Net Profit Calculator (After All Fees, Ads, and Taxes)

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.

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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]