calc.gg is a League of Legends build and stat calculator as well as a simple duel simulator. The goal is to help test and gauge champion, item, and build power outside of the LoL practice tool and in a quick and easy manner. It provides an easy way to test relative build strength in a vacuum so you can spend more time practicing in-game. The idea is to let you see approximate stats for ability cooldowns, basic attacks, and active abilities, all accounting for champion and item passives. In addition, it processes the passage of time which allows for visible effects of health/mana regeneration and other time based effects (DoT, slows, etc.), allowing for more accurate results of trades and duels.

Although not all features are implemented, the site is still in progress and is being constantly updated. Stay tuned for more information. If you'd like to see some of the latest updates, head on over to the changelog, where I keep track of nearly all recent changes. Note that this is currently a single developer project, so major updates will take time.