What is the best swimming style to make my chest stronger?

Breast stroke and butterfly

Butterfly. Definitely. It should even help your arms too.

I am a freestyler and if you do full on sprints you will blast out your chest muscles big time. Proper execution of the stroke matters a lot. Supplement your swimming with lots of pushups.

I was a butterfly-er… I competed in the 100 and 200 fly events in college as well as the 200 and 400 IM. It’s still my favorite stroke 22 years later.

The butterfly, done correctly, will give you the best quads, hams, back, abs, chest and shoulders you could ask for.

Butterfly is the best stroke to build upper body strength. Unfortunately, it is also the hardest stroke to swim. I would recommend alternating between the Freestyle and Butterfly strokes in practice.