How Long Should a Workout Be? The Science-Backed Answer45 minutes? 90 minutes? Research reveals the optimal workout duration for strength, cardio, and weight loss — and why longer isn't always better.Frequently asked questionsIs TimerRush free?Completely free — no account required.Where can I try the timers mentioned in this guide?All timers are at timerrush.com. Bookmark /t/25m or /t/5m for quick one-click access.