E-Commerce Contribution Margin, POAS & Break-Even ROAS Calculator
Interactive financial unit-economics modeller calculating net contribution margin, Profit on Ad Spend (POAS), break-even ROAS and scaling scenarios.
E-Commerce Unit Economics & POAS Profit Architecture
Simulates unit economics flow: Gross Revenue → COGS → Shipping & Fulfillment → Merchant Gateway Fees → Return Allowances → Ad Spend = Net Contribution Margin ($) and Profit on Ad Spend (POAS).
E-Commerce Contribution Margin, POAS & Break-Even ROAS Calculator Configurator
D2C Apparel & Fashion — POAS & Break-Even ROAS Calculation
Standard unit-economics model for D2C Apparel & Fashion with $120.00 AOV, 35% COGS, 6% return rate, and $30.00 target CPA.
1 Input Parameters & Assumptions
| Parameter | Value | Context & Provenance |
|---|---|---|
| Average Order Value (AOV) | $120.00 AUD / USD | Standard baseline order basket value |
| Target Ad Spend (CPA) | $30.00 AUD / USD | Target customer acquisition cost in ad channels |
| Cost of Goods Sold (COGS) | 35.0% % of AOV | $42.00 direct manufacturing and product cost |
| Payment Gateway Fee | 2.9% + $0.30 % + fixed | $3.78 per-transaction gateway fee (Stripe/Shopify Payments) |
| Merchant-Paid Shipping | $8.50 $ / order | Outbound courier freight and postage overhead |
| 3PL Pick & Pack Fulfillment | $4.20 $ / order | Warehouse handling, packaging and boxing cost |
| Return & Refund Allowance | 6.0% % of orders | Apparel return rate (effective revenue factor = 0.94 → $112.80) |
2 Explicit Mathematical Formula
Effective Revenue = AOV × (1 - Return Rate) = $120.00 × 0.94 = $112.80
Variable Costs = COGS ($42.00) + Gateway Fee ($3.78) + Shipping ($8.50) + Fulfillment ($4.20) = $58.48
Gross Contribution Margin (CM2) = Effective Revenue - Variable Costs = $112.80 - $58.48 = $54.32 (45.27% of AOV)
Break-Even CPA Cap = Gross Contribution Margin = $54.32
Break-Even ROAS = AOV / Break-Even CPA = $120.00 / $54.32 = 2.21x
Net Contribution Margin = Gross CM - Target CPA = $54.32 - $30.00 = $24.32 (20.27% of AOV)
Profit on Ad Spend (POAS) = Gross CM / Target CPA = $54.32 / $30.00 = 1.81x
Reported Platform ROAS = AOV / Target CPA = $120.00 / $30.00 = 4.00x3 Computed Output Metrics
| Computed Metric | Result | Interpretation & Threshold |
|---|---|---|
| Gross Contribution Margin (CM2) | $54.32 / order (45.27%) | Gross profit available to cover customer acquisition and fixed overhead |
| Break-Even ROAS | 2.21x ROAS Floor | Minimum platform ROAS required to avoid losing money (Max CPA: $54.32) |
| Net Contribution Margin | $24.32 / order (20.27%) | Net retained bottom-line profit after ad spend and all variable costs |
| Profit on Ad Spend (POAS) | 1.81x POAS Multiplier | True gross profit generated per ad dollar spent (>1.0x indicates profitable unit economics) |
| Total Variable Costs | $58.48 / order (48.73%) | Combined COGS ($42.00), gateway ($3.78), shipping ($8.50), and 3PL ($4.20) |
| Reported Platform ROAS | 4.00x Reported ROAS | Top-line ROAS displayed in Meta/Google Ads dashboard ($120 AOV / $30 CPA) |
E-Commerce Contribution Margin, POAS & Break-Even ROAS Calculator — Scope & Limitations
Explicit operational boundaries and constraints defining target use cases and out-of-scope scenarios.
Built For (Target Use Cases)
- Unit-economics modeling for transactional D2C and e-commerce brands with variable COGS, shipping, fulfillment, and payment gateway costs.
- Calculating true Contribution Margin (CM1, CM2, CM3), Break-Even ROAS, and Profit on Ad Spend (POAS) against blended paid acquisition spend.
- Establishing maximum allowable CPA caps and target POAS thresholds for Meta Ads and Google Performance Max bidding strategies.
Not Built For (Limitations & Out-of-Scope)
- Subscription/SaaS recurring revenue models requiring multi-year churn amortization or lifetime value (LTV) cohort discounting.
- Econometric Media Mix Modeling (MMM) across non-linear brand awareness channels (use lightweight-mmm-pipeline instead).
- Enterprise GAAP financial accounting covering fixed overheads (rent, executive payroll, SG&A) beyond direct order fulfillment.
Operational Assumptions & Defaults
- Assumes unit variable costs (COGS %, gateway fee %, shipping cost, fulfillment cost) are incurred per gross order shipped.
- Payment gateway variable fee percentage is calculated directly on headline AOV, plus fixed per-transaction fee.
- Return rate discounts effective revenue into effective AOV, while variable production and shipping costs apply to the full gross order.
E-Commerce Contribution Margin, POAS & Break-Even ROAS Modeler
Performance Media & FinanceModel genuine unit economics factoring in COGS, gateway fees, shipping, pick-pack fulfillment, and return rates. Calculate your real Break-Even ROAS cap, Net Contribution Margin, and Profit on Ad Spend (POAS).
Unit Economics & Spend Inputs
Key Profit & Efficiency Metrics
Per-Order Cost & Margin Breakdown
- Gross Revenue (AOV):$120.00
- Less Returns & Refunds (6%):-$7.20
- Cost of Goods Sold (COGS):-$42.00
- Payment Gateway Fee:-$3.78
- Shipping & Fulfilment:-$12.70
- Gross Contribution Margin:$54.32 (45.3%)
- Advertising Spend (Target CPA):-$30.00
- Net Contribution Margin:$24.32 (20.3%)
Monthly Scaling Projections ($15,000.00 Spend)
CPA Sensitivity & POAS Profit Curve
| CPA Scenario | CPA | POAS | Net Profit/Ord | Monthly Profit |
|---|---|---|---|---|
| -30% | $21.00 | 2.59x | $33.32 | $23,790.48 |
| -15% | $25.50 | 2.13x | $28.82 | $16,946.16 |
| Current Target | $30.00 | 1.81x | $24.32 | $12,160.00 |
| +15% | $34.50 | 1.57x | $19.82 | $8,601.88 |
| +30% | $39.00 | 1.39x | $15.32 | $5,882.88 |
Export Financial Model & Target ROAS Matrix
Export your customized unit economics model to CSV, generate a shareable URL for your executive team, and set break-even target ROAS thresholds in ad platforms.
Unit economics model and target ROAS/CPA thresholds by product tier.
{
"unit_economics": {
"aov": 120.00,
"cogs_pct": 32.0,
"shipping_pick_pack": 9.50,
"gateway_fee_pct": 2.2,
"gateway_fee_fixed": 0.30,
"return_rate_pct": 3.5,
"break_even_roas": 1.74,
"break_even_cpa": 68.96,
"target_poas_multiplier": 1.50
}
}Replacing Surface ROAS with Net Contribution Margin
Platform-reported ROAS from Google Ads and Meta Ads flatters digital performance by ignoring cost of goods sold (COGS), payment gateway transaction fees, picking and packing, shipping overhead, and return rates. This calculator reveals true net profit per acquired customer.
POAS Modeling & Margin-Based Bidding
Traditional Return on Ad Spend (ROAS) calculates revenue divided by ad spend. In high-cost retail environments, top-line revenue hides negative cash flow on discounted or low-margin inventory.
Calculation Framework
- Contribution Margin 1 (CM1): Gross Revenue minus Cost of Goods Sold (COGS) and merchant transaction fees.
- Contribution Margin 2 (CM2): CM1 minus variable shipping, warehouse pick/pack, and return processing costs.
- Profit on Ad Spend (POAS):
CM2 / Total Ad Spend. A POAS above 1.0 indicates profitable unit economics after all variable fulfillment expenses.
Setting Value-Based Bidding Rules
When feeding conversion values into Google Ads or Meta Ads:
- Pass dynamically calculated gross profit rather than total basket value into transaction tags.
- Apply margin brackets by product category so smart bidding algorithms hunt for profitable volume rather than high-revenue, low-margin transactions.
Related Resources
- Combine with our Google Ads Budget Pacing Script to control daily ad investment.
- Review our adidas APAC Performance Case Study for value-based bidding applied to enterprise eCommerce.
Changelog
- 1.0.0 (2026-08-01T08:00:00+10:00): Initial release with dynamic ROAS/POAS sensitivity modelling and return rate factor.
POAS & Contribution Margin Sanity Checks
Validate unit economics calculations against monthly financial P&L statements and ad platform reported ROAS.
Pre-Production Verification Checklist
Ensure merchant processing fees (Stripe/PayPal 2.2% + $0.30) and return allowances are included in variable cost deductions.
Confirm Break-Even ROAS = 1 / (1 - (COGS % + Shipping/AOV + Fee % + Return %)).
Ensure target ad platform ROAS exceeds Break-Even ROAS by target POAS profit multiplier (e.g. 1.3–1.6x).
Terminal Diagnostic & Debug Commands
Calculates exact break-even ROAS from CLI based on unit economics parameters.
node -e 'const aov=120, cogs=0.32, ship=9.5, fee=0.024, ret=0.035; const cm=(aov*(1-cogs-fee-ret)-ship)/aov; console.log("Break-Even ROAS:", (1/cm).toFixed(2));'Failure Remediation & Troubleshooting
Cause: Ignoring high product return rates (e.g. 20% in fashion) and heavy shipping fulfillment costs.
Fix: Incorporate net return rates and fixed pick-pack costs into POAS calculation before setting target bid strategies.
How to cite and attribute this tool
MIT LicenceThis resource is free, open and un-gated under the MIT Open Source Licence. You are encouraged to use, integrate and cite it with attribution:
@misc{geraghty_ecommerce_contribution_margin_poas_calculator,
author = {Geraghty, Gordon},
title = {E-Commerce Contribution Margin, POAS & Break-Even ROAS Calculator},
year = {2026},
url = {https://gordongeraghty.com/resources/performance-media/ecommerce-contribution-margin-poas-calculator},
note = {Head of Performance Media, Empire Amplify}
}Changelog & Version History
v1.0.0Initial release with dynamic ROAS/POAS sensitivity modelling and return rate factor.
Strategic Takeaway & Operational Guidelines
Platform-reported ROAS (4.00x) flatters performance by ignoring 48.73% in variable order costs and a 6.0% return allowance. While top-line metrics suggest high efficiency, true net margin is $24.32 per order (POAS 1.81x). Scale ad spend only while platform ROAS remains comfortably above the 2.21x break-even floor.