Full Definition
Smart Bidding is a subset of Google Ads automated bidding strategies that use machine learning to optimise for conversions or conversion value. Unlike manual bidding — where you set a fixed maximum CPC — Smart Bidding analyses dozens of signals in real time and adjusts your bid for every single auction. The main Smart Bidding strategies are: **Target CPA (Cost Per Acquisition)**: Tell Google what you're willing to pay for each conversion. It adjusts bids to maximise conversions at that target cost. **Target ROAS (Return on Ad Spend)**: Tell Google the revenue return you want per rupee spent. It adjusts bids to maximise conversion value at that target ratio. **Maximise Conversions**: Get as many conversions as possible within your budget, without a specific CPA target. **Maximise Conversion Value**: Get as much total revenue as possible within your budget. **Enhanced CPC (ECPC)**: A hybrid — you set manual bids, but Google adjusts them up or down based on likelihood of conversion. Smart Bidding works best when your campaign has solid historical data — most strategies require at least 30–50 conversions per month to function reliably. Below that threshold, the algorithm doesn't have enough data to learn from, and performance can be erratic. Actionable tip: When launching a new campaign, start with Maximise Clicks (a manual-ish strategy) to build data. Once you have 30+ conversions, switch to Target CPA or Target ROAS and set a conservative initial target based on your historical data.