We consider a Sturm-Liouville operator with an integrable potential 𝑞 on the unit interval 𝐼 = [0, 1]. We consider a Schrödinger operator with a real compactly supported potential on the half line and on the line, where this potential coincides with 𝑞 on the unit interval and vanishes outside 𝐼. We determine the relationships between eigenvalues of such operators and obtain estimates of eigenvalues in terms of potentials.