A bid is the maximum amount you are willing to pay when someone interacts with your ad, usually a click. In Google Ads you can set bids yourself, keyword by keyword, or let a bidding strategy set them automatically for every auction.
How a bid works
Every time someone searches, Google runs an ad auction among the advertisers whose keywords match. Your bid is one input. Google combines it with the expected quality of your ad and landing page, the search context, the assets you have available and minimum thresholds to calculate Ad Rank. Ad Rank decides whether your ad shows and in what position.
A higher bid does not guarantee the top spot, and you rarely pay your full bid. On search, the price of a click is broadly the least you needed to keep your position, so a strong, relevant ad can win a higher position for less than a weaker competitor pays.
The unit of a bid depends on the campaign. Search and Shopping usually bid per click. Some display and video campaigns bid per thousand impressions or per view. With manual CPC, you set a maximum per click on each keyword or ad group. With Smart Bidding strategies such as Target CPA or Maximise Conversions, Google sets a fresh bid in each auction using signals like device, location, time and audience, aiming at the goal you give it.
Why it matters
Bids control how much of the available demand you can capture and at what price. Bid too low and you appear rarely, or only in lower positions where fewer people click. Bid too high and you pay for clicks whose expected value does not justify the cost.
The right bid follows from your numbers, not from what competitors seem to pay. If a new customer for your Bristol accountancy practice is worth around £600 in first-year fees, one in twenty clicks becomes a client, and you want ads to cost no more than a quarter of that value, you can afford roughly £7.50 a click. That arithmetic matters whether you set bids by hand or give Smart Bidding a target. Without it, any bid is a guess dressed up as a decision.
Common mistakes
- Raising bids to reach the top position as a matter of pride, regardless of profit.
- Setting one bid for every keyword when some are worth far more than others.
- Using Smart Bidding before conversion tracking is accurate, so the system optimises for the wrong thing.
- Changing bids or targets every few days, so automated strategies never settle.
- Ignoring ad and landing page quality, which can lower costs more than any bid change.
How to act on it
Start with what a conversion is worth and what share of that you can spend on advertising. That gives you a sensible ceiling for cost per click or a target cost per acquisition. If you have little conversion data, manual CPC or Maximise Clicks with a cap can be a reasonable way to gather it. Once you have steady conversions, Smart Bidding usually outperforms hand-set bids.
Then review bids by results, not by position. Look at cost per conversion by keyword, and adjust where the gap between cost and value is widest. If you want a bidding approach built from your own margins and tested properly, I set this up as part of PPC management.