This app allows you to calculate easily the number of lands you have to include in your MTG decks.
How to do it?
1. Select your deck size (Constructed, Limited or Commander). These decks have a default number of lands, but you can edit that in settings.
2. Count the mana symbols of your cards. Add them in the app, with the buttons or using the slider.
4. Profit! Check the number of lands to include.
It's perfect to calculate the number of lands to include during drafts and pre-releases.