# Agenda: Overview Common inputs in a requests-per-second (RPS) calculation Example of RPS / QPS calculation Techniques to simplify the calculations Handy conversion Table Capacity or Storage Planning Conclusion # Overview: Back-of-the-envelope math is a very useful tool in our system design toolbox. In this article, we will go over how and when to use it, and share some tips on using it effectively. Let’s dive right in. Experienced developers use back-of-the-envelope math to quickly sanity-check a design. In these cases, absolute accuracy is not that important . Usually, it is good enough to get within an order of magnitude or two of the actual numbers we are looking for. For example, if the math says at our scale our web service needs to handle 1M requests per second, and each web server could only handle about 10K requests per second, we learn two things quickly: 1) W e learn that we will need to cluster of web servers, with a l...