Butterfly Stroke: Technique, Kick Timing, and Drills Explained

The butterfly stroke is a face-down competitive swimming stroke in which both arms pull underwater and recover together over the surface, while the legs fire two dolphin kicks per arm cycle and the torso undulates in a whip-like motion to drive the swimmer forward. It ranks among the four strokes swum in types of swimming strokes, and it’s widely regarded as the hardest one to learn — not because any single piece is complicated, but because every piece has to fire in the same tight window, stroke after stroke, with almost no natural rest.

Why Butterfly Is So Demanding

Freestyle and backstroke are alternating strokes — one arm works while the other recovers, which spreads the load out and gives each side a brief break. Butterfly removes that break entirely. Both arms pull, both arms recover, and both legs kick together, twice per cycle, which means the shoulders, lats, core, and hip flexors all have to fire in unison on every single stroke.

That’s also why butterfly is the second-fastest competitive stroke, behind only freestyle. The simultaneous double-arm pull generates a strong, short burst of propulsion, and the undulating body motion — chest pressing down as the hips rise, then hips driving down as the chest and head lift — keeps the swimmer’s center of mass moving forward instead of stalling between strokes. Get the timing wrong, though, and that same lack of a rest phase turns into a stroke that eats energy fast and produces very little speed.

The Technique, Step by Step

Butterfly is best learned as three separate motions — body undulation, the dolphin kick, and the arm cycle — that get layered together once each one is solid on its own.

1. Set the body position. Swim face-down with the head in a neutral, mostly-down position. The undulation starts at the chest, not the head: press the chest down and let the motion travel through the hips and into the legs, like a wave passing through the body.
2. Add the dolphin kick. Keep the legs together and mostly straight, with a slight bend at the knee on the downbeat. Both feet kick simultaneously in a whip-like snap, driven from the hips rather than the knees. See our full breakdown of the dolphin kick for drills that isolate this motion in deep water before combining it with the arms.
3. Time the two kicks per cycle. The first, smaller kick happens as the arms enter the water and stretch forward. The second, more powerful kick comes as the arms sweep back and begin recovery — this kick lifts the hips and shoulders and provides the momentum that carries the arms up and over the water.
4. Pull with both arms together. Hands enter shoulder-width apart, thumbs first, then sweep outward, down, and in toward the midline in a keyhole or hourglass shape before pushing back past the hips. Unlike breaststroke swimming, where the arm pull stays underwater throughout, butterfly’s pull finishes with the arms exiting the water for recovery.
5. Recover both arms over the water simultaneously. This is butterfly’s signature move and a strict rule requirement — the arms must swing forward together, low and wide over the surface, elbows leading slightly, and re-enter in front of the shoulders.
6. Breathe on a forward lift. As the arms finish their pull and begin recovery, lift the chin just enough to clear the water, inhale quickly, then snap the head back down before the arms re-enter. Breathing every stroke is fine for beginners; competitive swimmers often breathe every second stroke to cut drag.
7. Finish and touch with both hands. World Aquatics rules require both hands to touch the wall together and simultaneously at every turn and finish — touching with one hand is a disqualification.

Common Butterfly Mistakes

Mistake	Why It Hurts the Stroke	Fix
Lifting the head too high or too early	Sinks the hips and stalls the undulation	Lead the breath with the shoulders; lift only enough to clear the mouth
Kicking from the knees	Produces a weak, splashy kick with little propulsion	Drive the kick from the hips with straight-ish legs
Recovering arms underwater or asynchronously	Illegal in competition and kills rhythm in practice	Practice single-arm butterfly to isolate the over-water recovery
Skipping the second kick	Flattens the undulation and stalls momentum before the next pull	Count kicks out loud during drills: kick-pull, kick-recover
Rushing the stroke rate	Burns energy fast with no speed payoff	Slow down and lengthen each pull before adding tempo

Drills That Build Butterfly

• Vertical dolphin kick: Kick in deep water with arms crossed or overhead, isolating the undulation and kick rhythm without the arms.
• Single-arm butterfly: One arm stays extended at your side while the other completes a full pull-recovery cycle, making the over-water recovery easier to learn one side at a time.
• Fly kick on your back: Dolphin kicking face-up highlights the same hip-driven whip motion used in the standard kick.
• 3-kick drill: Take three dolphin kicks per arm cycle instead of two, slowing everything down so the undulation timing becomes obvious.

Butterfly rewards patience more than raw strength. Swimmers who rush straight into full-stroke reps without drilling the kick and undulation separately tend to plateau early, while those who build the rhythm piece by piece — the same progression covered in our tips to start swimming guide — usually pick up a clean, efficient stroke faster.

Butterfly in Competition

Butterfly has been a standalone Olympic event since 1956, after its arm and kick elements — developed separately in the early 20th century — were combined into one stroke in the 1930s. It’s swum over 50m, 100m, and 200m at the elite level, and it’s also the opening leg of the individual medley in most competitive formats. Because of its physical cost, butterfly races are typically shorter than freestyle or backstroke events at the same level, and even elite swimmers rarely hold a fast, clean butterfly stroke much past 200 meters without significant fade.