Zakāt and the four schools
The four Sunni schools share the same framework, 2.5% on accumulated zakatable wealth held above the niṣāb for one lunar year. They differ mainly on a few details. Below is the range of positions; the app lets you pick a school (or Custom) to set these.
Niṣāb thresholds
All four schools: about 87.48g of gold or 612.36g of silver. Most charities use the lower silver threshold so more people benefit.
Worn gold/silver jewelry
Ḥanafī: zakatable, worn or stored. Mālikī, Shāfiʿī, Ḥanbalī: exempt if worn for genuine personal use; zakatable if stored or excessive.
Combining gold + silver toward niṣāb
If neither metal alone reaches niṣāb: Ḥanafī and Mālikī combine their values; Shāfiʿī does not combine (each must reach its own niṣāb); Ḥanbalī is reported both ways.
A minor's wealth
Ḥanafī: generally not due on a minor's wealth (zakāt tied to adulthood). Mālikī, Shāfiʿī, Ḥanbalī: due, paid by the guardian.
If wealth dips below niṣāb mid-year
Ḥanafī: if you hold niṣāb at the start and end of the year, zakāt is due even if it dipped between. Mālikī, Shāfiʿī, Ḥanbalī: niṣāb should be maintained throughout the year.
Recipients
All four: the eight categories of Sūrat al-Tawbah (9:60); across all schools, zakāt generally may not be given to the family of the Prophet ﷺ (Banū Hāshim).
Where the schools differ, at a glance
They agree on the 2.5% rate and the niṣāb (87.48g gold or 612.36g silver). The table below summarises the main points of difference.
Zakat Made Easy, Mufti Faraz Adam: the position this app follows, used with the author's permission.
These references corroborate the position; they are not an endorsement of this app.