Prebid Line Item Configuration: A Practical Guide for Publishers

Configuring line items for Prebid header bidding is more nuanced and labor-intensive than many publishers expect. The way you set up these line items directly impacts how well your ad server can compete header bidding demand with other sources—and, ultimately, how much revenue you generate.

Getting these configurations wrong often leads to lost revenue, mismatched bids, or troubleshooting headaches that can swamp your ad ops team. This guide walks publishers through the core concepts and best practices for setting up Prebid line items clearly, efficiently, and with future growth in mind.

Understanding the Role of Line Items in Prebid Header Bidding

In header bidding, Prebid.js (or Prebid Server) collects bids from multiple demand partners and pushes them into your ad server, most commonly Google Ad Manager (GAM). For your ad server to recognize and act on these bids, you need to create a tailored set of line items, each designed to match bid price points and media types. The setup isn’t just about replicating your direct sales—it’s about creating a mechanism for every potential winning bid to find a home in your ad server, ensuring you’re not leaving money on the table.

How Header Bidding Interacts with Ad Servers

When a user visits your site, Prebid runs an auction and sends the top (or all) bids and associated targeting information (like price and bidder name) to your ad server. The ad server’s line items, structured around these price buckets and key values, determine which creative and price point matches the incoming bid. If line items are missing, misconfigured, or too coarse, you can miss higher-paying bids.

Why the Right Line Item Structure Matters

Each price point in your Prebid auction should correspond to a dedicated line item. For example, with high granularity, you might have separate line items for $0.50, $0.51, $0.52, etc.—allowing precise competition between header bidding demand and other campaigns. Skimping on this granularity can cause impressions to default to lower-yielding fallback ads.

Key Decisions When Creating Prebid Line Items

The process of creating line items for Prebid is more complex than for house ads or direct-sold campaigns. Several key decisions shape the implementation, each with pros, cons, and operational trade-offs.

Choosing the Right Set of Line Items

Start by identifying your site’s needs:
– If you only run Prebid.js on web, two sets of line items suffice: one for instream video, another for banner/native/non-instream video.
– If you serve AMP or mobile app inventory, be prepared for additional sets—potentially four or more depending on ad formats (banner, video, native, rewarded).
– Keep your ad server’s line item limits in mind. Too granular a setup (i.e., thousands of price points across media types, bidders, and platforms) can hit platform constraints.

Advertiser & Order Setup Strategy

Because Prebid line items don’t have fixed advertisers behind them, create one or more generic “Prebid Advertiser” entities in your ad server. For better reporting, you may want to create a separate advertiser per bidder (e.g., “Prebid BidderA”, “Prebid BidderB”), especially if you use the ‘Send All Bids’ mode. Orders group your line items under these advertisers for easier management.

Precision in Key-Value Pairing

Your price key (hb_pb) must match the price granularity and precision set in your Prebid config. For example, with two decimals: use hb_pb=1.00, not hb_pb=1 or hb_pb=1.0. Incorrect precision leads to header bidding bids missing their target—and lost revenue.

Practical Setup: Line Item Details and Naming Conventions

A well-structured naming and grouping convention speeds up troubleshooting and future changes. It also prevents confusion as your stack grows.

Line Item Type and Priority Settings

Set line items as ‘Price Priority’ (or equivalent), enabling direct competition on price with non-Prebid demand. Give Prebid line items a priority below direct deals, but above remnant/house ads.

Group and Name Your Line Items Systematically

Best practice is to group line items by media type and, if using Send All Bids, also by bidder. For example: ‘Prebid.js – banner – BidderA – 1.25’. The line item name should include the platform, media type, (optionally) bidder, and price point. Similarly, order and creative names should convey format and purpose—e.g., creatives might be named ‘Prebid.js – banner – 1×1 – 2’.

Start/End Dates and Impression Goals

For most Prebid line items, set the start date to ‘now’ and leave the end date blank—these line items function as ongoing infrastructure, not fixed campaigns. Avoid setting impression goals, as demand is dynamically determined by bidder activity.

Examples and Common Pitfalls in Prebid Line Item Setup

It’s easy to underestimate the work involved or misconfigure elements, especially as your Prebid stack grows more complex. Concrete examples and known errors help avoid expensive mistakes.

Example: Banner and Video Line Items in GAM

Suppose you choose high granularity and ‘Send Top Bid’ for web banners. You might set up:
– ‘Prebid.js – banner – 0.00’, ‘Prebid.js – banner – 0.01’, … up to ‘Prebid.js – banner – 20.00’.
– For video, perhaps a custom range: ‘Prebid.js – video – 0.00’, ‘Prebid.js – video – 0.05’, etc.

If using ‘Send All Bids’, replicate this for every significant bidder, adjusting names to include each bidder’s code.

Common Mistakes That Can Cost Revenue

– Forgetting to set key-value precision, causing bids to miss line items
– Using too few line items (coarse granularity), resulting in under-competition
– Assigning line items the wrong priority and letting lower-value campaigns win
– Overcomplicating with more sets of line items than operationally needed, hitting ad server limits
– Confusing or inconsistent naming, making troubleshooting and inventory management harder

Rigorously document your setup to avoid these pitfalls, especially as team members or vendors change.

What this means for publishers

Line item configuration is not a ‘set and forget’ process—it’s an ongoing part of header bidding optimization. Getting granularity, naming, and grouping right will maximize each bid’s opportunity to compete, strengthening your overall yield. Poor implementation risks both revenue loss and operational headaches, particularly as inventory, partners, and formats multiply.

Practical takeaway

Any publisher serious about header bidding revenue should review their Prebid line item setup regularly. Use high enough price granularity for your main formats, but remain within your ad server’s practical limits. Name and group line items systematically for straightforward management and clear reporting.

Leverage tools (like Prebid Line Item Manager) for bulk creation and maintenance when possible, but always document your approach and rationale in an internal playbook. Finally, revisit your setup whenever you add new formats, partners, or platforms—line item structure that worked last year may be holding you back today.