Remotely measuring the arterial blood oxygen saturation (SpO2) in visible light (Vis) involves different probing depths, which may compromise calibratibility. This paper assesses the feasibility of calibrating camera-based SpO2 (SpO2,cam) using red and green light. Camera-based photoplethysmographic (PPG) signals were measured at 46 healthy adults at center wavelengths of 580 nm (green), 675 nm (red), and 840 nm (near-infrared; NIR). Subjects had their faces recorded during normoxia and hypoxia and under gradual cooling. SpO2,cam estimates in Vis were based on the normalized ratio of camera-based PPG amplitudes in red over green light (RoG). SpO2,cam in Vis was validated against contact SpO2 (reference) and compared with SpO2,cam estimated using red-NIR wavelengths. An RoG-based calibration curve for SpO2 was determined based on data with a SpO2 range of 85–100%. We found an $$A^{*}_{rms}$$ error of 2.9% (higher than the $$A^{*}_{rms}$$ for SpO2,cam in red-NIR). Additional measurements on normoxic subjects under temperature cooling (from $$21\,^{\circ }{\text{C}}$$ to $$