Display advertising isn’t flashy. It doesn’t have the impact of a CTV spot or the intent of a Google search click. But it’s the backbone of programmatic advertising for a reason: it works at scale, it’s affordable, and retargeting display campaigns are some of the highest-ROI tactics in digital marketing.
How Programmatic Display Works
The mechanics are straightforward. An advertiser sets up a campaign in a DSP with targeting criteria, budget, and creative assets. When a user loads a web page, the publisher’s ad space goes up for auction via real-time bidding. The DSP evaluates the impression and bids if it matches the campaign’s targeting. Winner’s ad loads on the page.
The whole process takes under 100 milliseconds. Billions of these auctions run every day.
Display Ad Formats
Not all display ads are simple banners. The format affects performance.
Standard display (banners). The classics: 300x250, 728x90, 160x600, and 320x50 (mobile). Static images or simple animations. Cheapest to produce and buy. Still the highest-volume display format.
Rich media. Interactive ads that expand, animate, or include video elements. Higher engagement rates (0.10% to 0.30% CTR vs. 0.05% for standard). More expensive to produce. Require HTML5 development.
Native display. Ads styled to match the surrounding content. They look like articles, recommended content, or editorial features. Higher click-through rates (0.20% to 0.60%) because they blend in. StackAdapt and Taboola/Outbrain specialize in native.
High-impact formats. Full-page takeovers, interstitials, and skin/wallpaper ads. Premium pricing ($15 to $50 CPM). Guaranteed attention but can be intrusive. Best for brand awareness, not direct response.
Display Advertising Costs
Pricing varies by audience, format, and inventory quality.
General audience CPMs:
- Standard display: $2 to $5
- Rich media: $5 to $10
- Native display: $3 to $8
- High-impact: $15 to $50
Legal industry CPMs:
- Standard display: $30 to $50
- Rich media: $40 to $70
- Native display: $35 to $60
- Retargeting: $20 to $40
Legal CPMs are 5x to 10x general market rates. That’s because the audience is smaller (people actively in need of legal services) and the conversion value is high. A single PI case can be worth $10,000 to $100,000+, so paying $50 CPM to reach the right audience is cheap.
Platform fees add 10% to 15% on top of media costs for self-serve DSPs. Managed service fees run 20% to 35%.
Why Display Works: The Retargeting Effect
Display’s real power isn’t in prospecting. It’s in retargeting.
Prospecting display (showing ads to people who’ve never visited your site) has low click-through rates. You’re interrupting someone’s browsing with a banner ad. The average CTR is 0.05%. Most people don’t click.
Retargeting display (showing ads to people who’ve already visited your site) is different. These people know your brand. They’ve already shown interest. Retargeting CTRs run 0.20% to 0.50%, and conversion rates are 2x to 5x higher than prospecting.
The typical retargeting flow:
- User visits your website (from any source: organic search, paid search, CTV ad, direct)
- A pixel fires and adds them to your retargeting audience
- As they browse other sites, your display ads follow them
- They see your brand 3 to 7 more times over the next 14 to 30 days
- When they’re ready to act, they remember your name
For legal advertisers, retargeting is essential. Someone researching “car accident lawyer” might visit 5 to 10 firm websites before calling one. Retargeting keeps your firm top of mind during that consideration phase.
Display Campaign Strategy
Prospecting Campaigns
Goal: Reach new audiences who match your target profile but haven’t visited your site.
Targeting approach: Use third-party audience data (in-market for legal services), contextual targeting (legal and accident-related content), and geo-targeting (your service area).
Budget allocation: 30% to 40% of display budget. This feeds your retargeting pool.
KPI: Cost per site visit, view-through conversions, audience growth.
Retargeting Campaigns
Goal: Stay visible to past website visitors until they convert.
Targeting approach: Pixel-based retargeting of site visitors. Segment by page visited (someone who viewed your “car accident” page is more valuable than someone who bounced from the homepage).
Budget allocation: 40% to 50% of display budget. This is where conversions happen.
KPI: Cost per conversion, assisted conversions, return on ad spend.
Contextual Campaigns
Goal: Show ads on pages relevant to your service without relying on user data.
Targeting approach: Keywords and categories that match your content. A PI firm targets pages about car accidents, workplace injuries, and medical malpractice.
Budget allocation: 15% to 25% of display budget. A privacy-safe complement to audience targeting.
KPI: Brand lift, site visit quality (bounce rate, time on site).
Display and the Full Funnel
Display doesn’t work in isolation. It’s most effective as part of a multi-channel strategy.
Top of funnel: CTV + Display prospecting. Streaming TV ads build awareness. Display prospecting extends reach at lower cost. Together, they create a large pool of people who recognize your brand.
Middle of funnel: Display retargeting. Everyone who visited your site from any channel gets retargeted with display. This is the bridge between awareness and conversion.
Bottom of funnel: Search + Call tracking. When retargeted prospects are ready, they search your name or your practice area. Google Ads captures the click. Call tracking ties the phone call back to the full journey.
Without display retargeting in the middle, the CTV-to-search path breaks. People see your streaming ad, forget your name, and search “car accident lawyer” instead. Your competitor’s PPC ad gets the click. Retargeting prevents that.
Measuring Display Performance
Click-through rate is not the right metric for display. Here’s what to measure instead.
View-through conversions. Someone saw your display ad, didn’t click, but later visited your site and converted. This is how most display-driven conversions happen. Set a 7 to 14-day view-through window.
Assisted conversions. In multi-touch attribution, display often appears in the middle of conversion paths. It assists the conversion without being the last touch.
Incremental lift. Run a holdout test: show display ads to one group and not to another, then compare conversion rates. This is the gold standard for measuring display’s true impact.
Frequency and reach. How many unique users saw your ad, and how many times each? Display performs best at 5 to 10 impressions per user over 14 to 30 days. Too few and they forget you. Too many and you’re wasting budget.
Site visit quality. Look at bounce rate, pages per session, and time on site for display-driven visits. High-quality visits indicate your targeting and creative are aligned.
Common Display Mistakes
Running display without retargeting. Prospecting-only display campaigns produce terrible ROI. Always pair prospecting with retargeting.
Ignoring creative quality. A blurry logo on a white background won’t get attention. Invest in clean, professional creatives with clear calls to action. Test multiple versions.
No frequency caps. Without caps, your ad can show to the same person 50+ times. That’s annoying and wasteful. Set caps at 3 to 5 per day, 15 to 20 per week.
Buying only cheap inventory. $1 CPM inventory exists. It’s also mostly bots, below-the-fold placements, and made-for-advertising sites. Pay more for quality.
Measuring only clicks. Display CTR is 0.05%. Judging display by clicks alone will always make it look like a failure. Use view-through conversions and marketing attribution to see the real picture.