Margin Guard
Calculates break-even and target CAC from your own Etsy/Shopify cost data — no fixed 2.2x or fee-percentage rule unless you choose one.
$17
Works with the AI tools you already use
Claude Code
Cursor
Codex CLI
GitHub Copilot
Gemini CLI+20 moreClaude CodeCursorCodex CLIGitHub CopilotGemini CLI
OpenClaw
Manus
Grok+17 agentsMargin Guard
Example session with this skill installed
(Synthetic example.) I sell a t-shirt on Etsy. The buyer pays $35.00 with no discount. My Printify base cost is $12.50, supplier shipping is $5.25. Etsy's payment/transaction fee on this order is a real $2.28. My return/reprint buffer is a flat $1.05. I want at least $5.00 profit per order after ad spend. Also: I spent $150 on ads last week but got 0 confirmed orders from that batch — what's my real CAC?
- Read your context and instructions
- Compiled the margin guard
- Generated the document
(Synthetic example — all figures below come directly from running the skill's own script on the inputs above; nothing is estimated.)
Part 1 — break-even and target CAC
| Line item | Amount |
|---|---|
| Amount charged to customer (no discount) | $35.00 |
| Product/fulfillment cost | -$12.50 |
| Supplier shipping cost | -$5.25 |
| Platform/payment processing fee (your real amount) | -$2.28 |
| Return/reprint buffer | -$1.05 |
| Break-even CAC | $13.92 |
| Target profit per order (yours) | $5.00 |
| Target CAC | $8.92 |
Result: MEETS USER-SELECTED THRESHOLD — with the numbers you gave, you can spend up to $8.92 per order on ads and still hit your $5.00 target profit. This is a calculation from the data you entered, not a guarantee.
Part 2 — your real ad spend, 0 confirmed orders
You gave $150.00 in real ad spend and 0 real orders acquired.
Realized CAC: cannot be calculated. With zero orders there is no valid count to divide the spend by. This does not mean your CAC is infinite or zero, and it does not mean the campaign failed; it means there is nothing yet to compute a real CAC from. Your break-even CAC ($13.92) and target CAC ($8.92) above are unaffected because they come from your cost data, not ad performance.
Next step: once you have at least one confirmed order from that ad batch, realized CAC = real spend ÷ real orders. Report back with a number greater than zero and the skill will calculate it.
margin-guard.pdf
PDF · document
Example file from a real run - the skill writes it into your workspace.
Connects securely to your tools. The creator never sees your data.
What you get
About this skill
The problem
E-commerce sellers often ignore landed costs, real platform fees, and the difference between break-even and target CAC — which makes products that look profitable on paper lose money in reality. Manually separating these numbers for Etsy or Shopify across different suppliers is slow and easy to get wrong.
What it does
- Calculates landed cost (product cost + supplier shipping) and separates break-even CAC from target CAC — never the same number.
- Uses your real platform/payment fee (a rate you give, plus its base, or an exact amount) and your real return/reprint buffer — never an assumed or default percentage.
- Handles discounts, VAT/sales tax, and customer-paid shipping as distinct, non-overlapping inputs, so nothing is double-counted.
- If you explicitly choose an example multiple (e.g., "use 2.2x"), evaluates it and always labels it as your own choice — never a system rule. If you choose none, no fixed number is applied.
- States the result as one of four clear states — cannot calculate, negative unit economics, doesn't meet your target, or meets your chosen threshold — never a universal "list / don't list" verdict.
Why this beats prompting it yourself
General AI often blurs break-even CAC, target CAC, and realized CAC into one number, or quietly assumes a platform fee instead of asking for your real one. This skill keeps those three concepts separate, refuses to guess a missing fee or a missing order count, and never substitutes a "standard" threshold for your own numbers.
Use cases
- Checking whether a new Printify product can break even before syncing it to an Etsy storefront.
- Comparing two suppliers' total landed cost side by side, using your own numbers for each.
- Working out the minimum price a Zendrop drop-shipping listing needs to hit your target profit per order.
- Telling apart a pricing problem (negative unit economics) from an advertising problem (CAC too high) before you touch ad spend.
Known limitations
Every number must come from you or an integrated source — the skill never assumes a "standard" Etsy/Shopify fee percentage, a discount basis, or a currency conversion rate; if one of the required inputs is missing or currencies are mixed without a stated rate, it stops and asks rather than guessing. This is not financial, tax, or legal advice, and it does not guarantee sales or profit — verify current platform fees on your own dashboard.
How to install
Works the same in every agent - Claude, Cursor, Codex, Copilot and 20+ more.
- 1
Download the ZIP
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- 2
Unzip into your skills folder
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- 3
Ask your agent to use it
Restart the agent if it was already running. It picks the skill up automatically - no config needed.
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Click the path to copy it. Create the folder if it does not exist yet.
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