The actual cost of an online advertising campaign is not limited to the CPC or CPM displayed in the bidding interface. Platform fees, commissions from programmatic intermediaries, and additional costs related to custom audiences can sometimes weigh as much as the bid itself. Optimizing an advertising budget in 2024 requires mastering these layers of costs even before touching the targeting parameters.
Digital Markets Act and advertising cost audit: what advertisers can demand
Since March 7, 2024, the Digital Markets Act (DMA) grants advertisers a concrete right: to request daily information, ad by ad, from designated platforms (gatekeepers) about the prices paid, associated fees, and the metrics that determine them, at no cost. This right can also be exercised by an authorized third party.
In practice, this leverage remains underutilized. Most advertisers continue to manage their campaigns solely through native dashboards, without cross-referencing this data with the detailed reports made available by the DMA. We find that the discrepancies between the cost displayed in a campaign manager and the actual billed cost can reach several percentage points, depending on the mediation chain.
To exercise this right, a formal request must be made to each relevant platform. A guide detailing the online advertising rates on Hi Business usefully complements this process by outlining cost ranges by channel.
Priority verification points
- Compare the amount charged by the platform with the displayed budget spent in the campaign manager, on a daily rather than monthly basis.
- Identify service fees or programmatic commissions not detailed in the standard reporting, particularly on display networks.
- Check if automatic bidding generates spikes in cost per click during certain time slots or audience segments.
Budget allocation between search, social ads, and retail media
The European digital advertising market grew by 16% to reach €118.9 billion in 2024, according to IAB Europe’s AdEx Benchmark report. This growth is not evenly distributed among formats. Retail media captures an increasing share of investments, but measuring results in retail media remains a friction point for advertisers looking to compare performance channel by channel.
Deciding between search, social ads, and retail media is not a fixed allocation. The distribution depends on the decision-making cycle of the target customer. An impulsive purchase product justifies an overweighting in social ads and retail media. A long-cycle B2B service directs the budget towards search and remarketing.
Criteria for channel advertising arbitration
Search (Google Ads, Bing Ads) remains the channel where purchase intent is most explicit. The cost per click varies greatly depending on industry competition, but the conversion rate is generally higher than on social networks.
Social ads (Meta, LinkedIn, TikTok) offer fine behavioral targeting. On LinkedIn Ads, the platform’s own recommendation is to test with at least €100 per day or a total of €5,000 over a month to obtain statistically usable data. This testing threshold is often underestimated by advertisers who spread too low budgets across too many simultaneous campaigns.
Retail media is suitable for brands distributed in e-commerce, but requires accepting a still fragmented performance measurement. Conversion data often remains siloed within the distributor’s ecosystem.
Advertising budget optimization: underutilized technical levers
Increasing the budget does not produce proportional results if the campaign structure is flawed. Three technical levers generate measurable performance gains without increasing expenses.
Bid segmentation by device and time slot
Automatic bidding smooths costs throughout the day. However, the cost per conversion can sometimes vary from simple to double between mobile in the evening and desktop during the day. Applying manual bid adjustments by device and time slot allows for concentrating the budget on the most profitable combinations.
Exclusion of non-performing audiences
In social ads campaigns, excluding audiences that click without converting mechanically reduces the cost per acquisition. Exclusion lists (audiences that have already converted, geographic segments outside the catchment area, irrelevant age groups) should be updated weekly.
Management of automatic placements
Platforms default to activating all their placements (news feed, stories, reels, audience network). Some placements consume budget without producing measurable conversions. Disabling low-performing placements after two weeks of data is usually sufficient to improve overall return on investment.
Measuring the true acquisition cost and adjusting advertising campaigns
The CPA (cost per acquisition) displayed in campaign managers reflects only part of the actual cost. It often excludes the time spent on management, agency fees, the production cost of advertising creatives, and unitemized platform commissions.
Calculating a complete CPA requires integrating all direct and indirect costs related to the number of attributed conversions. This approach sometimes radically changes the ranking of channels by profitability. A channel with a low platform CPA may turn out to be more expensive than a channel with a high nominal CPA if the ancillary fees are heavier.
Budget adjustments should rely on sufficient analysis windows. Modifying an allocation after three days of data produces only noise. A window of two to four weeks, aligned with the product or service’s buying cycle, provides actionable signals for redistributing spending between channels and campaigns.
Optimizing an online advertising budget relies less on the amount invested than on the granularity of tracking. Auditing actual fees through the DMA, segmenting bids by usage context, and calculating a complete acquisition cost are three actions that significantly change the profitability of campaigns without requiring additional budget.
