Northstar Calculators logoNorthstar Finance
Finance · Small business and commerce

Incremental Advertising ROAS Calculator

Evaluate the change associated with an ad test by subtracting the revenue you expected without the campaign. This is not the same as dividing all attributed sales by ad spend.

$
Supported range: 0–1000000000000. Revenue in the test group or period being assessed.
$
Supported range: 0–1000000000000. Your counterfactual estimate for the same scope and period.
$
Supported range: 0.01–1000000000000. Spend included in this test.
%
Supported range: 0–100. Share of incremental revenue remaining after variable costs.

Method and assumptions

Incremental revenue = observed revenue − baseline revenue. Incremental ROAS = incremental revenue ÷ positive ad spend. Incremental contribution after ads = incremental revenue × entered contribution margin − ad spend. Break-even lift = ad spend ÷ positive contribution-margin fraction; a zero margin is rejected because the break-even revenue is undefined.

Worked example

Observed revenue of $5,000 less a $3,200 baseline yields $1,800 incremental revenue. With $600 spend, incremental ROAS is 3.0. At a 60% contribution margin, contribution after ads is $480; $1,000 incremental revenue would cover the spend.

How to use the result

A positive result depends on a credible baseline. This arithmetic does not establish causal lift; seasonality, concurrent promotions, attribution windows, and customer mix can distort the comparison.

Input meanings and limits

  • Revenue observed during campaign: Revenue in the test group or period being assessed.
  • Expected baseline revenue without campaign: Your counterfactual estimate for the same scope and period.
  • Advertising spend: Spend included in this test.
  • Contribution margin before ad spend: Share of incremental revenue remaining after variable costs.

Inputs accept finite, nonnegative values in the displayed ranges; percentages are bounded to 0–100% (with 99.99% maximum where division by the remaining share is used), and whole-unit or month fields require integers. Currency figures are shown in USD for convenience; enter values in one consistent currency. This is a planning worksheet, not financial, legal, tax, or accounting advice.

Related calculators

Side hustle profit calculator and Marketplace fee price floor calculator.

Creator & reviewers

Creator persona

Reviewer personas

These names are pseudonymous editorial personas used to organize Northstar's work, not separate verified contributors. Reviewer assignments describe editorial responsibilities, not completed independent reviews or professional credentials. About our editorial personas.