pages.
Walmart WFS storage fee calculatorWhen does WFS stock get expensive? It applies Walmart's standard, peak and long-term storage rates by inventory age and shows when removal or disposal costs less than keeping stock.
Inventory and cash calculators
Stock is where most of a store's cash sits. These two show when to reorder and how long your cash is tied up.
When should I place the next purchase order? It works out lead time including FBA, WFS or 3PL receiving, safety stock, reorder point, days of supply and the daily cost of running out.
Ecommerce cash conversion cycle calculatorHow many days is my cash tied up? It calculates days of inventory, days to collect by channel (including Amazon's payout 7 days after delivery) and days to pay suppliers, then the cash tied up and what each day of improvement frees.
How we build these tools
The rules are the same for all seven, and they are what make the numbers usable.
- Every default carries a label.
Sourced means a published primary or analyst figure. Vendor means a figure published by a company that sells related services, so treat it as an estimate. Example means a placeholder to replace with your own number. Assumption means our own estimate, with the reasoning shown.
- The method is on the page.
Each tool shows its formulas in plain text and a worked example computed from the defaults, so the page makes sense before you type anything and without JavaScript.
- Rates are dated and checked.
Fee tables show the date we last checked them and link the platform's own page. When a rate changes, the tool and the seller rule tracker change on the same day.
- No gate.
No sign-up, no email wall, no pop-up. Copy your summary or download it as CSV.
- Your numbers stay in your browser.
Values you enter may be saved in your browser for convenience. We do not receive them.
- Corrections are welcome.
If a rate or source is wrong, email contact@ecomrelays.com and we fix it.
Under every result: this estimate uses the figures you enter and published rates. It is not an audit, an offer or a promise of savings, sales or profit.
New to the terms these tools use? The glossary defines each one with its formula, and the Learning Center shows when to use each tool.
Want the real numbers?
The calculators run on estimates. A review of your own accounts replaces them with real figures.
- Selling $1M or more a year:
a free Profit Leak Scan prices your margin, inventory, fee and operations leaks from read-only access. Report by email within 48 hours of working access, no sales call required.
- Not live yet, or under $1M:
a free Launch Readiness Check gives you a written plan within 3 business days, with fees and margin per unit on each channel.
For the bigger cost picture, read what outsourcing operations costs in 2026 or see all comparisons.
Are these calculators really free?
Yes. There is no sign-up, no email wall and no paid version. You can copy a summary or download a CSV of your results. If you want someone to replace the estimates with real figures from your accounts, the Profit Leak Scan and Launch Readiness Check are free too, and neither requires a sales call.
How current are the fee rates?
Each rate-based tool shows the date its rates were last checked and links the platform's own fee page. Every rate change we find is logged in the seller rule tracker, and the tool changes the same day. Where a platform has not published a rate we could confirm, the tool asks you to enter it from your own fee page instead of guessing.
Do you store the numbers I enter?
No. The tools run in your browser. Values may be kept in your browser's own storage so they are still there when you come back, and clearing your browser data clears them. Nothing you type is sent to us unless you choose to email it.
Which calculator should I start with?
If you are weighing a hire against outside help, start with the in-house vs outsourced calculator. If you are not sure where money is going, start with Cost of Chaos. If you are launching a product, start with the fee and margin calculator, then the reorder point calculator.
Can I trust vendor figures used as defaults?
Treat them as estimates. Every vendor figure is labeled with the vendor's name and date, because companies that sell related services publish them. Replace any default with your own number; the result updates and the method stays the same.
Why do the results say they are not a promise?
Because they are arithmetic on your inputs and published rates, not an audit of your accounts. A calculator cannot see your contracts, your exemptions or the errors in your data. Use the result to decide what to look at first, then check the real figures.
Sources4 sources
- 01marketplacelearn.walmart.comupdated May 27, 2026; checked Oct 20, 2026Primary
- 02shopify.comchecked Oct 20, 2026Primary
- 03sell.amazon.comchecked Oct 20, 2026Primary
- 04bls.govJune 2026 data; checked Oct 20, 2026Primary
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