A CPA calculator can help you save money on your marketing campaigns by calculating your cost per acquisition (CPA). This metric measures how much it costs you to acquire a new customer through your marketing efforts. By understanding your CPA, you can make adjustments to your campaigns to ensure that you are not spending more than necessary to acquire new customers. Additionally, a CPA calculator can help you track your progress over time, allowing you to see how your campaigns are performing and identify areas where you can improve your efficiency.