About this tool
The Pokémon IV Calculator works backwards from a stat you can see in-game to the Individual Values (IVs) that could have produced it. Because the stat formula floors at each step, several IVs often map to the same displayed stat, so this tool returns the full range of possibilities rather than pretending there is always one answer. Pick a stat, enter the displayed value, the base stat, the level, the EVs and the nature, and it lists every IV from 0 to 31 that reproduces that exact number. It runs entirely in your browser.
Internally it inverts the Generation III+ formula. For HP it checks floor(0.01 × (2 × Base + IV + floor(EV / 4)) × Level) + Level + 10, and for other stats floor((floor(0.01 × (2 × Base + IV + floor(EV / 4)) × Level) + 5) × Nature), iterating IV across 0–31 and keeping only the values whose result equals your displayed stat. The nature modifier (×1.1 raised, ×0.9 lowered, ×1.0 neutral) is taken from the same 25-nature table used by the stat calculator, so choosing the right nature narrows the window correctly.
The result shows the minimum and maximum IV that fit, whether the value is pinned to a single IV, and how many IVs match. Higher levels and larger displayed stats generally pin the IV more tightly, which is why breeders check IVs at level 100 or after adding EVs — each extra bit of scaling shrinks the range. If no IV in 0–31 can produce the number you entered, the inputs are inconsistent and the tool says so instead of guessing.