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ROAS and MER both compare revenue with marketing spend, but they should not be used for the same decision.
ROAS usually looks at attributed revenue from a campaign, channel, or platform. It is useful when you want to compare campaign-level efficiency. MER looks at total revenue divided by total marketing spend. It is useful when attribution is messy and you need a business-level view.
A campaign can have strong platform ROAS while total MER falls if attribution overstates incremental revenue. A store can have stable MER even when one channel's reported ROAS moves around.
Use the ROAS Calculator at /tools/roas-calculator when reviewing a specific campaign. Use the MER Calculator at /tools/mer-calculator when reviewing total marketing efficiency. For mixed channel reporting, also compare with the Blended ROAS Calculator at /tools/blended-roas-calculator.
ROAS vs MER: when to use each metric
ROAS and MER both connect marketing spend to revenue, but they answer different questions.
ROAS usually looks at attributed revenue from a campaign, channel, or platform. It is useful when you want to compare campaign-level efficiency. MER looks at total revenue divided by total marketing spend. It is useful when attribution is messy and you need a business-level view.
A campaign can have strong platform ROAS while total MER falls if attribution overstates incremental revenue. A store can have stable MER even when one channel's reported ROAS moves around.
Use the ROAS Calculator at /tools/roas-calculator when reviewing a specific campaign. Use the MER Calculator at /tools/mer-calculator when reviewing total marketing efficiency. For mixed channel reporting, also compare with the Blended ROAS Calculator at /tools/blended-roas-calculator.
ROAS
MER
Paid Marketing
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Useful tools
Blended ROAS Calculator
Calculate blended ROAS from total revenue and total ad spend across channels.
MER Calculator
Calculate marketing efficiency ratio from total revenue and total marketing spend for blended paid marketing performance.
ROAS Calculator
Calculate return on ad spend from ad revenue and campaign spend, then see how much revenue each dollar of advertising produced.
AOV Calculator
Calculate average order value from total revenue and number of orders for ecommerce, ads, and store performance reporting.
ROI Calculator
Calculate ROI percentage and net return from revenue and investment cost.
CPC Calculator
Use this free CPC calculator to estimate cost per click from total ad spend and clicks across paid marketing campaigns.