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Ecommerce Toolkit
ACOS and ROAS Calculator
Measure ad efficiency and compare campaign ACOS with your break-even level based on target margin.
ACOS and ROAS planning guide for ecommerce ads
ACOS (Advertising Cost of Sale) and ROAS (Return on Ad Spend) are the two primary efficiency metrics for ecommerce ad campaigns on Amazon, Flipkart, and D2C channels. ACOS = Ad Spend ÷ Ad-attributed Revenue × 100, expressed as a percentage. ROAS = Ad-attributed Revenue ÷ Ad Spend, expressed as a multiplier. They represent the same relationship from opposite angles: a 25% ACOS equals a 4× ROAS.
Break-even ACOS and its relationship to margin. Break-even ACOS equals your product's net margin percentage — the point at which ad cost exactly consumes all available profit and the campaign neither adds to nor subtracts from overall profitability. If your net margin on a product is 30%, any ACOS above 30% means the campaign is spending more than it earns at the product level. Use the break-even output on this page to set a ceiling on acceptable ACOS before campaign launch and during bid optimization. Running ACOS below break-even signals a profitable campaign; running above it means ads are subsidised by non-ad revenue or are in a deliberate growth/launch phase.
TACoS vs. ACOS: the key distinction. ACOS measures ad efficiency against ad-attributed revenue only. TACoS (Total Advertising Cost of Sale) = Total Ad Spend ÷ Total Revenue (both ad-attributed and organic). For established products with strong organic rank, TACoS is lower than ACOS because organic sales dilute the ad spend share. For new launches where nearly all sales are ad-driven, ACOS and TACoS are close. Tracking TACoS over time reveals whether ad spend is building organic velocity or whether the product is permanently dependent on paid traffic — a critical distinction for sustainable marketplace growth.
Using break-even ACOS for bid optimization. If your break-even ACOS is 28% and a keyword is running at 40% ACOS, you are losing margin on every conversion from that keyword. To approach break-even, reduce the bid by the percentage overage: at 40% vs 28% target, reduce bid by roughly 30% (1 − 28/40). Repeat this calculation per keyword during weekly bid reviews. Avoid making daily bid changes — campaign algorithms need 7–14 days of data to stabilize after a bid change before the new ACOS level is representative.
- Track ACOS trend over time across periods, not single-day or single-week spikes.
- Use break-even ACOS as a profitability floor, not an aspirational target.
- Combine ACOS analysis with the Profit Margin Calculator to ensure break-even inputs reflect real unit economics.
- Monitor TACoS alongside ACOS to measure whether ad spend is building organic rank over time.
ACOS & ROAS FAQ
What is a good ACOS for ecommerce ads?
A good ACOS depends on your profit margin. As long as ACOS stays at or below your margin percentage, the campaign is profitable.
How is ROAS different from ACOS?
ROAS is the inverse of ACOS expressed as a ratio. A 25% ACOS equals a 4x ROAS. Both measure ad efficiency from different perspectives.
Should I optimize for ACOS or ROAS?
Both represent the same relationship. Amazon Ads uses ACOS, while Google and Meta use ROAS. Pick the metric your platform reports.
What is TACoS and how is it different from ACOS?
TACoS (Total Advertising Cost of Sale) = Total Ad Spend ÷ Total Revenue, including both ad-attributed and organic sales. ACOS uses only ad-attributed revenue in the denominator. For established products with strong organic rank, TACoS is lower than ACOS because organic sales dilute the ad cost share. For new launches where almost all sales are ad-driven, the two metrics are close. Tracking TACoS over time shows whether ad spend is building organic velocity or whether the listing remains permanently dependent on paid traffic.
How do I use break-even ACOS to set maximum keyword bid limits?
Break-even ACOS tells you the maximum fraction of revenue you can spend on ads before the campaign becomes loss-making. If a keyword's current ACOS exceeds your break-even level, reduce the bid proportionally: new bid ≈ current bid × (break-even ACOS ÷ current keyword ACOS). Apply this adjustment weekly rather than daily — campaign algorithms need 7–14 days after a bid change to stabilise before the new ACOS level is representative. Keywords that remain above break-even after multiple reduction cycles should be paused or moved to negative keyword lists.
Why does ACOS vary so much between products even in the same campaign?
ACOS varies by product because conversion rate, average selling price, and competitive bid pressure differ per listing. A higher-priced product with the same cost-per-click generates lower ACOS because the revenue per conversion is larger. Products with strong review counts and high conversion rates also generate more revenue per ad impression, reducing effective ACOS. For accurate campaign management, calculate break-even ACOS per individual ASIN using that product's actual margin rather than applying a single target across your full catalog.