Dark Souls 3: guide to upgrade the Estus flask to the maximum
In Dark Souls 3 there are 11 Fragments Estus to find to maximize the health flask.
By finding all the fragments and delivering them to the blacksmith in the Firelink Shrine, as well as unlocking the "Estus Definitivo" trophy / achievement, it is possible increase the number of health flasks you can carry. It starts with 3 Estus flasks + 1 ash bottle. Combined with the 11 Estus fragments this will bring you a total of 15 flasks.
As these represent your health potions it is highly recommended that you find these shards as soon as possible.
Remember that if you have missed any, you can always go back and retrieve them at any time, even after beating the final boss.
In the video you can see above the position of all the fragments to reinforce the Estus Flask is shown, in the order in which the various areas of the game in which they are located become accessible.
You can always check in your inventory how many you already have. At the blacksmith it is possible to transform the ash flasks into Estus flasks and vice versa.
Don't forget to also consult the Dark Souls 3 cheats and guides tab for many other useful guides on this game.