Oxygen flowmeters are essential for managing oxygen supply in clinical settings. However, no standardized guidelines exist for their accuracy testing, leading to variations in measurement devices and protocols across facilities. While float-type flowmeters and digital flow analyzers are commonly used, their measurement validity remains unclear. This study aimed to evaluate the validity of the digital flow analyzer PF-300 (IMT) compared to the float-type flowmeter RK1350 (KOFLOC) using statistical methods. Forty oxygen flowmeters (N-102, SHIN-EI) were tested at flow rates ranging from 1 to 10 L/min. Lin’s concordance correlation coefficient (CCC), Bland-Altman analysis, and the coefficient of variation (CV) were used to assess measurement agreement and variability. Lin’s CCC was 0.9514 (95% CI: 0.9447–0.9573), indicating substantial agreement. Bland-Altman analysis showed a systematic overestimation by the PF-300 (mean bias: -0.9286 L/min, LoA: -1.8885 to 0.0314 L/min). At low flow rates (1 L/min), greater variability was observed (CV: PF-300 = 9.5%, RK1350 = 8.2%). RK1350 demonstrated higher accuracy for flowmeter calibration. While the PF-300 showed consistent bias, proper correction could enable its use in clinical settings. Further validation across different environments is required.