An organic light emitting device includes: a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode, the organic layer including an emission layer, wherein the organic layer includes a first compound, a second compound, a third compound, and a fourth compound, and the first compound to the fourth compound satisfy Equations 1 to 8: E1,LUMO≥E2,LUMO+0.15 electron volts (eV)  Equation 1 E1,HOMO≥E2,HOMO+0.15 eV  Equation 2 E1,T1≥E4,T1  Equation 3 E2,T1≥E4,T1  Equation 4 E3,T1≥E4,T1  Equation 5 E3,LUMO≥E2,LUMO+0.1 eV  Equation 6 −5.6 eV≥E3,HOMO  Equation 7 Egap1≥Egap3.  Equation 8