Supply cost is the money a demand-side platform (DSP) spends on the advertising inventory a campaign actually wins: the cleared price of each impression, summed across the campaign. It exists as a separate line because programmatic buying bundles several costs into one budget. The publisher's media, the DSP's technology fee, audience and data charges, measurement vendors and, increasingly, the agency's own fee all draw on the same pool of money. Supply cost isolates the first of those. Amazon's advertising support documentation puts it in a single sentence, as quoted by PPC Land on November 12, 2026: "Supply cost is the cost of the media the ads run on."

The term matters now because Amazon has made it the base for agency fees inside its DSP, and because the gap between supply cost and publisher revenue remains poorly visible.

How supply cost is calculated

The arithmetic starts at the auction. When a publisher's supply-side platform (SSP) sends a bid request and a DSP wins it, the impression clears at a price expressed as a CPM, or cost per thousand impressions. Supply cost for a line item is the sum of those cleared prices: CPM multiplied by impressions, divided by 1,000. A campaign that wins 2 million impressions at an average clearing price of $5 CPM records $10,000 in supply cost.

Everything else is layered on top. Amazon's pricing transparency guide, published under the European Union's Digital Markets Act (DMA), sets out two formulas, according to Amazon Ads. Total advertiser cost equals supply cost plus demand-side fees plus any other amounts payable to Amazon. Publisher earnings equal supply cost minus supply-side fees. The demand-side fees are themselves a sum: audience fee, technology fee, third-party pre-bid targeting fees, third-party audience fees and any managed service fee. Amazon describes the technology fee, also called the platform or console fee, as a percentage of media cost, set at entity level and disclosed when a campaign is created.

Supply cost is the hinge between buyer and seller: the floor of the advertiser's bill and the ceiling of the publisher's revenue.

Reporting tools expose the same split. Supermetrics, which pulls Amazon DSP data into dashboards, defines the field as "the total amount of money spent on media supply" and describes the console fee as "the technology fee applied to the media supply costs", according to its documentation updated March 5, 2026. Amazon's August 2022 reporting guide calculates cost per purchase and similar efficiency metrics against total cost, so they already include platform fees.

Adbrew, a third-party reseller, illustrates the layers in an example July 2026 invoice: $152.03 in supply cost, $11.73 in platform fee and $136.24 in audience fees, for a total of $300.00. In that example, media made up barely half of the bill. Adbrew lists the platform fee at 8% of supply cost in the United States and 10% in the EU, India and Australia, according to its help centre. Amazon does not publish those rates on its own pricing page.

Agency fees built on supply cost

On November 11, 2026, Amazon updated its support documentation to describe agency fees set from a manager account, in open beta across all marketplaces for display, video and audio. Four of the five calculation methods use supply cost as the base:

  • % of Supply Cost (markup)
  • % of Supply Cost + Amazon Audience Fee (markup)
  • % of Supply Cost + Total Audience Fee (markup)
  • % of Supply Cost + Total Audience Fee + 3P Prebid (markup)
  • % of Budget (margin)

A 3.5% markup on $10,000 of supply cost produces a $350 fee, bringing the total to $10,350. The fee then equals 3.38% of the combined spend, not 3.5%, a difference that compounds across large budgets. Fees can be set at account, campaign or ad group level, with the most specific winning. Amazon does not bill the agency fee itself. It appears in reports and reserves part of the budget. The legacy campaign-level fee can be added until January 31, 2027 and will be removed by the end of March 2027, according to the same PPC Land report, which noted that "if supply cost moves, every markup calculated on supply cost moves with it."

Origin and evolution

No single body coined the term, which emerged from DSP reporting. The concept is older than the phrase. In its May 2017 programmatic study, the Association of National Advertisers (ANA) found that inventory accounted for $3.30 of a $4.80 all-in display CPM, with $1.49 in demand-side fees: 72 cents of each dollar reached inventory.

The UK followed. A May 2020 study by the Incorporated Society of British Advertisers (ISBA) and PwC traced spend from advertisers to publishers and found that publishers received 51% of the original budget, with 15% classed as an "unknown delta" that could not be attributed. The Competition and Markets Authority (CMA), in an appendix on fees in the ad tech stack published with its July 2020 final report on online platforms and digital advertising, defined SSP fees as those "associated with the sale of digital advertising on behalf of publishers" according to the CMA. A second ISBA and PwC study, published January 18, 2023, restated the 2020 numbers to 57% and 17%, and cut the unknown delta to 3%, or under 1% for private marketplace deals. ISBA and PwC defined that delta as discrepancies in media cost "between amounts recorded as leaving the DSP and entering the SSP", in other words, in supply cost itself.

Adalytics, in a study reported in April 2022, examined the supply side directly. Most SSPs charged a median supply fee of about 20% of the clearing price, two exceeded 50%, and one SSP charged a single publisher between 7% and 42%, according to Adalytics. The ANA's full transparency report in December 2023 found 29% of DSP spend went to DSP and SSP fees combined, according to Marketing Brew.

Why it matters to marketers

Supply cost determines how much of a budget can buy reach at all. The ANA's Programmatic Transparency Benchmark put TrueAdSpend at 41% in Q1 2025, with 26.1% consumed by DSP, data and SSP costs, figures IAB Spain cited in its first SSP guide in April 2026. The guide put publisher delivery at 70% to 80% on direct SSP paths and 40% to 50% on indirect ones.

Fee pressure on the DSP side has moved money toward supply cost. Amazon's DSP fee was reported at about 1%, against 12% to 15% for The Trade Desk according to a Needham estimate cited in August 2025. By November 2025, Amazon was charging nothing on programmatic guaranteed deals for its own media and 1% on the open web. Jeff Green, chief executive of The Trade Desk, gave the arithmetic on August 6, 2026: at an 8% fee a dollar buys $1.08 of media, at 4% it buys $1.04. Those reported rates conflict with the 8% and 10% platform fees on Adbrew's published schedule, and Amazon has not reconciled them publicly.

Limitations and disputes

Supply cost is not what a publisher earns. The SSP fee comes out of it, and so do any reseller hops. On Adalytics' median, $10,000 in supply cost becomes $8,000 for the publisher before ad serving fees. The DSP cannot always see that deduction, which is why the unknown delta lived inside it for years.

Definitions also drift. Supermetrics describes Amazon's total cost as excluding third-party fees paid by the agency. Adbrew states total cost as supply cost plus demand-side fees. Amazon's DMA formula adds "other amounts payable to Amazon". A report comparing cost per acquisition across vendors can therefore compare different denominators.

Markups based on supply cost create their own incentive. An agency earning a percentage of supply cost earns more when media prices rise, a structural tension the take rate debate has circled since the 15% agency commission. Principal-based buying, where agencies resell inventory at an undisclosed price, makes supply cost harder still to read, since the advertiser sees the agency's price rather than the auction clearing price.

Supply fee is the SSP's cut of the clearing price, deducted on the sell side. Supply cost is the gross media spend from which that fee is taken.

Media cost is often used interchangeably with supply cost, including by Adbrew and Amazon's own fee descriptions. Some platforms use media cost to include certain data or verification charges, so the two can diverge.

Working media is the share of total spend that reaches the publisher or the consumer, depending on the study. It sits below supply cost.

Total cost adds demand-side fees, and sometimes agency fees, to supply cost. It is the figure most Amazon efficiency metrics divide by.

Recent developments

Sell-side fees are also shifting. PubMatic's supply policy, effective April 16, 2026, added an excess inventory fee of $0.001 CPM for publishers sending impressions beyond daily caps. Viant extended Direct Access on September 24, 2026, with no set-up or running charge for buyer or seller on the route, though platform, ad serving and data charges still apply. The Trade Desk's OpenPath charges publishers a flat 4.5% fee.

Amazon, meanwhile, said on July 21, 2026 that its Certified Supply Exchange program now covers Magnite, PubMatic, Index Exchange, OpenX and Microsoft Monetize, with more than 375 certified deals across 28 sports since December 2025, according to Amazon Ads, though the post did not address fees. The November 11 agency fee update makes supply cost the default unit of account for Amazon agency fees.

Timeline

  • 1993 - France's Loi Sapin requires agencies to act as transparent agents for advertisers.
  • May 18, 2017 - ANA programmatic study finds inventory accounts for 72 cents of each programmatic display dollar.
  • May 2020 - ISBA and PwC find publishers receive 51% of spend, with a 15% unknown delta.
  • July 1, 2020 - CMA final report on online platforms and digital advertising publishes its appendix on ad tech fees.
  • April 2022 - Adalytics reports a median SSP supply fee of about 20%, with outliers above 50%.
  • August 2022 - Amazon's self-service reporting guide bases cost metrics on total cost.
  • January 18, 2023 - ISBA and PwC study II restates figures to 57% and 17%, unknown delta 3%.
  • December 2023 - ANA full transparency report finds 29% of DSP spend goes to DSP and SSP fees.
  • 2024 - Amazon Certified Supply Exchange program begins, according to Amazon.
  • Q1 2025 - ANA benchmark puts TrueAdSpend at 41%, transaction costs at 26.1%.
  • November 2025 - Amazon reported charging 0% on owned-media programmatic guaranteed deals, 1% on open web.
  • April 16, 2026 - PubMatic supply policy and excess inventory fee take effect.
  • July 21, 2026 - Amazon names five certified SSPs in its Certified Supply Exchange.
  • September 24, 2026 - Viant extends fee-free Direct Access deal route.
  • November 11, 2026 - Amazon documents manager-account agency fees, four of five based on supply cost.
  • January 31, 2027 - Last date to add Amazon's legacy campaign-level agency fee.
  • End of March 2027 - Legacy agency fee setting removed.

Summary

Who: DSPs such as Amazon's report supply cost to advertisers and agencies. SSPs deduct their fees from it before paying publishers. Agencies on Amazon can now calculate their fees on it.

What: Supply cost is the total cleared price of the impressions a campaign wins, before technology, audience, third-party and agency fees.

When: The underlying split has been measured since the ANA's 2017 study. Amazon made supply cost the main base for agency fees on November 11, 2026, with the legacy setting retired by March 2027.

Where: In DSP reports and invoices, in Amazon's DMA pricing formulas, and in supply chain audits by ISBA, PwC, the ANA and the CMA.

Why: Separating media from fees shows how much of a budget buys inventory, and how much of that reaches publishers after SSP deductions.