Dumbbell Flys Flat
Dumbbell flat flys are an isolation chest exercise targeting the pectoral muscles. The wide arcing motion stretches and contracts the chest through a large range of motion, making it effective for developing chest width and muscle definition.
How to do it
- Lie flat on a bench holding a dumbbell in each hand, arms extended directly above your chest.
- With a slight bend in your elbows, lower the dumbbells out to the sides in a wide arc.
- Continue lowering until you feel a deep stretch across your chest.
- Reverse the motion and bring the dumbbells back up in the same arcing path until they meet above your chest.
- Repeat for the desired number of repetitions.
Form cues
- Keep a slight, fixed bend in your elbows throughout the movement.
- Lower the dumbbells in a wide arcing motion until you feel a gentle chest stretch.
- Plant your feet firmly on the floor and keep your lower back in a natural position.
- Squeeze your chest muscles to return the weights to the starting position.
Breathing: Inhale as you lower the dumbbells out to the sides in a wide arc, and exhale as you bring them back up together.
Common mistakes
- Straightening the arms completely puts too much unwanted stress on the elbow joint.
- Using weights that are too heavy often turns the fly into an accidental press and reduces chest focus.
- Lowering the dumbbells too far can strain the shoulder joints, so stop when you feel a normal stretch.
Muscles worked
Primary: chest. Secondary: shoulders, triceps.
Suggested sets & reps
Get fitter
3 sets × 10–12 reps, rest 60–90 seconds
Lose weight
3 sets × 12–15 reps, rest 60 seconds
Build muscle
3–4 sets × 8–12 reps, rest 90 seconds
Easier, harder & alternatives
Make it easier
Make it harder
Alternatives
Take care if…
- If you feel shoulder discomfort or sharp pain in the chest joint, reduce the range of motion or stop the exercise.
General educational guidance, not medical advice. Stop on sharp pain and check with a qualified professional if unsure.
Get this in your plan
Create a free account for an AI-built plan that puts moves like this into your week.
Start free →Frequently asked questions
Should my arms be completely straight during a dumbbell fly?
No, you should keep a slight, soft bend in your elbows at all times to protect your arm joints from strain.
How heavy should the dumbbells be for flat flys?
Start much lighter than what you use for a bench press. This exercise isolates the chest, so lighter weights allow for better control and form.
What if I feel this exercise more in my shoulders than my chest?
That usually means the weights are too heavy or you are lowering your arms past your torso line. Lower the weight and focus on a hugging motion.