As the App Store and Google Play&rsquo;s revenue topped $58 billion last year, it is true to say the global app market is absolutely booming. However, the percentage of apps which are considered successful by their developers and publishers still staggers around 0.01%. In case you want to launch an app business this year or think of building a mobile application to expand your brand presence, here&rsquo;s the list of mobile app metrics you should track to succeed with your project.5 Key Metrics for Mobile AppsInstalls. Most apps are distributed for free. 50% of app users don&rsquo;t make any in-app purchases (IAPs) whatsoever. The median price of a paid iOS app went as low as $ 1.02 last year. How come tracking downloads, installs and uninstalls is still relevant? With these metrics, you&rsquo;ll learn how users find your app and where they download it from &ndash; and will be able to change your marketing strategy accordingly. In case you&rsquo;re promoting your app on social media and ad networks like AdMob and Cheetah Mobile, you should still make use of independent tracking tools (App Annie, Sensor Tower, Apple Analytics, etc.) to compare downloads stats provided by your ad networks with the actual downloads data. Having said that, app store search and getting featured by Google Play/App Store editors remain the most effective application discovery channels &ndash; and that&rsquo;s why app store optimization (ASO) and UX/UI issues should be addressed early in the dev process;App usage. Here the vague term refers to the total number of app users and the number of active users. With over 5 million apps available on Google Play and the App Store, the number of apps that are used only once during the first six months of ownership ranges between 26% and 24%. In other words, the fact that someone took the time to download your application does not prove you&rsquo;re doing a good job of it. Some folks might think you&rsquo;re abusing the microtransactions model or send too many push notifications. Other smartphone owners might not find your app useful or fail to figure out how to use it. A healthy ratio between the total number of app users and the number of active users is 30-40%. As a businessman, you should map a mobile app user&rsquo;s journey, identify potential breach points and continuously improve your product to stay within the lines;Engagement and retention. There are some more mobile app usage metrics to consider, including engagement, retention and churn rates, as well as the average length of an app session. Although US users now spends 2 hours 51 minutes on their smartphones daily (92% of this time is actually spent in apps), the length of the average app session is just 5 minutes (it&rsquo;s 10 minutes for top 100 apps which include social media apps, messengers and dating applications). Once again, the figure does not prove anything by itself; the fact that someone uses your app hardly means they&rsquo;re enjoying it. Tracking ratings and reviews on Google Play and the App Store is a great way to get feedback on performance and UX issues; you can also use in-app messages for the same purpose. &ldquo;Why bother?&rdquo; you may ask. The thing is, keeping a mobile app user is 5 to 25 times cheaper than acquiring a new one. As a rule, mobile apps lose 80% of their audience within 3 months &ndash; and it usually takes us anything between 3 and 7 days to decide whether we will continue using the application or not. This basically means you have 72 hours to re-engage users and deliver value to them. Appreneurs who turn to in-app messages and push notifications manage to improve retention rates by up to 46%. Also, you can enhance your app with customer loyalty program elements to boost the average revenue per user (ARPU);Customer lifestyle value. In 2018, running a mobile app business is still about finding the perfect balance between Customer Acquisition Cost (CAC) and Customer Lifetime Value (CLV). According to eMarketer, the CAC metric (which is the total cost of your sales and marketing efforts divided by the number of new users) is now estimated at $ 85.23 (iOS) and $ 67.57 (Android). Of course, we&rsquo;re talking about getting a first-time user who makes an IAP here; the average cost per install (CPI) is only $ 4.12. Since the majority of smartphone owners do not download new apps for months (and will probably abandon your app within 90 days), measuring CPI is no longer important, though. What you need to know is how many people are willing to spend money on IAPs and subscribe to your services - and how much revenue they&rsquo;ll bring over their lifespan (ARPU x 1/churn rate). That&rsquo;s how you measure CLV. If it takes you $ 50 to get a paying user who spends $ 10 per month, you&rsquo;d better keep the guy interested for at least 6 months to get your money back;&nbsp;Virality. Here comes the best (and trickiest!) part. Thanks to virality, app developers and publishers can eliminate the CAC stage and convert a stream of people into a stream of money without spending a cent. What makes a viral app and how could you possibly measure the K-factor? Although only 5% of app users make IAPs or download paid applications, there are other users who would like to access premium features for free and therefore don&rsquo;t mind promoting your app on social media and sending the App Store/Google Play download links to their friends. The K-factor is the number of invites sent by a user (i) multiplied by the percent of invites that actually convert (c). You can also measure virality by dividing the organic app downloads over a certain period by the number of active users over the same period. With the data, you&rsquo;ll be able to tell how many new users each of your existing customers can bring and how soon it&rsquo;s going to happen. To enable the invitation feature, you should contact a mobile app dev company with the relevant portfolio (make sure to check ours at r-stylelab.com while you&rsquo;re at it) and think of incentives like bonus points and access to premium app features/content that is likely to fuel viral growth.Data is key to understanding your mobile app performance and making timely changes to your marketing strategy. Provided you conduct a proper market research (which includes target audience and competitor analysis) and address a reliable software development service company, measuring the mobile app analytics metrics I&rsquo;ve listed above will help you stay on the same page with your customers and offer a clear solution to the problem they&rsquo;re faced with.