Ecommerce finance · private local CSV
SKU contribution, line by line.
Group duplicate SKU rows and calculate the dollars and percentage left after the variable costs in your export.
Contribution = net sales − variable costs. Contribution margin = contribution ÷ net sales × 100. Use a Total variable costs column or recognized cost components, not both.
How to analyse SKU contribution margin
- Export your SKU economics as a CSV with at least SKU and net sales columns.
- Choose the currency: USD, CAD, GBP or EUR.
- Press Analyze local CSV.
- Review the contribution dollars and margin percentage for each SKU.
How the margin is calculated
Contribution margin is net sales minus variable costs, and the ratio is that amount divided by net sales. It shows what each product leaves to pay for fixed costs and profit, which makes it more useful than gross margin when fulfilment, marketplace fees and advertising are large parts of the cost of selling.
If your file has a Total variable costs column, it is used on its own. Otherwise the analyser adds only the recognised cost columns: COGS, fulfilment, shipping, marketplace fees, payment fees, ad spend, returns cost and other variable cost. Duplicate SKU rows are combined before the margin is worked out, and all costs are treated as totals for the period, not per-unit rates. The page does not invent missing costs, fixed overhead or tax.
Your sales data stays private
The analyser runs in your browser, inside an isolated frame on this page that has no network access. Your file is read and written back by your own device, so it is not uploaded to TNAADO or anyone else, and nothing is stored. The advertising on this page sits outside the frame and cannot see what you choose. Sales and cost data are commercially sensitive and are never uploaded.
- Limits: 15 MB, 50,000 data rows, 200 columns and 50,000 characters per field.
- Check units and periods before comparing SKUs.
CSV method
If Total variable costs exists, it is used alone. Otherwise the analyzer sums only recognized cost columns. Duplicate SKU rows are combined before margin is calculated. All cost fields are period totals, not per-unit rates. The page does not infer missing costs, fixed overhead or tax.
Official formula source: Shopify: Contribution margin vs. gross margin, checked 15 October 2026. Shopify describes contribution margin as net sales less variable costs, divided by net sales for the ratio.
Private by design
The file is processed locally and is never uploaded. The isolated tool frame executes no advertising, analytics, AI or third-party code.