APR ↔ EAR Converter

Convert a nominal APR with a given compounding frequency to an Effective Annual Rate (EAR), or convert an EAR back to a nominal APR.

Used only for the nominal APR side (APR assumes this compounding cadence).
Formulae

APR → EAR: EAR = (1 + APR/m)m − 1, where m is compounding periods per year.

EAR → APR: APR = m × ((1 + EAR)1/m − 1).

Monthly rate = (1 + EAR)1/12 − 1. Daily rate ≈ (1 + EAR)1/365 − 1.