Radius evolution curves for a massive (5 M_Jup) temperate gas giant. Left: radius evolution of a 5 M_Jup assuming different C/O ratios. A low C/O ratio can slightly increase the planet radius by 2% at young ages (<100 Myr). Right: radius evolution of the same planet at a constant C/O ratio and different initial entropy values. A hot start can increase the planet radius significantly for ages of <100 Myr. We adopt an equilibrium temperature of 100 K across all models. Markers are labeled with their corresponding internal temperature, T_int.