It is very accurate and easy to use. You can find out how much space you have left on your phone by entering your phone number and the size of your message, it does not require any additional software. The app has no option for offline usage. For example, if I need to calculate my SMS length in a train station or bus stop, where there are no WIFI connection, I would like to be able to keep using the app without having to download it first. I highly recommend this app because it's easy to use and works great. You can easily calculate how long will you send your SMS messages when sending them from your mobile phone.