Speedo Short/Medium Blade Fin Size Guide

This size guide covers the Speedo Short Blade Fin and Speedo Medium Blade Fin, available in sizes XXS–XXL covering UK shoe sizes 13 Junior to 13. Both fins are made from soft, natural rubber and feature an open-toe pocket for a comfortable fit across a wider range of foot sizes. Sizing is identical across both models — select the fin that suits your training goals, then use this guide to find your size.

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Short Blade Fin
Speed & Technique

Designed for strong fitness swimmers, the Short Blade Fin helps promote a fast-beat kick. Its shorter blade length demands more leg speed and power output per stroke, making it ideal for speed work and sprint sets.

  • Promotes a fast-beat kick technique
  • Ideal for speed work, drills and technique sessions
  • Soft, natural rubber engineered for comfort
  • Open-toe pocket for a flexible fit
  • Best for: experienced swimmers and sprint training
Medium Blade Fin
Strength & All-Purpose

The all-purpose Medium Blade Fin is ideal for fitness swimmers looking to build leg strength and speed. The medium blade length provides more propulsion per kick, making it suitable for a wider range of training sessions.

  • Builds leg strength and swimming speed
  • Ideal for speed work, drills and technique sessions
  • Soft, natural rubber engineered for comfort
  • Open-toe pocket for a flexible fit
  • Best for: fitness swimmers and all-round training
Sizing Table — Speedo Short & Medium Blade Fin
Size UK Shoe Size EU Shoe Size
XXS 13 Jnr – 1 Jnr 32 – 33.5
XS 2 – 3 34.5 – 35.5
S 4 – 5 37 – 38
M 6 – 7 39 – 40.5
L 8 – 9 42 – 43
XL 10 – 11 44.5 – 45.5
XXL 12 – 13 47 – 48

Sizing is identical for both the Short Blade Fin and Medium Blade Fin. The open-toe pocket design accommodates a range of foot widths within each size band.

Fit Notes — Speedo Short & Medium Blade Fin
  • Use your standard shoe size to select the correct fin size. If your shoe size falls within a size range, that size is correct for you.
  • The open-toe pocket means the fin does not need to enclose your toes — your toes will extend beyond the end of the pocket. This is normal and by design.
  • The fin should fit snugly around the heel and foot with no significant movement or slipping during use. Excessive movement will cause blisters and reduce efficiency.
  • Both fins are made from soft, natural rubber which will ease and mould slightly with use. New fins may feel firmer than expected — this is normal.
  • Wet the fins and your feet before putting them on to make them easier to fit and reduce friction during use.
  • Do not wear fins outside the pool — the rubber sole is not designed for walking on hard surfaces and will wear prematurely.
  • Rinse in fresh water after every use and store away from direct sunlight to preserve the natural rubber.
  • Unsure? Contact our team or call +44 1827 330600. Speak to a member of staff at Allens if you are unsure.
Frequently Asked Questions — Speedo Short & Medium Blade Fin

The key difference is blade length, which determines how the fin feels in the water. The Short Blade Fin has a shorter blade that requires more leg speed per kick — it is designed for strong, experienced swimmers and is ideal for sprint speed work and fast-beat kick technique. The Medium Blade Fin has a longer blade that provides more propulsion per kick, making it better suited to fitness swimmers looking to build leg strength and all-round swimming speed. Both are made from the same soft natural rubber with an open-toe pocket design.

The Medium Blade Fin is generally better suited to beginners and fitness swimmers. Its longer blade provides more propulsion with each kick, which makes it easier to maintain speed and feel the benefit of the fin without needing a very fast kick rate. The Short Blade Fin is designed for stronger swimmers who already have good kick technique and want to develop their speed further. Speak to a member of staff at Allens if you are unsure which is right for you.

Yes. Sizing is identical across both the Short Blade Fin and the Medium Blade Fin. Use the sizing table above to find your size based on your UK or EU shoe size, and the same size applies to both models. The open-toe pocket design also means the fit is flexible across a range of foot widths within each size band.

The open-toe pocket means the foot pocket of the fin does not enclose your toes — your toes extend beyond the end of the pocket and into the blade of the fin. This is normal and by design. It allows the fin to fit a wider range of foot widths and shapes within each size, and also allows a more natural foot position during kicking. The heel and midfoot should fit snugly with no significant movement.

If your shoe size falls between two fin sizes, speak to a member of staff at Allens who will be happy to advise on the best option for your foot size and intended use.

Yes. The XXS size covers UK junior shoe sizes 13–1, making these fins suitable for younger swimmers. The open-toe pocket design and soft natural rubber make them comfortable for younger swimmers. If your child is just starting out with fins, the Medium Blade Fin is recommended as it is easier to use than the Short Blade Fin. Always supervise children when using fins in the pool.

The Speedo Short and Medium Blade Fins are designed primarily for pool use during training. While the natural rubber construction would withstand occasional use in open water, they are training fins intended for use during speed work, drills and technique sessions rather than open water swimming. For open water or triathlon use, a longer fin or purpose-built open water fin would be more appropriate.

Rinse your fins thoroughly in fresh water after every use to remove chlorine and salt, which can degrade natural rubber over time. Store them flat or hanging, away from direct sunlight and heat sources. Do not leave them in direct sunlight for extended periods as UV exposure will cause the rubber to deteriorate. Do not walk on hard surfaces in the fins — the soles are not designed for walking and will wear prematurely.