Incremental sales calculator

Are my ads creating sales, or taking credit? Conversion lift: the sales your ads added, measured against a group that did not see them, and the ROAS on those sales alone.

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Your numbers

We have filled in typical numbers. Change any of them to yours.

How it is calculated

Are my ads creating sales, or taking credit?

YES

Full breakdown

Three fixes for your numbers

  • Cut retargeting that buys sales you'd get anyway
  • Move budget to prospecting with real lift
  • Re-test every quarter

See the full breakdownThe numbers behind your answer and three fixes, also sent to your WhatsApp.

How it is calculated

Worked through with the typical numbers already in the calculator.

What you get

  • Conversion lift from a holdout test
  • Purchases your ads actually created
  • Incremental ROAS next to platform ROAS
StepFormulaResult
Test group conversion rate2,400 ÷ 500,0000.48%
Holdout conversion rate1,700 ÷ 500,0000.34%
Extra purchases from ads2,400 − 0.34% × 500,000700
Incremental ROAS700 × ₹1200 ÷ ₹600,0001.40

What a good number looks like

This is our rule of thumb for reading results. A test needs enough purchases in both groups to be trusted, so small tests are read with care.

How we read conversion lift
How we read conversion lift
Under 5%Ads add little. Most sales would happen anyway.
5 to 20%The ads add something, but not much. Check incremental ROAS against break-even.
Over 20%Ads create a meaningful share of sales.

This page was updated in October 2026 and reviewed by our senior marketing team.

Mistakes that make this number wrong

We see these in most accounts we audit.

Treating attributed sales as incremental

Platforms count sales the ad touched. Some would have happened anyway.

Holdout groups too small

A tiny holdout gives a result that could be chance. Size the test before it starts.

Changing things mid-test

New offers, prices or campaigns during a test muddy the result.

Reading revenue, not margin

Incremental sales only matter if they make money after every cost.

Definitions and questions

What is a conversion lift test?

Meta or Google splits your audience. One group sees your ads, a holdout group does not. The difference is what ads created.

What is incremental ROAS?

Incremental ROAS is the revenue from the extra purchases your ads caused, divided by ad spend. It is usually lower than platform ROAS, and it is the number that matters.

Why is it lower than platform ROAS?

Platforms also count people who would have bought anyway, so their number includes sales the ads did not create.

What is a holdout group?

People kept from seeing your ads on purpose. Comparing their purchases with the test group shows what the ads added.

What numbers do I need?

You need the size of your test and holdout groups, purchases in each, your average order value and the ad spend in the test.

Where do I get these numbers?

From a Meta or Google conversion lift study, or from a geo test where ads run in some regions and not in others.

What is a good conversion lift?

As a rule of thumb, under 5% means ads add little, 5 to 20% is real but modest, and over 20% means ads create a meaningful share of sales.

What should I do with the result?

Move budget towards channels and audiences with the highest incremental ROAS, and cut spend that only takes credit.

Which campaigns should I test first?

Test retargeting and brand search first, because they most often take credit for sales that would have happened anyway.

How big should the holdout group be?

Big enough for the difference to be clear. Platform lift studies size the groups for you, and we size geo tests before you commit.

Can I run a lift test without a platform study?

Yes, with a geo test: ads run in some regions and not in others, and the difference in sales shows what the ads added.

60 seconds

Are we a great fit?

Five questions, no email needed. You get an honest answer on screen.

Incremental sales calculator: Test group conversion rate 2,400 ÷ 500,000; Holdout conversion rate 1,700 ÷ 500,000; Extra purchases from ads 2,400 − 0.34% × 500,000; Incremental ROAS 700 × ₹1200 ÷ ₹600,000
Incremental sales calculator, at a glance

Want us to run these on your real numbers?

Tell us about your brand. We read your accounts before the call, so it is about your numbers.

  • Free growth audit, yours to keep
  • ROAS and profit read for every channel
  • WhatsApp reply within one working day

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