Choosing the right bidding strategy is one of the most impactful decisions you'll make for your Google Shopping campaigns. According to Wordstream's Google Ads benchmarks, CPCs vary dramatically by industry — making bid strategy selection even more critical. Manual bidding gives you precise control but demands constant attention. Automated bidding leverages Google's AI but requires trust and sufficient data. So which approach is right for your business?
This guide breaks down both strategies, explains when each makes sense, and helps you decide whether to go manual, automated, or a hybrid approach. We'll cover the specific bid strategies available, the data requirements for each, and common pitfalls to avoid.
Understanding Your Bidding Options
Google Shopping offers several bidding strategies ranging from fully manual to fully automated. Here's what's available:
Manual CPC (Cost-Per-Click)
With Manual CPC, you set the maximum amount you're willing to pay for each click on your Shopping ads. You control bids at the product group level.
- How it works: You set a max CPC for each product group. Google enters auctions up to that bid.
- Control level: Maximum - you decide every bid
- Data requirement: None - works from day one
- Best for: New campaigns, low-volume products, accounts needing precise margin control
Enhanced CPC (ECPC)
Enhanced CPC is a hybrid approach. You set manual bids, but Google can adjust them up or down based on conversion likelihood.
- How it works: Your manual bid serves as a baseline. Google increases bids for searches more likely to convert and decreases for those less likely.
- Control level: Medium - you set base bids, Google adjusts
- Data requirement: Low - works with some conversion data
- Best for: Advertisers wanting automation benefits while maintaining bid control
Maximize Conversions
Maximize Conversions is a fully automated strategy that optimizes for the highest number of conversions within your budget.
- How it works: Google sets bids automatically to get as many conversions as possible within your daily budget
- Control level: Low - you set budget only
- Data requirement: Medium - needs some conversion history
- Best for: Campaigns focused on volume over efficiency, sufficient budget flexibility
Target ROAS (Return on Ad Spend)
Target ROAS optimizes bids to achieve a specific return on ad spend. This is the most common automated strategy for e-commerce.
- How it works: You set a target ROAS (e.g., 400%). Google adjusts bids to achieve that return on average.
- Control level: Low-Medium - you set the target, Google handles execution
- Data requirement: High - needs 15-30+ conversions per month minimum
- Best for: Established campaigns with consistent conversion data and clear profitability targets
Key Insight
Target ROAS is the gold standard for e-commerce automation, but it requires sufficient data. Google recommends at least 15 conversions in the last 30 days, though 50+ provides significantly better performance. As Shopping ads expand to new placements like AI Mode, automated bidding becomes even more important for optimizing across surfaces you can't manually control.
Head-to-Head Comparison
Let's compare these strategies across the dimensions that matter most for Shopping advertisers.
Control & Flexibility
| Capability | Manual/ECPC | Automated |
|---|---|---|
| Product-level bid control | Full control | No control |
| Margin-specific bidding | Yes, per product group | Only via campaign segmentation |
| Bid adjustments (device, location) | Full control | Ignored (algorithm decides) |
| React to market changes | Manual updates required | Automatic adjustment |
| Seasonal optimization | Requires manual planning | Learns patterns automatically |
Data Requirements
| Strategy | Min. Conversions/Month | Optimal Performance |
|---|---|---|
| Manual CPC | 0 - works immediately | Any volume |
| Enhanced CPC | 5-10 | 20+ |
| Maximize Conversions | 15 | 30+ |
| Target ROAS | 15-30 | 50+ |
Important
These are conversions at the campaign level, not the account level. A campaign with only 5 conversions per month will struggle with Target ROAS even if your account has hundreds of conversions in other campaigns.
Time Investment
| Strategy | Setup Time | Ongoing Management |
|---|---|---|
| Manual CPC | High (set every bid) | High (constant optimization) |
| Enhanced CPC | High (set base bids) | Medium (periodic reviews) |
| Maximize Conversions | Low (set budget) | Low (monitor results) |
| Target ROAS | Low (set target) | Low (adjust target as needed) |
When to Use Each Strategy
Use Manual Bidding When:
- You're launching a new campaign: No conversion data means automated strategies have nothing to optimize against. Start manual, gather data, then consider switching.
- You have low conversion volume: Products that convert rarely (high-ticket items, niche products) may never generate enough data for automation.
- You need margin-specific control: If products have vastly different margins, manual bidding lets you bid higher for high-margin items and lower for low-margin ones. Custom labels can help segment products by margin tier.
- You're testing new products: Manual control lets you deliberately push or pull back on new product visibility without waiting for the algorithm to learn.
- You don't trust the algorithm: Some advertisers prefer the transparency of knowing exactly what bid they're paying.
Use Automated Bidding When:
- You have sufficient conversion data: 30+ conversions per month at the campaign level gives automated strategies enough signal to optimize effectively.
- You want to save time: Manual bid management across thousands of products is unsustainable for most teams.
- You have clear ROAS goals: Target ROAS works best when you know exactly what return you need to be profitable.
- Your margins are relatively consistent: If most products have similar margins, a single ROAS target can work across the catalog.
- You trust the data: Accurate conversion tracking is essential. If your tracking is broken, automation will optimize toward broken signals.
Use a Hybrid Approach When:
- You have mixed conversion volumes: Use automation for high-volume products, manual for low-volume ones.
- Margins vary significantly: Segment campaigns by margin tier, apply different ROAS targets or use manual for specific segments.
- You're transitioning: Start new products on manual, migrate to automated once they have sufficient data.
Reality Check
Most successful Shopping advertisers end up with some form of hybrid approach. Pure manual becomes unmanageable at scale. Pure automation can miss margin nuances. The right mix depends on your catalog, volume, and team capacity.
How to Set Up Each Strategy
Setting Up Manual Bidding
- Structure your product groups: Create granular product groups based on brand, category, price tier, or margin. More granularity = more bid control.
- Set initial bids based on value: Calculate your break-even CPC: (Product Price × Margin × Conversion Rate). Bid below this for profitability.
- Apply bid adjustments: Adjust bids by device (mobile often converts lower), location (high-value regions), and time of day.
- Review and optimize weekly: Check search terms, adjust bids based on performance, add negative keywords.
Setting Up Target ROAS
- Ensure accurate tracking: Verify conversion tracking is working correctly. Enable enhanced conversions if possible.
- Calculate your target: Determine your break-even ROAS and set your target above it. Be realistic - aggressive targets limit volume.
- Start conservatively: If your current ROAS is 300%, start with a 250% target to give the algorithm room to learn, then tighten.
- Allow learning time: Don't judge for at least 2-3 weeks. The algorithm needs time to gather signals and optimize, and conversion lag means early data is incomplete.
- Adjust gradually: Change targets by 10-20% at a time. Large jumps destabilize the algorithm.
Common Mistakes to Avoid
1. Switching to Automation Too Early
Automated strategies need data to learn. Switching a campaign with 5 conversions per month to Target ROAS sets it up for failure. The algorithm will make wild bid swings trying to find patterns in insufficient data.
2. Setting Unrealistic ROAS Targets
If you set a 500% Target ROAS but your historical performance is 250%, the algorithm will aggressively cut bids, leading to volume collapse. Start at or slightly below your current performance and optimize up gradually.
3. Not Segmenting by Margin
A single Target ROAS across products with 10% margins and 50% margins guarantees sub-optimal performance. Segment campaigns by margin tier and set appropriate targets for each.
4. Ignoring Conversion Tracking Issues
Automated bidding optimizes toward whatever you're tracking. If your tracking is broken, miscounted, or missing conversions, the algorithm will optimize toward broken data. Audit your tracking before enabling automation.
5. Making Too Many Changes
Every change resets the learning period. If you're adjusting ROAS targets daily or restructuring campaigns weekly, the algorithm never stabilizes. Make changes infrequently and deliberately.
6. Abandoning Manual Insights
Even with automated bidding, you should still review search term reports, monitor product performance, and identify wasted spend. As Search Engine Land emphasizes, automation handles bidding, not strategy.
Measuring Bidding Strategy Success
How do you know if your bidding strategy is working? Track these metrics:
- ROAS trend: Is your return improving, stable, or declining over time?
- Conversion volume: High ROAS but tiny volume isn't success - you may be bidding too conservatively.
- Impression share: Losing impression share to budget? You might need higher budgets. Losing to rank? Your bids may be too low.
- CPA stability: Wild CPA swings suggest the algorithm is struggling or lacks data.
- Wasted spend percentage: Products consuming budget without converting. Automation doesn't eliminate this - you still need to monitor.
Tools like SKU Analyzer can help you track product-level performance across campaigns, making it easier to identify which products need manual attention versus which are performing well with automation.
Frequently Asked Questions
Should I use manual or automated bidding for Google Shopping?
It depends on your situation. Use manual bidding when you have limited conversion data, need precise control over individual product bids, or have specific margin requirements per SKU. Use automated bidding when you have sufficient conversion volume (50+ per month), want to save time on bid management, and trust Google's algorithm to optimize toward your goals.
What is Target ROAS bidding in Google Shopping?
Target ROAS (Return on Ad Spend) is an automated bidding strategy that optimizes bids to achieve a specific return on ad spend. For example, setting a 400% Target ROAS means Google will try to generate $4 in revenue for every $1 spent. The algorithm adjusts bids in real-time based on signals like device, location, time, and audience.
How much conversion data do I need for automated bidding?
Google recommends at least 15-30 conversions in the last 30 days for Target ROAS to work effectively, though 50+ conversions provides better results. For Maximize Conversions, the threshold is lower but performance improves with more data. Without sufficient data, manual or Enhanced CPC is typically more reliable.
Can I mix manual and automated bidding in Shopping campaigns?
Yes, a hybrid approach is common and often effective. Many advertisers use manual bidding for new products or low-volume SKUs while using automated bidding for products with established performance data. You can also segment campaigns by product category or margin tier and apply different strategies to each.
What's the difference between Enhanced CPC and Target ROAS?
Enhanced CPC (ECPC) adjusts your manual bids up or down based on conversion likelihood, but keeps you in control of base bids. Target ROAS fully automates bidding to hit a specific return target. ECPC is a middle ground between manual and fully automated, while Target ROAS gives complete control to Google's algorithm.
Conclusion
The manual vs. automated bidding debate isn't about which is universally better - it's about which fits your specific situation:
- Choose manual bidding for new campaigns, low-volume products, and when margin control is critical
- Choose automated bidding when you have sufficient data, clear ROAS goals, and want to reduce management time
- Choose a hybrid approach when you have a diverse catalog with varying volumes and margins
Most advertisers evolve their approach over time. Start manual to learn your products and gather data, transition to automation as volume grows, and maintain manual oversight for strategic decisions. The goal isn't to pick one strategy forever - it's to match your bidding approach to your current situation.
Whatever strategy you choose, the fundamentals remain the same: accurate conversion tracking, well-structured campaigns, quality product data, and ongoing performance monitoring. Bidding strategy is just one piece of the optimization puzzle.