Cost Per Result (CPR) is the definitive metric for measuring campaign efficiency. It is calculated by dividing the total amount spent on a campaign by the number of results achieved. This metric directly quantifies how cost-effectively an advertiser is achieving the specific outcomes defined by their campaign objective (e.g., cost per purchase, cost per lead). A lower Cost Per Result indicates higher efficiency, as it means less money is being spent to acquire each desired outcome.

A. Cost: This term is ambiguous. While related, "Cost Per Result" is the specific, standardized metric used to measure the efficiency of achieving an objective.

B. Spend: This represents the total amount of money paid for a campaign. It indicates the scale of investment but provides no information on the effectiveness or efficiency of that investment.

D. Results: This metric shows the total number of desired actions taken. While important for measuring volume, it does not account for the cost incurred to achieve those actions, and therefore cannot indicate efficiency.

1. Meta Business Help Center, "About cost per result."

Reference: In the main body of the article, it states, "Cost per result shows you how cost-efficiently you achieved the objectives you set in your ad campaign. It's calculated by taking the total amount spent and dividing it by the number of results." This directly confirms that CPR is the metric for efficiency against objectives.

2. Meta Blueprint, "100-101: Meta Certified Digital Marketing Associate Study Guide."

Reference: Section 4.1, "Determine campaign results," discusses key metrics for evaluating performance. It emphasizes the relationship between spend and results, which is encapsulated in the Cost Per Result metric as the primary indicator of cost-effectiveness.

3. Meta Business Help Center, "Glossary of advertising terms."

Reference: The glossary defines "Cost per result" as "The average cost per result from your ads." It defines "Result" as "The number of times your ad achieved an outcome, based on the objective and settings that you selected." The combination of these definitions establishes CPR as the measure of cost against objective-based outcomes.