How long should a gym workout be?

A session’s length is mostly sets × (time per set + rest). A set takes under a minute; rest between sets of bigger lifts is usually 2 to 3 minutes (how long to rest). Add 5 to 10 minutes to warm up.

Muscle growth tracks the number of hard sets each muscle gets per week: around 10 or more weekly sets per muscle beat fewer in a meta-analysis, and a later review put the useful range for trained lifters at about 12 to 20. Those sets can be spread over three short sessions or two long ones.

A review of time-efficient training found that people short on time can still make good progress with as few as about 4 hard weekly sets per muscle, mostly on multi-joint exercises.

• Pick 3 or 4 multi-joint exercises (a squat or leg press, a press, a row or pulldown, a hinge) that cover most muscles.
• Pair exercises for different muscles as supersets, resting after each pair.
• Take each set close to failure, with one or two reps left, so fewer sets still count.
• Train three or four short days a week instead of two long ones.

Tell Spot the time you have, say 30 or 45 minutes, and the equipment you can use, and it builds a workout that fits and puts it in your GymStreak plan. Session length is also one of the things your weekly plan is built around when you set up the app.