---
title: "What a fidelity score measures | AdBuyMCP"
description: "A fidelity score answers one question: how much of your audience definition survived the translation into a channel's native targeting."
url: "https://adbuymcp.com/guides/what-a-fidelity-score-is"
---

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Guide · knowing what you bought

# What a fidelity score measures

The score shows how much of the audience you described survives translation into each channel's targeting.

A fidelity score is a number out of 100 attached to a compiled channel plan, answering one question: how much of your audience definition survived the translation into the targeting vocabulary this channel actually accepts. It measures the targeting alone, and says nothing about media quality or how a campaign will perform. In AdBuyMCP's channel catalogue the scores run from 85 on CTV, where consent-chained business segments can carry a person-level claim, down to 40 on cinema, the lowest fixed score, where the buy is a projection from venue catchments; a thin brief can take paid social to 38. Each score carries a grade naming what is really being addressed (person, household, content, geo-cohort or venue) and a written rationale from the compiler that produced it. AdBuyMCP's awareness plans are priced on the size of your market and how often it should see you, and each plan channel's page states its limit in plain words.

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By [James Rooney](https://adbuymcp.com/about) Updated 29 October 2026

- **Range published**: 85 down to 38
- **Grades**: 5 levels from person to venue
- **Fixed scores**: 4 of 7 catalogue channels
- **Length**: 10 min read

Sources

1 linked and dated

On this page

[What to remember](https://adbuymcp.com/guides/what-a-fidelity-score-is#takeaways)

[What the score measures](https://adbuymcp.com/guides/what-a-fidelity-score-is#what-the-score-measures)

[The grade says what is being addressed](https://adbuymcp.com/guides/what-a-fidelity-score-is#the-grade-says-what-is-being-addressed)

[Every published band, channel by channel](https://adbuymcp.com/guides/what-a-fidelity-score-is#every-published-band-channel-by-channel)

[How the number is produced](https://adbuymcp.com/guides/what-a-fidelity-score-is#how-the-number-is-produced)

[What moves the score](https://adbuymcp.com/guides/what-a-fidelity-score-is#what-moves-the-score)

[Each score comes with a lawful-basis manifest](https://adbuymcp.com/guides/what-a-fidelity-score-is#each-score-comes-with-a-lawful-basis-manifest)

[A low score can still be the right buy](https://adbuymcp.com/guides/what-a-fidelity-score-is#a-low-score-can-still-be-the-right-buy)

[How to use the number as a buyer](https://adbuymcp.com/guides/what-a-fidelity-score-is#how-to-use-the-number-as-a-buyer)

[Limits that apply](https://adbuymcp.com/guides/what-a-fidelity-score-is#limits)

[Where this came from](https://adbuymcp.com/guides/what-a-fidelity-score-is#sources)

[Questions](https://adbuymcp.com/guides/what-a-fidelity-score-is#questions)

Who this is for

Anyone comparing multi-channel media proposals and trying to work out which of the targeting claims in them are real, and anyone who has to defend a channel mix to somebody more sceptical than they are.

Key points

## Remember these points if you read nothing else

These are the points most likely to change your decision, and the full guide follows below.

1. 01
   The score measures the distance between what you asked for and what the channel can express. It says nothing about whether the media is any good.
2. 02
   Grade and score are two axes. On paid search the same content grade runs from 82 down to 45, depending on whether your brief carried intent or only a label.
3. 03
   Four of the channels in AdBuyMCP's catalogue have a single fixed band, so no brief improves them. Knowing which is which stops a lot of wasted effort.
4. 04
   The language model never emits a vendor segment identifier. Deterministic registry tables do, which is why a compiled plan can be audited.
5. 05
   A score of 40 can be the right buy. A full screen with the lights down has an attention profile nothing else on the list matches, and the score is not an argument against it.

01

## What the score measures

Ask for London-based technology decision makers and every channel will sell you something. What none of them will tell you unprompted is how far the thing they sold you is from the thing you asked for. On connected TV it is a set of consent-chained business intent segments delivered against streaming households, which is a good proxy. On a billboard it is a rail station at commuter hours, which is a statement about a place rather than about a person. Both are legitimate buys. They are not the same buy, and no invoice tells you which one you got.

A fidelity score is the answer to that single question, computed at the moment the audience is compiled rather than asserted afterwards. AdBuyMCP's compilers return one with every channel plan they produce, and every band is published, with the condition behind it, in the fidelity dataset.

The number measures the targeting and nothing else. It says nothing about the inventory, the viewability or the attention, and it makes no claim about reach or outcomes. It is also a property of the channel's vocabulary, so a competitor buying the same channel faces the same ceiling whether or not they publish it.

02

## The grade says what is being addressed

Each score carries a grade naming what is really being addressed. The grades run from closest to the individual to furthest from it, and they are the part of the model that survives translation into a slide.

- **Person**: The targeting rests on a segment whose provider asserts a consent chain to individuals. In AdBuyMCP's catalogue only CTV reaches it, at 85, and only where the match is strong.
- **Household**: The targeting selects a household by its address. Addressable TV is fixed at 55; CTV drops to household at 65 or 60 when segments match weakly or not at all.
- **Content**: You are buying what somebody is reading, listening to or searching for. Search runs 82, 68 or 45 on this grade depending on the brief; social runs 62, 48 or 38; audio is fixed at 65.
- **Geo-cohort**: A property of a place and a time rather than of a person. Digital out-of-home is fixed at 50, because a screen can only be somewhere a cohort is known to be.
- **Venue**: A projection from a venue's catchment. Cinema is fixed at 40, and the compiler says so in its own rationale.

03

## Every published band, channel by channel

These are all the bands the catalogue's compilers return, each channel's best band first, with what a brief has to supply to reach each one. Four channels return a single band whatever the brief says. The other three move with it.

- **CTV & streaming TV**: 85, person: At least one marketplace segment matches the persona strongly. 65, household: Segments matched only weakly, so the plan comes flagged for a person to review. 60, household: Nothing in the catalogue matched the persona's terms.
- **Podcast & digital audio**: 65, content: Every audio plan lands in this band, because the audio targeting vocabulary goes no further.
- **Addressable & linear TV**: 55, household: Every addressable TV plan lands in this band, because the channel targets households.
- **Cinema**: 40, venue: Every cinema plan lands in this band, because the channel targets venues and films.
- **Digital out-of-home**: 50, geo-cohort: Every DOOH plan lands in this band however well the persona matched, because 50 is the best claim the vocabulary carries. The ranking half of that rationale describes the intended design; the compiler returns an empty list today.
- **Paid search**: 82, content: The brief names the search topics your buyers actually type. 68, content: The brief names interests rather than intent. 45, content: The brief is a persona label and nothing else.
- **Paid social**: 62, content: The brief supplies interest terms. 48, content: Demographics but no interests. 38, content: Neither interests nor demographics.

- [Every fidelity band with conditions and a CSV](https://adbuymcp.com/data/fidelity-bands)

04

## How the number is produced

Each channel has a compiler, and a compiler is a pure function: persona plus registry in, targeting specification plus fidelity object plus lawful-basis manifest out. Same input, same output, every time, which is what makes a plan auditable and a disagreement about it resolvable.

The compiler matches your persona's own terms against the keywords on each catalogue entry and takes the top few detailed matches: four attributes on addressable TV, three packs on cinema, four venue types and three audience segments on out-of-home. Match confidence is not decoration: on connected TV a person-level grade requires at least one match at or above the strong-match threshold, and a set of weak matches produces a household grade and a flag for human review rather than a promotion.

The important structural rule is what the language model is not allowed to do. It extracts semantics from your brief (geography, seniority, sector, intent topics, exclusions) and it never emits a vendor segment identifier. Deterministic registry tables do that. A model can hallucinate a segment id that looks exactly like a real one; a lookup table cannot return an entry that is not in it, and that is the difference between a plan you can audit and a plan you have to trust.

05

## What moves the score

Three things move a score, and the compiler names each one in its rationale or in a warning rather than absorbing it.

The first is the quality of the brief, on the three channels where it matters. Paid search compiles to 82 from buyer-authored intent topics, 68 from interests, and 45 from a persona label with no product context. At 45 the rationale says exactly what is missing, which is product and offer context before the keyword plan is activation-ready. On the four fixed channels no amount of audience detail changes the score at all, and pretending otherwise would waste a buyer's afternoon.

The second is geography we cannot map. Naming a city with no entry in the geography table costs fifteen points, floored so a score cannot fall below ten, and the rationale names the city that caused it. The alternative, silently dropping an unmapped city and reporting the same score, is the failure mode that makes a plan look complete and deliver nationally.

The third is an exclusion the channel cannot express. Where your brief excludes something and the channel has no native negative targeting, the compiler drops the overlapping segments and raises a warning naming the exclusion and what it dropped, rather than quietly buying an audience you asked it not to.

06

## Each score comes with a lawful-basis manifest

A fidelity score answers how close the targeting got. A lawful-basis manifest answers what made it lawful, and the two are produced by the same compilation pass because they are the same question asked from two directions.

Every segment that enters a plan goes through a policy gate first. A consent-chained source is allowed with a condition attached: the supply chain must be consent-attested and the vendor attestation verified on connection. A legitimate-interest source is allowed with the condition that a legitimate interests assessment, the test the ICO describes for that basis, is on file for it. Aggregate and buyer-authored inputs (cinema audience packs, out-of-home venue types, postcode polygons, your own search terms) carry no personal data and are allowed outright, which is why cinema's manifest is the shortest in the catalogue.

The manifest also carries a baseline entry for the channel itself and for the geographic scope, so the answer to "where did this audience come from?" is a document attached to the plan rather than a conversation weeks later. It is a record of what the compiler acted on. It is not a legal opinion and it does not replace your own assessment.

Source: [Information Commissioner's Office, When can we rely on legitimate interests?](https://ico.org.uk/for-organisations/uk-gdpr-guidance-and-resources/lawful-basis/legitimate-interests/when-can-we-rely-on-legitimate-interests/) (regulator).

- [What a DPO asks about this](https://adbuymcp.com/security)

07

## A low score can still be the right buy

Cinema scores 40 because it targets by venue, and it can still be the right buy: a full screen with the lights down has an attention profile nothing else on the list matches. The score measures only the targeting, so it tells you what claim a channel can support afterwards and leaves the question of whether to buy it to you.

The same holds for out-of-home. A billboard cannot know who is walking past, so its score describes a place and a time, and a buyer who wants to reach a business district at commuting hours is buying exactly what the score says.

08

## How to use the number as a buyer

Read the grade before the score. Scores of 68 at content grade and 65 at household grade are close as numbers and different as buys, and the grade tells you which claim the campaign can support afterwards.

Then check whether the band is fixed, as it is on four of the catalogue's channels. If it is, your effort is better spent on the brief for the channels where it moves (search, CTV and paid social) than on trying to improve a number that is a constant.

Then read the rationale and the warnings, which is where the compiler explains itself. An unmapped city, a dropped exclusion, a weak segment match flagged for review: each of those is a specific thing you can fix by editing the brief, and each of them is invisible on a plan that reports a single blended figure.

Finally, use the score to size the argument rather than to rank the channels. The right question is not "which channel scores highest?" but "is this score good enough for the money I am about to put behind it?" Only you can answer that.

- [Every fidelity band, with a CSV](https://adbuymcp.com/data/fidelity-bands)
- [What the weekly report shows](https://adbuymcp.com/measurement)

Type your company website or work email to see who we think buys from you, how big your market is and what it costs at 3, 5 or 12 times a week.

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Free, with no card.

Limits

## These limits apply to everything above

A fidelity score measures only how well your audience translated into each channel's targeting. It does not measure media quality, viewability, brand safety or fraud, none of which we have integrated at all. It is not evidence about outcomes: the scores are properties of the compilers, and no AdBuyMCP campaign has yet run live or produced a causal result. Segment catalogues today are sandbox-scale slices of each taxonomy loaded into the same shapes production would use, so a match against them demonstrates the method rather than the full inventory of a vendor's marketplace. And a person-level grade means the segment provider asserts a consent chain, not that AdBuyMCP has audited every link in it.

A 30-minute call with the founder will tell you whether any of these limits matters for your market.

[Book a 30-minute call with the founder](https://adbuymcp.com/contact#book)

Where this came from

## Every figure above comes from one of these

Outside figures link to the page that published them, with the day each was opened. Product facts name the part of AdBuyMCP they come from.

### Published sources

1. 01
   [Information Commissioner's Office, When can we rely on legitimate interests?](https://ico.org.uk/for-organisations/uk-gdpr-guidance-and-resources/lawful-basis/legitimate-interests/when-can-we-rely-on-legitimate-interests/)
   Regulator · opened 24 September 2026

### AdBuyMCP’s own product facts

- 01 AdBuyMCP's channel compilers: every catalogue channel's scores, the strong-match threshold, the fifteen-point geography penalty and the exclusion warnings
- 02 AdBuyMCP's policy engine: the three policy verdicts and the conditions attached to consent-chained and legitimate-interest sources
- 03 AdBuyMCP's segment catalogues: the lists an audience is matched against, which the product itself labels as sandbox-scale slices
- 04 This site's channel catalogue: every published band, grade and rationale, quoted from the compilers

Read next

## These pages pick up where this guide stops

Each one goes further into a part of this guide.

### [Every fidelity band](https://adbuymcp.com/data/fidelity-bands)

The published dataset, from 85 on CTV to 38 on a thin paid-social brief, with the condition behind each band and a CSV.

### [How UK media buying works for B2B](https://adbuymcp.com/guides/uk-media-buying-for-b2b-marketers)

Why most B2B buyers have vendors in mind before they search, and how each channel is aimed at a market that is not looking yet.

### [Measurement](https://adbuymcp.com/measurement)

What the weekly report shows for each channel, and when a geo-lift test can say more.

The other 19 guides

- [Most B2B buyers have vendors in mind before they search](https://adbuymcp.com/guides/uk-media-buying-for-b2b-marketers)
- [Why cross-channel frequency capping rarely happens](https://adbuymcp.com/guides/frequency-capping-across-channels)
- [Buying UK DOOH without a movement-data licence](https://adbuymcp.com/guides/buying-uk-dooh-without-movement-data)
- [How to buy podcast ads in the UK](https://adbuymcp.com/guides/how-to-buy-podcast-ads-in-the-uk)
- [The minimum budget for a startup to test TV advertising in the UK](https://adbuymcp.com/guides/minimum-budget-to-test-tv-advertising)
- [How to read a media plan](https://adbuymcp.com/guides/how-to-read-a-media-plan)
- [What a DSP does and when you need one](https://adbuymcp.com/guides/what-is-a-dsp-and-do-you-need-one)
- [How UK addressable TV targeting actually works](https://adbuymcp.com/guides/how-uk-addressable-tv-targeting-works)
- [How Sky AdSmart works](https://adbuymcp.com/guides/sky-adsmart-explained)
- [How UK cinema advertising is booked](https://adbuymcp.com/guides/how-uk-cinema-advertising-is-booked)
- [Choosing between cinema and CTV](https://adbuymcp.com/guides/choosing-between-cinema-and-ctv)
- [Designing a geo-lift test that can actually be powered](https://adbuymcp.com/guides/designing-a-geo-lift-test)
- [Incrementality testing on a small budget: a worked power table](https://adbuymcp.com/guides/incrementality-testing-on-a-small-budget)
- [Why most incrementality tests are invalid](https://adbuymcp.com/guides/why-most-incrementality-tests-are-invalid)
- [First-party data in UK media buying](https://adbuymcp.com/guides/first-party-data-in-uk-media-buying)
- [What Clearcast and the CAA actually check](https://adbuymcp.com/guides/what-clearcast-and-the-caa-actually-check)
- [Running paid media from an AI agent without losing control](https://adbuymcp.com/guides/running-paid-media-from-an-ai-agent)
- [MCP for marketers: what the protocol actually changes](https://adbuymcp.com/guides/mcp-for-marketers)
- [The ad platforms' own MCP servers, and planning one budget across them](https://adbuymcp.com/guides/ad-platform-mcp-servers-and-cross-channel-planning)

Bring your market

## We'll price an awareness plan for your own market.

In a 30-minute call with the founder, we work out how big your market is, price 3, 5 and 12 times a week, and talk through how we'd balance the four channels for your market.

[Get my plan and price](https://adbuymcp.com/start) [Book a 30-minute call with the founder](https://adbuymcp.com/contact#book)

Free, with no card.

Talk your market and your plan through with James Rooney, who built AdBuyMCP and wrote its code.

## Questions this guide gets asked

### Is a fidelity score an industry standard?

No. It is this platform's own construct, computed by its own compilers, and there is no external body defining or auditing it. What makes it useful is not authority but consistency: the same function produces it for every channel and every brief, the rationale is published beside the number, and the scores are comparable across the catalogue's channels because they answer the same question.

### Could you not just raise the scores?

Only by changing the compilers, because each score is set in the compiler for its channel and every brief runs through the same one. The low scores (40 on cinema, 50 on out-of-home, 55 on addressable TV) are published in the same dataset as the 85 on CTV, so every channel is read on one scale.

### Does a higher fidelity score mean better performance?

No, and conflating the two is the misreading most likely to cost money. Fidelity measures how close the targeting is to your description of the audience. Performance depends on the creative, the offer, the medium's attention profile and the competitive context, none of which the score touches. Cinema has the lowest fixed score and can outperform a precisely targeted display campaign on the things cinema is good at.