Nutrient bottles come with charts that assume you remember last week and own a chemistry set. This does the sum for you. Pick your brand — eleven of them — your feed line, the stage you are at and your tank size, and it gives you millilitres per bottle plus the pH and EC to aim for. No more mixing by eye or feeding a seedling like it is week six of flower. It is built around the manufacturers' own schedules, so you are following the people who made the bottle, just without the squinting and the mental arithmetic.
Eleven brands, the ones most growers actually run, each with its own lines and schedules built in. Pick the brand and line you have on the shelf and the amounts come out matched to it — you are not translating one brand's chart onto another's bottles, which is how most feeding quietly goes wrong.
Tell it the brand, the line, your stage and 10 litres, and it returns the millilitres for each bottle in that line — not a guess, the maker's rate scaled to your tank. Change the tank size and the numbers scale with it, so a bigger or smaller reservoir is the same job.
It shows the maker's own target pH and EC for your brand and stage, right next to the amounts — CANNA Terra in early soil, say, sits around pH 5.8 to 6.2 with EC 0.7 to 1.3. Those targets shift by brand and medium, so go by the figure the tool gives for the line you are running, and check it against your own pen before you pour.
No — start around half and work up. The schedules are a ceiling, not a dare, and more plants are hurt by overfeeding than by under. Feed at the lower end, watch the leaf tips for burn, and climb toward the full rate only if she is hungry and healthy. You can always add; you cannot easily take back.