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CalcFuel
Paid Advertising· 10 min read · 9 May 2026

How to Calculate Ad Spend ROI: A Complete Guide

Most advertisers track ROAS. Fewer track actual ROI. The formula, three worked examples, and when to cut a campaign.

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ROAS vs ROI: What Is the Difference?

ROAS = Revenue from Ads divided by Ad Spend. Revenue per dollar of ad spend. Platform default metric.

ROI = ((Revenue minus Total Cost) divided by Total Cost) times 100. Actual profit after all costs including COGS.

A 4x ROAS campaign can still be unprofitable. A 30 percent margin retailer needs 3.3x ROAS just to break even on ad spend before other operating costs.

The Ad Spend ROI Formula

Ad Spend ROI percent = ((Gross Profit from Ads minus Ad Spend) divided by Ad Spend) times 100

Where: Gross Profit = Revenue times Gross Margin percent

3 Worked Examples

Example 1: Google Search Ads (eCommerce)

Ad spend: $2,000. Revenue: $8,000. 45 percent gross margin. Gross profit = $3,600. ROI = 80 percent. ROAS = 4x. Profitable but margin-constrained.

Example 2: Facebook Retargeting

Ad spend: $500. Revenue: $2,500. 45 percent gross margin. Gross profit = $1,125. ROI = 125 percent. ROAS = 5x. Retargeting captures pre-existing intent.

Example 3: LinkedIn B2B Ads

Monthly spend: $3,000. 15 leads at 20 percent close = 3 clients at $5,000 ACV = $15,000. 70 percent GM. Gross profit = $10,500. ROI = 250 percent. High CPL justified by high CLV.

Attribution Models and How They Affect ROI

ModelHow It WorksBest For
Last-click100 percent credit to final touchpointSimple funnels
First-click100 percent credit to first touchpointAwareness campaigns
LinearEqual credit across all touchpointsMulti-touch B2B journeys
Data-drivenML assigns credit by conversion patternsHigh-volume Google Ads accounts

Last-click (platform default) overstates bottom-of-funnel channels. Use consistent attribution when comparing ROI across channels.

When to Kill a Campaign

  1. Negative ROI after 3-5x target CPA spend. The data is clear — cut it.
  2. Payback period exceeds cash flow capacity. ROI-positive on paper but cash-negative for months is unsustainable.
  3. Opportunity cost too high. Redeploy if same budget delivers 3x the ROI elsewhere.
  4. Volume ceiling reached. More spend only increases CPCs — find a new channel.

What Is a Good Ad Spend ROI?

ChannelTypical ROI Range
Google Search100-300 percent
Google Shopping80-250 percent
Facebook / Instagram50-200 percent
LinkedIn Ads50-300 percent (high CPL, high CLV in B2B)

For paid channels, ROI above 100 percent is the minimum viable threshold. Below that, you are destroying value.

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