Logging your workouts is the single most underused tool in fitness. People track their diet, their weight, their sleep, and their steps — but skip the one thing that would make their training dramatically more effective. A weekly workout log turns random exercise into a program.

Pace is the language of running. Whether you are training for your first 5K or chasing a marathon PR, knowing your pace — and what it predicts for other distances — is one of the most useful pieces of data a runner can have. This calculator works three ways: find your pace, predict your finish time, or calculate how far you ran.

The number on the cardio machine is almost certainly wrong. Treadmills, ellipticals, and stationary bikes consistently overestimate calorie burn — sometimes by 30 percent or more — because they do not account for your body weight, fitness level, or actual effort. This workout calorie calculator gives you a more accurate estimate.