Sainsbury Cross-Channel Net Reach Calculator
Eliminate the double-counting illusion. Calculate true unduplicated net reach and cross-platform audience duplication when running coordinated campaigns across Meta Ads, Google Ads, YouTube, and other ad networks.
🧮 Interactive Sainsbury Reach Calculator
Adjust reach percentages below to simulate your unduplicated reach across digital ad networks.
The Sainsbury Math: How It Works
When measuring cross-channel ad campaigns across platforms like Meta, Google Ads, and TikTok, ad managers report their own reach in isolation. If Meta reports 40% reach and Google reports 30% reach, adding them together (40% + 30% = 70%) calculates Max Reach—a theoretical ceiling that assumes zero people saw both ads.
The Sainsbury Random Duplication Method flips the arithmetic by calculating the probability that a person was exposed to neither channel:
P(Unreached) = (1 - R₁) × (1 - R₂) × ... × (1 - Rₖ)
Net Reach (%) = 1 - P(Unreached)
Cross-Channel Duplication Benchmarks
The table below illustrates realistic multi-channel campaign scenarios and how audience overlap scales as you introduce additional platforms:
| Campaign Channel Mix | Gross Sum (Max Reach) | Audience Duplication | True Net Reach |
|---|---|---|---|
| Meta + Google Search (40% + 30%) | 70.0% | 12.0% | 58.0% |
| Meta + Google + YouTube (45% + 35% + 25%) | 105.0% | 31.8% | 73.2% |
| Meta + TikTok + YouTube (30% + 25% + 20%) | 75.0% | 17.0% | 58.0% |
| 4-Channel Omni Mix (Meta, Google, YT, CTV) | 135.0% | 55.4% | 79.6% |
For complete mathematical proofs, the 5th-grade paint-splash mental model, and average frequency formulas, read our cornerstone guide: The Sainsbury Method in Media Planning: How to Calculate Unduplicated Net Reach.
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