Ad Inventory: Placement, Paths, Fill, and Yield
Ad inventory is the available opportunity to place an ad in a page, app, stream, or physical environment. How you sell it, floor it, and filter it changes fill, eCPM, and buyer quality. Adding an exchange does not automatically raise net revenue.
Ad inventory is the available opportunity to place advertising within a publisher, platform, app, stream, or physical environment. It can be sold directly, through private deals, or in an open auction. Its value depends on audience, context, format, viewability, supply quality, and demand. Connecting another ad exchange adds a path. It does not, by itself, raise what the publisher keeps.
IAB and PwC reported U.S. programmatic advertising revenue of $162.4 billion for full-year 2025, up 20.5% year over year, inside $294.6 billion total internet ad revenue (IAB/PwC Full Year 2025 report, April 16, 2026). That is market scale. It is not a yield forecast for a given slot.
Read inventory next to eCPM and paid media planning. Metric labels and denominators can vary by report, so define them in the worksheet: impression eCPM uses served impressions, while request eCPM uses all ad requests and exposes unfilled demand.
Inventory attributes before the sales path
Name the slot before you name the exchange.
| Attribute | What to record | Why it changes price |
|---|---|---|
| Placement | Page, app unit, stream, newsletter, screen | Buyers pay for context they can explain |
| Format | Display, native, in-stream, out-stream, rewarded | Creative type and skip rules change floors |
| Device | Mobile, desktop, CTV, app | Viewability and attention differ |
| Viewability | Google Active View follows MRC: display 50% of pixels for 1 continuous second (large ads of 242,500 pixels or more may use 30%); video 50% for 2 seconds | A served impression may still fail the viewability standard |
| Identity / audience | Direct data, contextual, none | Deal eligibility and bid density |
| Supply path | Direct, one SSP, multiple hops | Fees and ads.txt authorization |
| Quality controls | Blocks, ads.txt / sellers.json, IVT filtering | Cheap demand can lower net yield |
IAB Tech Lab ads.txt (page updated September 14, 2026) is the publisher’s public list of authorized sellers. Audit the file for missing or duplicate entries and label each authorized DIRECT or RESELLER relationship accurately.
Sales paths and the tradeoffs
| Path | What is reserved | Who may buy | Floor / price | Main tradeoff |
|---|---|---|---|---|
| Direct (IO) | Volume and dates in the contract | Named advertiser | Negotiated | Sales time; under-delivery risk sits in the IO |
| Programmatic guaranteed (PG) | Fixed impressions, dates, sizes, CPM | Named buyer who must bid when must_bid is true | Fixed CPM; Google Authorized Buyers maps OpenRTB Deal.at = 3 | Operational setup; Google Ad Manager pricing rules do not apply to Programmatic Direct |
| Preferred deal | Access, not a volume guarantee | Named buyer at a fixed or agreed price | Often fixed; still competes with other demand depending on the stack | Buyer can pass |
| Private auction / PMP | Access for listed seats; private_auction=1 can block the open auction | Listed buyers | Deal floor | Smaller demand set |
| Open auction | Nothing | Eligible exchange buyers | Publisher floor, target CPM, or optimized floor | Fill and quality vary; extra hops add fees |
In IAB OpenRTB 2.6, the Pmp object holds deals for that impression. private_auction 1 restricts bidding to the listed deals; 0 still allows other bids. A Deal’s at=3 is an agreed price on that deal, not a description of every preferred deal in the market.
Google Ad Manager dynamic allocation lets non-guaranteed demand compete with guaranteed line items on a temporary CPM so guaranteed delivery stays on pace. Open Bidding runs a unified auction among Ad Exchange, yield partners, and remnant line items. A higher bid can still lose to a reserved line item, a block, or a floor after Google’s revenue share is removed. Google’s pricing-rule example: a $1.00 bid with an 80/20 split is compared to the floor on $0.80, the publisher’s share.
Floors versus fill. A hard floor can raise eCPM and cut fill. Target CPM varies the floor per query to chase an average. Google’s published illustration: a $2.00 floor fills one query (a $2.10 bid) at $2.10 eCPM; a $2.00 target CPM fills two queries ($2.10 and $1.90) for $4.00 revenue and $2.00 eCPM. Revenue rose while eCPM fell. That is why “raise the floor” is not a net-revenue strategy by itself.
Publisher inventory worksheet
Use one row per placement. Hypothetical numbers are labeled.
| Field | Sample row (labeled) | Notes |
|---|---|---|
| Placement | ROS 300x250, article pages | Not the homepage takeover |
| Format / device | Display / mobile web | Separate desktop |
| Viewability | Active View 50%/1s | Report served impressions separately from viewable impressions |
| Floor or tCPM | $2.00 tCPM | Hard floor was $2.20 last month |
| Ad requests | 1,000,000 | Denominator for fill |
| Impressions | 720,000 | Fill = 720,000 / 1,000,000 = 72% |
| Publisher revenue | $1,440 | After exchange fee |
| Impression eCPM | $1,440 / 720,000 x 1,000 = $2.00 | Matches the tCPM in this sample |
| Request eCPM | $1,440 / 1,000,000 x 1,000 = $1.44 | Includes unfilled demand |
| Fee / rev share | 20% of bid | Floor applied after share |
| Buyer-quality controls | ads.txt relationships reviewed; block list A | DIRECT and RESELLER entries must describe the authorized relationship accurately |
If you add a second exchange and impressions stay 720,000 while fees rise, net revenue can fall even if the UI eCPM looks higher. Trace the path before you celebrate the column.
Frequently Asked Questions
What is ad inventory?
Ad inventory is the available opportunity to place advertising in a publisher environment: a page slot, app unit, stream break, newsletter, or physical screen. Its value depends on placement, format, device, audience, viewability, supply path, and which buyers are allowed to bid.
Does connecting an ad exchange increase net revenue?
No. An exchange adds a sales path. Net revenue still depends on fill, price after fees, unfilled requests, and whether low-quality demand is blocked. A higher open-auction eCPM with lower fill, extra hops, or more invalid traffic can reduce what the publisher keeps.
How should a publisher compare sales paths?
Compare direct, programmatic guaranteed, preferred or private marketplace, and open auction on reservation, who may bid, floor behavior, and operational cost. Programmatic guaranteed reserves a fixed volume at a fixed CPM. Open auction does not. Pricing rules often do not apply to programmatic direct.
What belongs on an inventory worksheet?
For each placement record format, device, viewability standard, floor or target CPM, fill, fee or revenue share, eCPM, and buyer-quality controls. Use the same denominator when you compare sources. Impression eCPM and request eCPM answer different questions.
Sources
- IAB/PwC, Internet Advertising Revenue Report: Full Year 2025, dated April 16, 2026, accessed September 20, 2026. Market context only.
- IAB/PwC, Internet Advertising Revenue Report PDF, dated April 2026, accessed September 20, 2026. Market context only.
- IAB Tech Lab, OpenRTB 2.6, accessed September 20, 2026.
- IAB Tech Lab, ads.txt, page updated September 14, 2026, accessed September 20, 2026.
- Google Ad Manager Help, Pricing rules, accessed September 20, 2026.
- Google Ad Manager Help, Understand target CPM, accessed September 20, 2026.
- Google Ad Manager Help, Ad competition with dynamic allocation, accessed September 20, 2026.
- Google Authorized Buyers Help, Real-time Bidding differences for Programmatic Guaranteed Deals, accessed September 20, 2026.
- Google Ad Manager Help, Find opportunities to optimize revenue, accessed September 20, 2026.
- Google Ads Help, About Active View, accessed September 20, 2026.
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