Windows 10 is expected to see a decline in its user base due to rising costs of Extended Security Updates (ESUs), which total approximately per device for three years. Historically, user loss accelerates after the third year of support ends, as seen with Windows 7. In contrast, Windows 11 is experiencing significant growth, commanding 71.5% of all Windows installations as of September 2026, following a stagnant year. This increase is linked to the end of support for Windows 10 in October 2025, prompting migrations to Windows 11.