How to Measure Incremental Reach Across Advertising Channels

"We ran YouTube, three OTT apps and display. How many people did we actually reach?" Add up the reach from each channel's report and you'll get a figure that's too high, sometimes by a wide margin, because the same people turn up on several channels. Incremental reach gives you the honest answer, and tells you which channel earns its place in the next plan.

What is incremental reach?

Incremental reach is the number of extra unique people a channel or campaign adds on top of the people you've already reached elsewhere. If your TV plan reaches 1.1 crore people in your target and adding CTV takes the combined total to 1.3 crore, CTV's incremental reach is 20 lakh people, even if CTV on its own reached 45 lakh.

Three related terms you'll meet in DV360:

• Unique reach: people reached at least once, counted once across their devices.
• Exclusive reach: people reached by only one part of the campaign, such as one insertion order.
• Duplicate (overlap) reach: people reached by that part and by at least one other.

For the basic formulas, see our reach and frequency calculator. This guide is about what happens when channels overlap.

Why does incremental reach matter?

Because every channel you add costs money, and not every channel adds people. A second video channel that mostly reaches people who already saw your YouTube ads adds frequency, not reach. Sometimes you want that. Often you don't.

It's also the question leadership asks when a video budget is split between TV, YouTube and OTT apps such as JioHotstar, ZEE5 and SonyLIV: what did the streaming money add to the TV plan? Our guide on how to buy and measure CTV ads in DV360 covers the buy itself. This one covers how to prove what it added.

How do you measure incremental reach inside DV360?

Inside DV360, the platform does the deduplication for you, as long as the channels you want to compare run under the same advertiser.

1. Structure for comparison. Put each channel in its own insertion order: one for YouTube, one for OTT and CTV deals, one for open web display. Overlap reports compare insertion orders, campaigns, advertisers and device types, so this structure is what makes the answer readable.
2. Run a Unique Reach Overlap report. In DV360's instant reporting templates, the Unique Reach Overlap report shows overlap reach between pairs, plus exclusive and duplicate reach for each insertion order. Our guide to creating DV360 campaign reports shows how to schedule it.
3. Read exclusive reach as each channel's incremental reach. The Exclusive Impression Reach metric for the OTT insertion order is the number of people only OTT reached. That is what OTT added on top of everything else in the campaign.
4. Track new reach over time. The Incremental Impression Reach metric counts people reached for the first time in each day, week or month of the flight. When weekly new reach flattens, extra spend is mostly buying frequency.
5. Check what your frequency cap is doing. DV360's added reach measurement estimates how many extra people the campaign reached because of its frequency cap, which moves impressions away from people who have already seen the ad. Make the report period at least as long as the cap's time period.

Pull every channel's reach over the same dates, inside the 92-day limit DV360 sets on most reach metrics. Our guide on checking reach and frequency in DV360 covers the data lag and other caveats.

A worked example inside DV360

Here's an illustrative four-week campaign for a packaged food brand. The numbers are made up to show the method.

Adding the three reach figures gives 90 lakh. The deduplicated campaign reach is 60 lakh, so 30 lakh of the "reach" in the channel reports was the same people counted again.

At first glance OTT looks expensive: about twice display's cost per exclusive person, and well above YouTube's. But those people saw a full-screen ad, often on a TV with the sound on, with completion rates that open web display rarely matches. The table tells you what each channel adds. It doesn't tell you what each person is worth. Read it alongside completion, viewability and, where you can, a brand lift study. For FMCG brands planning festive bursts, it is a useful check before deciding where the extra money goes.

How do you estimate incremental reach across TV and other platforms?

DV360 can't see your TV schedule or your social platforms, and each platform counts people its own way, so their reach figures can't simply be added or deduplicated against each other. Google's Cross-Media Reach reports, which combine TV and digital, rely on licensed TV data and aren't offered for India at present. Indian planners therefore usually estimate overlap with a formula, then check it with research when the budget justifies it.

The standard starting point is the random duplication formula, which assumes that seeing one channel doesn't change the chance of seeing the other:

Combined reach % = A + B - (A x B)

Here A and B are each channel's reach as a share of the target audience, written as decimals.

Worked example: your TV plan reaches 55% of a target audience of 2 crore adults, based on the BARC data your TV team uses. Your YouTube and CTV plan is expected to reach 30%.

• Combined reach = 0.55 + 0.30 - (0.55 x 0.30) = 0.685, or 68.5%
• Incremental reach from digital = 68.5% - 55% = 13.5 percentage points
• In people: 13.5% of 2 crore = 27 lakh
• If digital costs ₹60 lakh, cost per incremental person = ₹60,00,000 / 27,00,000 = ₹2.22, or ₹4.44 lakh per incremental reach point

Treat this as an estimate. Real overlap is rarely random. If your digital audience leans towards light TV viewers, digital's true incremental reach will be higher than the formula says. If your digital targeting mirrors the people your TV buy already reaches, it will be lower. For large budgets, a survey in your target markets asking where people saw the campaign, or a geo test, tells you which way your plan leans.

How do you use incremental reach to plan better?

1. Plan with reach curves. Each channel's reach grows quickly at first, then flattens as spend rises. Ask what the next ₹1 lakh buys in new people on each channel, not what the average rupee bought.
2. Shift money until the marginal costs are close. If the next ₹5 lakh on YouTube is forecast to add 3 lakh new people (₹1.67 each) and the next ₹5 lakh on OTT adds 4 lakh (₹1.25 each), the OTT money is working harder at the margin.
3. Cap frequency across channels. A campaign-level frequency cap in DV360 spreads impressions across more people instead of letting one channel keep hitting the same viewers.
4. Keep channels comparable. Use the same dates, the same audience definition and the same reporting window, or the comparison isn't fair.

Reach is the first link in the chain. For what that reach was worth commercially, see our guide to measuring programmatic advertising ROI.

What mistakes should you avoid?

• Adding reach from different platforms or reports together.
• Comparing channels over different date ranges, or over more than 92 days in DV360.
• Treating exclusive reach as the only measure of a channel's value.
• Using the random duplication formula as fact rather than a starting estimate.
• Splitting channels across advertisers or campaigns, which rules out a shared frequency cap and makes the comparison harder.

Next step

When we run your campaigns, our DV360 Reports Section shows unique reach and frequency alongside reports by channel and placement, so the starting numbers are there from the first week. To plan the mix before you spend, ask for a free media plan: a DV360 specialist estimates reach and cost across YouTube, OTT, display and DOOH for your budget. If you're adding streaming to a TV plan, our connected TV and OTT guide covers the apps and deal types.