Collatz studied at universities in Germany including the University of Berlin under Alfred Klose, receiving his doctorate in 1935 for a dissertation entitled Das Differenzenverfahren mit höherer Approximation für lineare Differentialgleichungen (The finite difference method with higher approximation for linear differential equations).
Collatz studerede på Humboldt-Universität zu Berlin under Alfred Klose, hvor han erhvervede sit doktorat i 1935 for en afhandling kaldet Das Differenzenverfahren mit höherer Approximation für lineare Differentialgleichungen (Den endelige differensmetode med højere approximation for lineære differentialligninger.)