Google has added a new Cost Slider to the Performance Max Channel Reporting Beta. You can now see the Share of Cost for each channel within your Performance Max campaigns. Simply turn it on, and you’ll instantly see what portion of your budget each channel consumes.
Performance Max runs campaigns across several Google Ads channels, but advertisers have had little clarity on how budgets are divided between them.
To address this concern, Google’s new toggle brings greater visibility into channel-level spending, giving marketers more transparency and control over their budget allocation.
What is the Share of Cost Toggle in PMax?
The Share of Cost toggle, also known as the Cost Slider, is a reporting feature in PMax campaigns that, when activated, calculates and displays each channel’s percentage of total campaign spend.
Share of Cost = Spend on a given channel ÷ Total PMax campaign spend.
The metric is displayed in a clear and easy-to-read format.
It gives advertisers quick and intuitive insights. This simple addition dramatically increases clarity and brings much-needed transparency to budget allocation, which until now was hidden within aggregated spend data.
Why This Update Matters: Key Benefits for Advertisers
Here are the top benefits of the Share of Cost metric:
1. Clearer Budget Allocation
The Share of Cost metric reveals exactly how much of your total PMax budget is divided across channels: Search, Shopping, Display, Video, Discover, Gmail, and more.
2. Smarter Spend & Optimisation Insights
By comparing Share of Cost with metrics like conversion share, ROAS (return on ad spend), or CPA (cost per acquisition), marketers can detect:
- Channels that are overspending with low ROI
- Channels that underperform relative to spend, warranting reduction or tweaking
This intersection of cost and performance data forms the bedrock of effective, data-driven campaign refinement.
3. Stronger Scaling Opportunities
If a channel shows a high ROAS or low CPA but only takes a small slice of your spend, that’s a signal to scale up. Advertisers can pivot to shift more budget toward these underutilised and high-performing placements.
The Bigger Picture: Making PMax More Transparent
Since its debut, Performance Max has been seen by many as a “black box”. Many advertisers call it “powerful” but complain that it lacks transparency.
This new toggle is part of a broader wave of enhancements to dispel that notion:
- Enhances trust and control
- Encourages more sophisticated, transparent campaign management
- Aligns PMax functionality with advertiser needs for deeper insights and flexibility
How To Use The Share of Cost Toggle
Getting started with the new Share of Cost toggle is simple, but knowing how to apply the insights is where the real value lies.
- Access Your PMax Dashboard: Go to your Performance Max campaign reporting view inside Google Ads.
- Enable the Cost Slider: Switch on the new Share of Cost toggle. This activates the calculation and breakdown of budget distribution by channel.
- Review the Channel Breakdown: Once enabled, you’ll see each channel’s percentage of the total spend, whether it’s Search, Shopping, Display, YouTube, or Discover.
- Cross-Check With Performance Data: Compare spend share with key performance indicators such as conversions, ROAS, or CPA. This helps determine whether each channel is pulling its weight.
- Make Optimisation Decisions: Analyse, compare, and optimise budget allocation based on insights.
- Reduce spend on channels that consume a large share but deliver weak results.
- Identify underfunded or high-performing placements and consider increasing their share.
- Use this data regularly to refine allocations and improve efficiency.
By following these steps, advertisers can transform what was once a “black box” budget allocation into actionable intelligence for smarter decision-making and long-term scaling.
Tips to Maximise the Value of the Share of Cost Toggle
1. Compare Spend vs. Conversions
Look at each channel’s share of cost alongside its share of conversions. Find channels with disproportionate spend vs. returns. This makes it easy to spot placements that consume too much budget without delivering proportional results.
2. Focus on Scaling High-Performers
If a channel has strong ROAS or a low CPA but only takes up a small portion of your spend, consider increasing its budget allocation. Reallocate budgets to high-ROAS, low-spend channels. These high-performing channels can unlock incremental growth.
3. Monitor Trends Over Time
Don’t just check the toggle once. Use it regularly to spot shifts in channel efficiency. Monitoring changes over weeks or months helps identify shifts in channel efficiency and ensures your budget remains optimised.
4. Use in Combination With Other Reports
For a holistic strategy, layer Share of Cost data with asset reports, audience insights, and search term data. Together, these tools provide a more complete picture of where your money is going and how effectively it’s working.
Potential Limitations and Future Considerations
At this stage, the Share of Cost toggle is only available within the PMax Channel Reporting Beta. Here are some important limitations to keep in mind:
- Beta Availability: The Share of Cost toggle is currently only available as part of the PMax Channel Reporting Beta. The rollout may be gradual and not available to every account right away.
- Cost-Only View: The toggle only displays budget distribution across channels. It does not provide deeper attribution insights, meaning it should always be paired with metrics such as conversions, ROAS, or CPA for full context.
- Learning Curve: Advertisers who are less experienced with multi-channel budgeting may need guidance to interpret the data and act on it effectively.
Why It Still Matters
Despite these constraints, the Share of Cost toggle is a significant advancement. By breaking out spend distribution, Google has shifted PMax reporting from being largely opaque to becoming far more operational.
- It gives advertisers clear visibility into how budgets are allocated.
- It supports data-driven optimisation, making it easier to spot overspending or underfunded high-performers.
- It opens the door to scaling opportunities, helping marketers maximise returns.
Need a fresh perspective? Let’s talk.
At 360 OM, we specialise in helping businesses take their marketing efforts to the next level. Our team stays on top of industry trends, uses data-informed decisions to maximise your ROI, and provides full transparency through comprehensive reports.
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