ROAS is simple to calculate but easy to misinterpret. This guide shows you the correct formula, a worked example, and how to calculate the number that actually matters — profit ROAS.
Return on Ad Spend (ROAS) measures how much revenue is generated for every pound spent on advertising. It is the most widely used metric in digital marketing and one of the most frequently misapplied. Here is how to calculate it correctly and how to extend the calculation to produce a commercially meaningful figure.
A 3.8x ROAS means every £1 of ad spend generated £3.80 of revenue. Most advertising platforms (Google Ads, Meta) report ROAS automatically in their dashboards.
Revenue ROAS ignores the cost of the goods or services being sold. At a 45% gross margin, a 3.8x ROAS generates £1.71 of gross profit per £1 of spend — a strong commercial return. At a 20% gross margin, the same 3.8x ROAS generates £0.76 of gross profit per £1 of spend — marketing is destroying value at the gross profit level.
Break-even ROAS is the minimum revenue ROAS required for marketing to cover its own cost in gross profit terms. Calculated as: 1 ÷ gross margin.
| Gross Margin | Break-even ROAS | Minimum target ROAS |
|---|---|---|
| 20% | 5.0x | 6.5x |
| 25% | 4.0x | 5.5x |
| 30% | 3.3x | 4.5x |
| 40% | 2.5x | 3.5x |
| 50% | 2.0x | 3.0x |
Calculate ROAS separately for each channel — Google Ads, Meta, email, LinkedIn, exhibitions. Apply your gross margin to each to get profit ROAS per channel. Rank by profit ROAS. The bottom 20-30% of channels by profit ROAS should be cut or paused before any budget increase is considered. Reallocating from the lowest to the highest performer typically improves blended performance by 30-50% without increasing total spend.
The LumixAI Marketing ROI Tracker does this automatically — enter spend and revenue per channel along with your gross margin, and it returns profit ROAS, break-even ROAS, and a performance verdict for each channel. See the full ROAS guide for more context.
A good ROAS depends on your gross margin. At 40% gross margin, break-even ROAS is 2.5x — so a target of 3.5x or above is strong. At 25% gross margin, break-even is 4x, so you need at least 5x to generate a meaningful return. Always calculate profit ROAS, not just revenue ROAS.
ROAS measures revenue return on ad spend. ROI measures profit return on total investment. ROAS ignores product costs. ROI accounts for them. Profit ROAS bridges the gap — it applies gross margin to ROAS to give a gross profit return figure.
Google Ads reports ROAS automatically as Conv. value / cost in the Campaigns tab. This is revenue ROAS. To get profit ROAS, multiply the reported ROAS by your gross margin percentage.
Meta ads typically generate lower ROAS than Google Search because they reach people who are not actively searching. A profitable Meta campaign at 40% gross margin needs to achieve above 2.5x ROAS to cover ad costs in gross profit terms. Most SMEs should target 3x+ on Meta.
The LumixAI Marketing Analysis tool calculates profit ROAS per channel using your gross margin. Free trial included.
Calculate your profit ROAS →