PRR or project rate of return is about how much money your business must earn on its marketing in order to be profitable. Profit is different then revenue, it takes in to account other factors than just marketing that take away from the revenue of a sale. PRR is usually around 25% however, every business is a little different. Newer businesses might have a higher PRR because they are being more aggressive when starting out, more well established businesses might have a lower PRR.
You will need to use your PRR in order to calculate other KPI's or key performance indicators so it is important to learn it. It will also give you a guide to keep your marketing efforts in check, so you don't spend to much. Calculating your PRR requires you to know the profits on the different products and services that you offer.
You will need to take into account everything that it costs you to run your business and how much each product or service costs you. After that you should have a idea of the profit you make for each product or service. Most businesses already know what amount of profit they want to make and set there prices accordingly. So with that in mind your PRR is just a percentage of that number and allows you to remain in profitable. For example say you are selling paper notebooks and it for each one you sell at $10 it costs you $4 that leaves you with a $6 profit. In most cases the PRR is 25% meaning for every dollar you spend in marketing you earn $4. So in this scenario a PRR of 25% would mean that you could spend $1.50 on marketing to sell a $10 notebook.
PRR is not the most exciting KPI in my opinion but it is good to know and again you will use it calculate other KPI's. If you are running a small business don't get to hung up on the PRR you will more than likely need to change it regularly in order to meet the demands of running a small business. So make sure you use it, even if it lacks the excitment of other KPI's.