How to Choose Swim Fins

Swimming fins are designed to help swimmers — both competitive and recreational — develop a more powerful kick, increase kick tempo, and improve ankle flexibility and leg strength. They also help swimmers move through the water faster and improve body position, making them one of the most valuable pieces of swimming equipment you can own.

Since swim fins come in a wide array of styles that vary in blade length, stiffness, material, and heel design, this guide from the SwimOutlet swim team helps you choose the pair that best meets your training needs — whether you're in open water or a pool.

Training Fins: Blade Length

The length of the fin blade has the biggest impact on how it affects your workout. The longer the blade, the more water resistance it creates — meaning your legs work harder, but you also kick at a slower rate. Each blade length serves a different training purpose:

Short Blade Fins

Short blade fins (approximately 12–16 inches total length) create resistance in the water while forcing a faster kick, making them ideal for freestylers and backstrokers. Shorter fins help swimmers develop proper kicking tempo and technique that closely mimics their natural, unfinned kick. Most lap swimmers and swimmers on competitive swim teams use these short "Zoomer"-style fins for everyday training.

Best for: Race-tempo training, kick technique, freestyle/backstroke, experienced swimmers, building stroke-specific leg strength.

Long Blade Fins

Long blade fins (approximately 20–24 inches) provide significantly more propulsion per kick, making them best for young swimmers who are still learning how to move in the water, snorkelers, and recreational swimmers. Longer fins also excel at improving ankle flexibility and leg endurance, and they're the preferred choice for focused drill work at any level — the extra propulsion lets you concentrate entirely on upper-body technique without sinking.

Best for: Beginners, drill work, dolphin kick development, ankle flexibility, snorkeling.

Notched (V-Cut) Fins

Notched fins feature a V-shaped cut in the blade edge that mimics the natural path of the foot through the water. Most notched fins use the same short blade design that promotes proper kicking technique, making them popular with serious competitive swimmers. The notch reduces drag at the end of each kick cycle for a more fluid motion.

Monofins & Breaststroke Fins

Monofins and breaststroke fins are specialty training tools with specific purposes. Monofins force swimmers to keep their feet together as they kick, enforcing correct butterfly/dolphin kick movements and building core undulation. Breaststroke fins are curved to allow swimmers to execute a correct breaststroke kick (impossible with traditional straight fins) while increasing resistance — they're the only fin type compatible with the breaststroke kick motion.

Blade Stiffness & Material

The stiffness of the fin blade determines how much resistance each kick generates — and the material determines both stiffness and comfort:

The stiffer the blade, the more resistance it provides. While this sounds appealing for building leg strength, an overly stiff fin also leads to a slower, less effective kick when you take the fins off. Softer blade material provides a more natural movement through the water — and for most swimmers, that translates to better technique transfer from finned to unfinned swimming.

Some fins include channels — grooves molded into the blade that direct the flow of water over the foot. The more the fin is designed to mimic the feel of swimming without fins, the more benefit you'll get from training in them.

Choose by Training Goal

Not sure which fin to pick? Start with what you're trying to improve:

• Kick technique & tempo → Short blade, soft silicone fins. Promotes a quick, natural kick that transfers directly to racing.
• Leg strength & power → Short or medium blade, stiffer rubber fins. More resistance per kick builds muscle.
• Ankle flexibility → Long blade fins. The extended blade gently stretches the ankle joint through a fuller range of motion with each kick — especially beneficial for runners and triathletes with stiff ankles.
• Body position & drill work → Long blade fins. Provides enough propulsion to keep hips high while you isolate technique elements.
• Dolphin kick / butterfly → Long blade fins or monofins. Amplifies the full up-and-down kick motion.
• Breaststroke kick → Breaststroke-specific curved fins only. Standard straight fins cannot be used with the breaststroke kick.
• Confidence & buoyancy (beginners) → Long blade fins. Extra propulsion makes swimming feel easier and builds confidence.

Fin Heel Styles

Most lap swimming fins are "full foot," meaning they encase the entire foot like a shoe. However, some models come with an adjustable back heel strap instead. Here's how to choose between them:

Full Foot (Closed Heel)

A soft rubber or silicone pocket fully encloses the foot, providing a secure, shoe-like fit that stays in place during hard kicking. Because the foot is totally encased, an improper fit can lead to rubbing and blisters — carefully check the size chart and compare with your shoe size before purchasing. Full foot fins are the standard for pool training and competitive swimmers.

Open Heel (Strap)

Open heel fins use an adjustable strap across the back of the ankle. This usually results in less rubbing on the heel and is easier to get on and off, but may not provide the same secure fit as a full foot fin. Open heel fins are more common in diving and snorkeling but are available in some training models. They're a good option if you need to share fins across different foot sizes or if you wear neoprene booties for open water swimming.

Preventing Blisters

Some swimmers get blisters from fins, especially when breaking in a new pair. If this happens, wear fin socks — thin neoprene socks specifically designed to prevent chafing between skin and fin. You can also apply a small amount of body glide or petroleum jelly to problem areas. Silicone fins generally cause fewer blisters than rubber fins due to their softer foot pockets.

How to Size Your Swim Fins

Proper sizing prevents blisters, foot cramps, and wasted energy. Follow these guidelines:

• Snug but not tight — Your fin should fit like a firm handshake. You don't want any sliding or heel slippage, but you also shouldn't have to force your foot in or feel pinching.
• Size up if between sizes — Your feet swell slightly during exercise, so if you're between sizes, go up. You can always add fin socks for a tighter fit.
• Check heel coverage — The foot pocket should fully enclose your foot with minimal exposed skin. Exposed heels are the #1 cause of fin blisters.
• Compare to your shoe size — Most swim fin brands size in standard shoe sizes. Always consult the manufacturer's specific size chart, as sizing can vary between brands.
• Wiggle test — You should be able to slightly wiggle your toes inside the fin. If your toes are jammed against the end of the blade or completely compressed, the fin is too small.

Fins for Kids & Young Swimmers

For children and young swimmers, long blade fins in a soft material are generally the best starting point. The extra propulsion helps kids maintain good body position while they learn stroke mechanics, and the softer material is gentler on developing feet. Key considerations for youth fins:

• Prioritize a secure fit — kids' feet grow fast, so check sizing each season.
• Choose bright colors so fins are easy to spot on a busy pool deck.
• Start with shorter, slower fin sets and gradually increase distance as leg strength develops.
• Floating fins (fins that float when dropped) are easier for kids to find and retrieve in the water.

When NOT to Use Swim Fins

Fins are an excellent training tool, but swimming with them all the time will make it harder when you have to take them off. To get the most benefit without developing dependency:

• Limit fin usage to 20–30% of your total workout yardage. Alternate between finned and unfinned sets.
• Don't use fins to mask technique problems. If you can only swim with good body position while wearing fins, you need to address the underlying technique issue (usually a weak kick or poor head position).
• Remove fins for your main sets. Use fins for warm-up, drill work, and specific kick sets — then take them off for your primary distance or interval sets.
• Fins are not allowed in most swim competitions — so you need to be equally strong without them.

Pair Your Fins with Other Training Gear

Fins work best as part of a complete training equipment rotation:

• Kickboards — Isolate your kick for pure leg training. Use with short fins for tempo work or long fins for endurance.
• Swim paddles — Combine with fins for a full-body resistance workout. See our paddles vs. resistance gloves guide.
• Swim snorkels — Eliminates breathing rotation so you can focus entirely on kick technique and body position while wearing fins.
• Pull buoys — Alternate between pull buoy sets (arms only) and fin sets (legs emphasized) for balanced training.

For a deeper comparison of short vs. long fins, see our Short Fins vs. Long Fins guide.

Swim Fin Advice

The right fins are valuable training tools that help you increase leg strength, develop proper kicking technique, and add speed and variety to your swim workouts. Once you have the right fit and model, you're sure to enjoy the boost fins bring to your training. Check out the most popular swim training fins from top brands like FINIS, Speedo, and TYR!

FAQs

What are the best swim fins for training?

For most competitive swimmers, short blade silicone fins are the best everyday training fin. They promote a natural kick tempo, build race-specific leg strength, and are comfortable for long sets. Popular choices include the FINIS Zoomers Gold, Speedo Switchblade, and TYR Stryker silicone fins. For beginners or drill-focused work, long blade fins provide more propulsion and body position support.

Should I get short fins or long fins?

Short fins are better for race-tempo training and experienced swimmers. Long fins are better for beginners, drill work, and dolphin kick development. Most coaches prefer short fins for everyday training because the kick pattern closely matches natural unfinned swimming. Many swimmers keep both in their bag for different set types.

How do I prevent blisters from swim fins?

Blisters are usually caused by fins that are too tight, too loose, or too stiff. Ensure your fins fit snugly without pinching. Wear thin neoprene fin socks for a protective layer. Silicone fins are generally softer and less blister-prone than rubber fins. Start with shorter fin sets when breaking in a new pair.

What size swim fins should I buy?

Swim fins should fit snugly without squeezing your foot. Most brands size in standard shoe sizes — consult the manufacturer's size chart for the specific model. If you're between sizes, go up rather than down, as your feet swell during exercise. You can add fin socks for a tighter fit.

Do swim fins improve ankle flexibility?

Yes — this is one of the most underrated benefits of training with fins, especially long fins. The resistance of the blade gently stretches the ankle joint through a fuller range of motion with each kick. Over time, this increased ankle flexibility produces a more efficient, propulsive kick even without fins. Swimmers with stiff ankles (common in runners and triathletes) benefit especially from regular fin work.

Can I use swim fins for breaststroke?

Standard straight-blade fins cannot be used with the breaststroke kick — the blade direction is incompatible with the outward-sweeping frog kick motion. Breaststroke-specific curved fins are available that accommodate the breaststroke kick while adding resistance. These are specialty tools typically used by competitive breaststrokers.

How often should I use fins in training?

Most coaches recommend using fins for 20–30% of your total workout yardage. Use them for warm-up, drill work, and specific kick sets, then remove them for your main distance or interval sets. Over-reliance on fins can mask technique issues and create dependence on the extra propulsion.

This guide is written and maintained by the SwimOutlet swim team — competitive swimmers and coaches with decades of combined experience on the pool deck. For more training gear guidance, explore our Short Fins vs. Long Fins guide, paddles guide, and beginner swim workouts.