Valve hasn't released a few official Steam figures in several years, but reasonable math from a reputable source reckons the biggest store in PC gaming is hovering around 200 million monthly active users, which would make it more than 50% larger than the entire PlayStation platform.
This soft figure comes from Simon Carless' GameDiscoverCo newsletter. Carless used some pretty basic math and alternate data sources to estimate Steam's growth over the past few years, and we can check it ourselves with some equally simple arithmetic based on Valve's 2025 Steam report.