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ROAS is revenue, not profit, and that distinction has sunk more campaigns than bad targeting ever did.

A 3x return on ad spend sounds healthy. On a product with a 25 percent margin it is losing money — three rupees back for every one spent, but only seventy-five paisa of that three is yours. Subtract your cost of goods and delivery before deciding a campaign works.

The number to know is your break-even ROAS: one divided by your margin. At a 25 percent margin that is 4x. Below it you are paying for the privilege of shipping orders.

The input that does the most damage

Conversion rate. Everything downstream depends on it and it is where optimism does the most harm.

If you do not have your own data, take the most pessimistic figure you can defend rather than an industry average. Published averages are dragged upward by mature accounts with years of optimisation behind them, and they are not describing your first month.

Cost per click

Varies enormously by sector, and competitive commercial terms can cost many times what an informational one does. Use keyword planner figures for your own market rather than a national headline number.

What the model leaves out

This is a straight line. Real campaigns have wasted spend on irrelevant search terms, a learning period before performance settles, and seasonality. Expect the first month to underperform the model and the third to beat it.

If you have lifetime value data

Use it as the order value instead of a single purchase. For anything with repeat business it usually changes the picture completely — campaigns that look marginal on first-order revenue are often comfortably profitable once the second order is counted.