Microsoft Ads Automated Bidding: tCPA vs tROAS (2026 Benchmarks)

On Google, you can switch to tCPA with 15 conversions. On Microsoft, if you do that, the campaign dies. Microsoft's algorithm is "thirstier" for data. It is also slower to react to changes.

In this "Mega-Authority" guide, we cover:

1. The Thresholds: When to switch?
2. Enhanced CPC: The default king.
3. Max Conversions: The budget drainer.
4. Portfolio Strategies: Sharing data.

Part 1: The Thresholds (50 conversions)

Do not use Target CPA (tCPA) or Target ROAS (tROAS) until you have 50 conversions in the last 30 days at the campaign level.

• If you have 10 conversions, stick to Enhanced CPC.
• Reason: With low data, Microsoft's bid floor logic panics and stops bidding continuously.

Part 2: Portfolio Strategies

If you have 5 small campaigns (10 conversions each). Combine them into a Portfolio Bid Strategy.

• Shared Library -> Bid Strategies.
• Create "tCPA $50".
• Apply to all 5 campaigns.
• Result: The algorithm sees 50 total conversions and can optimize effectively.

Part 3: Max Conversions (Warning)

"Maximize Conversions" without a cap is dangerous. Microsoft will spend $50 for a click if it thinks it might convert. Always set a Maximum CPC limit even on automated strategies (if available). Or, use tCPA instead which inherently limits cost.

Part 4: Learning Phase

Microsoft's Learning Phase is l...o...n...g.

• Google: 7 Days.
• Microsoft: 14-21 Days.
• Rule: Do not touch the campaign for 3 weeks after switching bidding strategies. If you change a budget, it resets.

Part 5: Summary & Checklist

Your Action Plan:

1. Audit conversion volume per campaign.
2. Switch low-volume campaigns to eCPC (Manual).
3. Switch high-volume campaigns (>50) to tCPA.
4. Create Portfolio Strategies for grouped campaigns.
5. Patience: Wait 3 weeks before judging performance.

Feed the machine... slowly.