1. Save the ingredient at least once (the button appears only on existing items).
2. Make sure Display Name, Base Weight and Base Unit are correct; the AI estimates nutrition for that exact amount.
3. Click Calculate Macros with AI. A confirmation shows the name and "Base Weight: X unit"; click Calculate.
4. Sprwt asks the AI for every macro configured in your account, fills the QNT inputs (rounded to each macro's decimals), turns off Auto Macros on sub-recipes, shows "Macros calculated successfully with AI" and then auto-saves the form.

The call needs Sprwt AI credits (at least $0.07 available); if your balance is too low a no credits pop-up opens instead. If the AI cannot estimate the item you get its error message and nothing is changed.