The Prompt
Copy and paste into your AI tool
You are a senior ecommerce financial analyst. You know that most Amazon sellers can tell you their revenue but not their net profit — because they stop at contribution margin and never subtract advertising, overhead, and taxes. Your job here is to build a complete per-unit and per-month net profit picture that answers the question: what is this business actually keeping? I'm going to provide my revenue and cost data. Calculate net profit at every layer. LAYER 1: GROSS MARGIN Net revenue per unit = sell price − returns cost (Returns cost per unit = return rate % × (sell price + return processing fee)) COGS per unit = product cost + inbound shipping per unit Gross margin per unit = net revenue per unit − COGS per unit Gross margin % = gross margin per unit ÷ sell price × 100 LAYER 2: CONTRIBUTION MARGIN (after Amazon fees) Amazon fees per unit = FBA fulfillment fee + referral fee + monthly storage fee + (return processing fee × return rate) Contribution margin per unit = gross margin per unit − Amazon fees Contribution margin % = contribution margin per unit ÷ sell price × 100 LAYER 3: MARKETING-ADJUSTED MARGIN (after PPC) PPC cost per unit = total monthly PPC spend ÷ total monthly units sold Marketing-adjusted margin per unit = contribution margin per unit − PPC cost per unit Marketing-adjusted margin % = marketing-adjusted margin per unit ÷ sell price × 100 LAYER 4: OPERATING MARGIN (after overhead) Overhead cost per unit = total monthly overhead ÷ total monthly units sold Operating margin per unit = marketing-adjusted margin per unit − overhead cost per unit Operating margin % = operating margin per unit ÷ sell price × 100 LAYER 5: NET MARGIN (after estimated taxes) Tax per unit = operating margin per unit × effective tax rate % Net margin per unit = operating margin per unit − tax per unit Net margin % = net margin per unit ÷ sell price × 100 Also calculate monthly equivalents for each layer: Monthly [metric] = per-unit [metric] × monthly units sold Output format: NET PROFIT ANALYSIS: [SKU / Product] Monthly units sold: X UNIT ECONOMICS TABLE | Layer | Per Unit | % of Sell Price | Monthly ($) | | Sell Price | $X | 100% | $X | | Returns Cost | −$X | X% | −$X | | COGS | −$X | X% | −$X | | Gross Margin | $X | X% | $X | | Amazon Fees | −$X | X% | −$X | | Contribution Margin | $X | X% | $X | | PPC Cost | −$X | X% | −$X | | Marketing-Adj. Margin | $X | X% | $X | | Overhead | −$X | X% | −$X | | Operating Margin | $X | X% | $X | | Estimated Tax | −$X | X% | −$X | | NET MARGIN | $X | X% | $X | HEALTH CHECK Flag each layer as HEALTHY / MARGINAL / AT RISK based on: - Gross margin: HEALTHY > 50%, MARGINAL 35-50%, AT RISK < 35% - Contribution margin: HEALTHY > 25%, MARGINAL 15-25%, AT RISK < 15% - Operating margin: HEALTHY > 15%, MARGINAL 8-15%, AT RISK < 8% - Net margin: HEALTHY > 10%, MARGINAL 5-10%, AT RISK < 5% BEFORE YOU EXECUTE: 1. If any required input is missing, unclear, or looks malformed, stop and ask me a specific clarifying question before proceeding. Do not guess or fill in plausible values. 2. If I haven't provided an effective tax rate, use 25% as a default and flag it explicitly. Do not provide tax advice — this is a planning estimate only. 3. If I haven't provided overhead data, complete the model through Layer 3 and flag Layer 4 as incomplete. 4. If you are less than 95% confident you understand what I'm asking for, ask me to clarify before executing the task. 5. Verify every arithmetic calculation by working it twice. Do not round intermediate calculations; round final figures to two decimal places. 6. After completing the analysis, flag any layer where you had to make an assumption under a "Caveats" section. ===== PASTE YOUR PRODUCT DATA BELOW. Include: sell price, COGS per unit, inbound shipping per unit, Amazon referral fee %, FBA fulfillment fee, monthly storage fee per unit, return rate %, return processing fee, monthly units sold, total monthly PPC spend, total monthly overhead (all non-Amazon operating expenses), and effective tax rate if known. [YOUR DATA HERE]
Example Input
What you'd paste after the divider
Product: Silicone Spatula Set (3-piece) Sell price: $24.99 COGS per unit: $6.50 Inbound shipping per unit: $0.85 Amazon referral fee: 15% FBA fulfillment fee: $4.75 Monthly storage fee per unit: $0.12 Return rate: 6% Return processing fee: $3.50 Monthly units sold: 320 Monthly PPC spend: $1,840 Monthly overhead (software, VA, misc): $1,200 Effective tax rate: 28%
Tips
01
Most sellers are surprised by how much their per-unit PPC cost is when they divide monthly ad spend by units sold. Divide your total monthly ad spend by total monthly units — that's your true cost of customer acquisition per unit, and it belongs in your unit economics model.
02
The difference between contribution margin and operating margin is often larger than expected. A 30% contribution margin business can have a 10% operating margin or less once advertising and overhead are included — which is why "contribution margin" alone can be misleading.
03
The tax layer is an estimate, not advice. But including it matters: a business with a 12% operating margin at a 25% effective tax rate takes home 9% net — knowing that number shapes how you think about pricing, reinvestment, and growth.
Frequently Asked Questions
What does the Net Profit Calculator (After All Fees, Ads, and Taxes) prompt do?
Calculate what you're actually keeping after every cost layer — COGS, Amazon fees, PPC, overhead, and estimated taxes. Most sellers know their revenue. This prompt tells you what's left after everything comes out.
What data do I need to use this prompt?
An example of the exact input format is provided on this page under "Example Input." Generally you'll prepare your data in the structure shown, paste it after the prompt body, and the AI will return the analysis described above. If you're missing any inputs, the prompt will ask you what it needs.
How long does this take to set up?
Setup time for this prompt is < 30 mins. That includes pulling your data, formatting it to match the example, and running the prompt. Once your data pipeline is set up the first time, subsequent runs take only a few minutes.
Which AI tool should I use this with?
This prompt is designed to work with any major large language model — ChatGPT (GPT-4 or newer), Claude (Sonnet 4 or newer), or Gemini. For structured analysis, math, and tabular outputs, Claude and GPT-4 class models produce the most reliable results.
Does this prompt work for Shopify or other platforms?
This prompt is built for Amazon sellers and references Amazon-specific data points such as referral fees, FBA fulfillment fees, and ASIN-level metrics. The underlying methodology can be adapted to other platforms by substituting equivalent inputs, but the prompt as written is Amazon-first.
What skill level is required to use this prompt?
This prompt is rated intermediate. Some familiarity with your platform's data exports and basic AI prompting is helpful for getting the most out of it. Most ecommerce operators can use it productively within a single session.
Is this prompt free to use?
Yes. Every prompt in the SMB Advantage Prompt Library is free for any small business operator to use. The only cost is whatever you pay for your AI tool subscription (ChatGPT Plus, Claude Pro, etc.).
Stay in the loop
Want notes when new prompts ship?
A few times a week, field notes on what's actually working when AI meets ecommerce ops. Plus first look at new prompts and tools as they go live.
Related Tool
Related Prompts