ROAS Formula: Revenue Divided by Ad Spend

ROAS formula for revenue and advertising cost

Return on ad spend is attributed advertising revenue divided by the corresponding advertising cost. If a campaign generated $12,000 from $3,000 in spend, ROAS is 4.00x, 400%, or 4:1.

Calculate current ROAS from ad spend and revenue

ROAS formula worked examples

A campaign with $12,000 attributed revenue and $3,000 ad spend has 4.00x ROAS. The same result is 400% or 4:1. If revenue falls to $9,000 while spend remains $3,000, ROAS falls to 3.00x; if spend rises to $4,000 while revenue remains $12,000, ROAS also falls to 3.00x.

For planning, a $7,500 budget at 3.20x target ROAS requires $24,000 attributed revenue. In the reverse direction, $18,000 of attributed revenue at a required 4.50x ROAS supports no more than $4,000 ad spend. These equations define the required relationship but do not forecast demand or platform delivery.

Which ROAS formula should you use?

Use revenue divided by spend to measure a completed period. Use budget multiplied by target ROAS when the question is how much attributed revenue a plan requires. Use revenue divided by required ROAS when the question is how much advertising cost the revenue can support.

Use the margin formulas only when contribution margin is defined before advertising. Break-even ROAS reserves no first-order profit, while target ROAS removes the desired profit share before calculating the advertising allowance. In every case, align currency, dates, campaign scope, conversion event, and revenue basis before comparing the output with a report.

ROAS percentage and ratio conversion formula

Multiply a ROAS multiple by 100 to express it as a percentage. A 3.5x result equals 350%. The ratio format uses the same multiple as 3.5:1, meaning $3.50 of attributed revenue per $1 of ad cost.

Required revenue formula from target ROAS

When ad budget and target ROAS are known, multiply them to find the attributed revenue required to maintain that relationship. This is a planning requirement, not a forecast.

Calculate a target ROAS from contribution margin and profit

Maximum ad spend formula from revenue and ROAS

Divide attributed revenue by the required ROAS to find the largest ad cost that would preserve that return. If revenue is $25,000 and the target is 5.0x, maximum ad spend is $5,000.

Calculate ad budget from a revenue goal

Break-even ROAS and target ROAS formulas

A margin-only break-even estimate is the reciprocal of contribution margin before ads. A profit target subtracts desired profit margin before taking that reciprocal. Use contribution rather than gross margin when shipping, fees, returns, and fulfillment are material.

Calculate break-even ROAS from detailed product costs

ROAS formula for Excel and Google Sheets

If column A contains ad spend and column B contains attributed revenue, enter =IFERROR(B2/A2, "") to return the ROAS multiple while leaving zero-spend rows blank. Format the result as a number such as 4.00, not as a percentage, unless the reporting convention expects 400%.

Use =A2*C2 for required revenue when A2 is budget and C2 is target ROAS. Use =B2/C2 for maximum ad spend when B2 is attributed revenue and C2 is required ROAS. Keep currency, date range, attribution scope, and revenue definition in adjacent columns so the arithmetic is not separated from its assumptions.

ROAS formula limits and common mistakes

• Mixing total revenue with campaign-only ad spend
• Comparing channels with different attribution windows
• Reading 400% as 400x instead of 4x
• Calling attributed revenue profit
• Ignoring VAT, refunds, fees, and product costs
• Averaging channel ROAS values instead of weighting spend and revenue