# Optimal cost column

Based on the bid strategy settings, how much you should have spent for conversions on the keywords.

Add this column to a report
1. Do either of the following:

2. Above the performance summary graph, click the Columns button.

3. In the Search for columns box, type the column name.

4. Click + next to the column name in the Available columns list.

For example:

• For CPA strategies, optimal cost is the target CPA × number of conversions (for example, a CPA target of \$10 × 100 conversions = \$1,000 optimal cost).
• For ERS strategies, optimal cost is the target ERS × amount of revenue (for example, an ERS target of 15% × \$10,000 revenue = \$1,500 optimal cost).
• For ROAS strategies, optimal cost is the amount of revenue/target ROAS (for example, \$5000 revenue/200% target ROAS = \$2,500 optimal cost.
• For Floodlight strategies, the CPA, ERS, and ROAS targets are evaluated on an activity-by-activity basis. For example, you're managing a set of keywords related to car rentals, and you set up Floodlight tag bidding for car rentals, hotel rooms, airfare, and cruise packages. Search Ads 360 calculates the optimal cost as follows:
• 20 car rental conversions × \$9 CPA goal = \$180 optimal cost
• 5 hotel room conversions × \$20 CPA goal = \$100 optimal cost
• 5 airfare conversions × \$30 CPA goal = \$150 optimal cost
• 1 cruise conversion × \$700 CPA goal = \$700 optimal cost
• The total optimal cost is \$1130

#### Discrepancies on the bid strategy overview page

Optimal cost is calculated daily based on that day's metrics. For example, if you change your target today, Search Ads 360 doesn't update the optimal cost from last week. Optimal cost always reflects the status of your settings on a given day.

The amount in the Optimal cost column may not reflect the amount in the Revenue column if the bid strategy is using an alternate attribution model. For the keywords in the bid strategy, the Optimal cost column reports spend based on the bid strategy's attribution model. The Revenue column reports revenue for the keywords in the bid strategy based on the last-click attribution model, regardless of the bid strategy's attribution model.

For example, suppose a bid strategy is using the first interaction attribution model which gives the credit for conversions to the first click on an ad. On the 1st of the month, a customer clicks on an ad, but doesn't convert. The customer returns to the ad and converts, but not until the 15th of the month. The Optimal cost column will include the cost of the conversion. The Revenue column won't include the revenue from the conversion because the revenue isn't attributed to the last click on the ad.

Search Ads 360 displays an Optimal cost of 0 for bid strategies with Position goals because there is no associated CPA, ERS, or ROAS.