If you run a website or app that serves ads, you’ve likely faced the challenge of unsold ad inventory. These leftover impressions, known as remnant ad impressions, are those that remain after your direct deals or premium programmatic campaigns have run their course. While they may not command top dollar, they still hold value. Setting up backfill is the key to monetizing them effectively.
This guide walks you through how to set up backfill in a straightforward, actionable way so you can turn every impression into revenue.
What Is Backfill and Why Does It Matter?
Backfill refers to the process of filling unsold ad inventory with ads from secondary sources. These sources typically pay less than direct deals but offer consistent demand and reliable fill rates.
Remnant ad impressions are those that remain unsold after your primary monetization efforts. Instead of letting these impressions go to waste, backfill allows you to monetize them using several back-fill ad networks.
Step-by-Step Guide to Setting Up Backfill
1. Audit Your Ad Inventory
Begin by identifying which parts of your inventory consistently go unsold. Use your ad server, such as Google Ad Manager, to analyze:
- Fill rates
- CPMs (Cost Per Mille)
- Geographic and device breakdowns
- Time slots with low demand
This helps you pinpoint where backfill is most needed.
2. Choose the Right Backfill Partner
Your choice of backfill partner depends on your goals, such as simplicity, higher CPMs, or global reach. Common options include:
| Backfill Partner | Strengths |
| Google AdSense | Easy setup, reliable fill, global reach |
| Pub Venture | Scalable, Reliable, Global, User-friendly |
| adops.network | Transparent, Flexible, Optimized, Supportive |
| streamlyn | Targeted, Innovative, Efficient, Responsive |
Each partner has its own strengths. AdSense is ideal for beginners, while the above-mentioned tag-based ad partners offer more advanced features and potentially higher earnings.
Once you’ve selected your backfill partner, follow these steps to get them live:
- Finalize the partnership and sign a contract outlining terms and pricing
- Receive the ad tag and ads.txt entries from your partner
- Upload the ads.txt file to your website’s root directory to ensure proper authorization
- Implement the ad tag on your site as instructed
- Set up a house or price priority line item in Google Ad Manager targeting the desired inventory
- Use deal-based pricing to align with your partner’s terms
- Test the implementation to confirm ads are serving correctly
- Monitor performance to track fill rate, CPM, and overall revenue impact
This ensures your remnant inventory is monetized efficiently while maintaining control and transparency.
3. Integrate with Google Ad Manager
Most publishers use Google Ad Manager (GAM) to manage their ad inventory. Here’s how to set up backfill in GAM:
- Create ad units to define the ad slots on your site
- Set line items for direct deals and programmatic campaigns
- Add backfill as a fallback line item with lower priority
- Use dynamic allocation to allow GAM to choose the highest-paying ad source automatically
5. Optimize Ad Formats and Placement
Remnant inventory performs better when:
- Ads are placed above the fold
- Formats are mobile-friendly
- Sizes match standard IAB units such as 300×250 or 728×90
Use A/B testing to find the best-performing combinations. Better placement and formatting can improve viewability and CPMs.
6. Monitor Performance and Adjust
Use analytics tools to track:
- Fill rate
- CPM trends
- Viewability
- Revenue per thousand impressions (RPM)
Adjust your partners and ad placements based on performance data. Regular monitoring helps you maximize revenue and identify underperforming areas.
Common Mistakes to Avoid
- Ignoring viewability. Low viewability leads to poor CPMs and advertiser dissatisfaction.
- Overloading pages with ads. This can hurt user experience and SEO.
- Not testing partners. Always test multiple SSPs to find the best mix.
- Skipping reporting. Without data, you cannot optimize.
Avoiding these mistakes ensures that your backfill strategy remains effective and sustainable.
Real-World Example
Suppose you run a news website with 1 million monthly impressions. Your direct deals cover 60 percent, and programmatic fills another 25 percent. That leaves 150,000 impressions unsold.
By setting up backfill with AdSense and other backfill partners, you could earn:
- AdSense: $0.50 CPM × 100,000 impressions = $50
- Backfill Ad Partners: $0.70 CPM × 50,000 impressions = $35
That’s $85 per month from inventory that would otherwise earn nothing. Over a year, that adds up to over $1,000 in additional revenue.
Final Thoughts
Setting up backfill is not just a technical fix. It is a strategic move to maximize your ad revenue. Whether you are a small blog or a large media outlet, every impression counts. By choosing the right partners, configuring your ad server smartly, and continuously optimizing, you can turn remnant inventory into a reliable income stream.
If you need help choosing the best backfill partner for your niche or setting up header bidding, feel free to ask. I can guide you through the process step by step.
