Speedo Plus Size Womens Size Guide

This size guide covers Speedo Plus Size adult women's swimwear in sizes 18/40 to 28/50 (equivalent to UK dress sizes 18–28). All measurements are body measurements taken from your own body, not garment measurements. Always use your bust measurement as the primary guide. International size equivalents for Germany (D), France (F), Italy (I), Latin America (Lat Am), and Australia (Aus) are shown in the sizing table below.

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Body Measurement Points
Speedo Plus Size women's swimwear body measurement points — bust, waist and hip
How to Measure

Take all measurements directly against your skin using a soft tape measure. All measurements are body measurements, not garment measurements.

  • A
    BustMeasure around the fullest part of your chest, keeping the tape horizontal and snug but not tight.
  • B
    WaistMeasure at the narrowest part of your natural waist.
  • C
    HipMeasure around the fullest part of your hips and seat, keeping the tape horizontal.

*Waist is measured at the natural waist at narrowest point.

Sizing Table — Speedo Plus Size Adult Female Swimwear
Sizing 18/40 20/42 22/44 24/46 26/48 28/50
International Size Equivalents
UK Dress Size 18 20 22 24 26 28
D (Germany) 44 46 48 50 52 54
F (France) 46 48 50 52 54 56
I (Italy) 50 52 54 56 58 60
Lat Am Talla 40 Talla 42 Talla 44 Talla 46 Talla 48 Talla 50
Aus 16 18 20 22 24 26
Body Measurements (cm)
Bust 111.5 111.5 120 124.5 129 134
Waist* 93 100 107 114.5 121 127.5
Hip 114 120.5 127 133.5 139.5 145.5

*Waist is natural waist at narrowest point. All measurements are body measurements, not garment measurements.

Fit Notes — Speedo Plus Size Women's Swimwear
  • Always use your bust measurement as the primary guide when selecting a Speedo Plus Size swimsuit.
  • Speedo swimsuits are designed to fit closely and securely — they will feel firmer than a regular fitted top. This is intentional and ensures the suit stays in place during swimming.
  • If your bust and hip measurements suggest different sizes, choose the size that fits your bust and check that the hip measurement falls within the size range.
  • Speedo swimsuits are made from chlorine-resistant fabrics that feel firm when new and ease slightly with wear — do not size up based on initial tightness.
  • The swimsuit should feel secure across the bust and back with no gaping, pulling, or riding up.
  • Rinse in cold fresh water immediately after every use. Do not tumble dry, iron, or dry-clean.
  • 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 Plus Size Women's Swimwear

Measure your bust, waist, and hip using a soft tape measure directly against your skin. Use your bust measurement as the primary guide and compare to the sizing table above. If your measurements fall across two sizes, choose the size that fits your bust. International size equivalents are shown in the table as a secondary reference — always prioritise body measurements.

Speedo Plus Size swimwear is specifically designed for UK dress sizes 18–28 (Speedo sizes 18/40 to 28/50), offering a fuller cut across the bust, waist, and hip. Standard Speedo numeric sizing (24–46) covers UK dress sizes 6–22. If you are between the two ranges, the size 18/40 and 20/42 options overlap with the upper end of the standard range — always use body measurements to decide.

If your measurements fall between two sizes, use your bust measurement to decide. Speedo swimsuits are designed to fit closely and will ease slightly with wear. Do not size up based on how the suit feels when you first try it on. Speak to a member of staff at Allens if you are unsure.

Yes — Speedo's chlorine-resistant fabrics feel firm when new and ease slightly with regular use. The suit will mould to your body shape over the first few wears. Do not size up based on how the suit feels when you first try it on — if it fits correctly across the bust and back with no gaping, it is the right size.

Speedo swimsuits are primarily designed for pool use. While the chlorine-resistant fabrics will withstand occasional use in open water or the sea, prolonged exposure to salt water can accelerate fabric degradation. Rinse the suit thoroughly in fresh water after every use. For dedicated open water or triathlon use, a wetsuit or open water-specific suit is recommended.

Rinse your Speedo swimsuit in cold fresh water immediately after every use to remove chlorine, salt, and sunscreen. Hand wash gently with a mild detergent if needed. Do not machine wash, tumble dry, iron, or dry-clean. Store flat and dry, away from direct sunlight. Avoid sitting on rough surfaces in your swimsuit as this can cause premature fabric wear.

Speedo swimsuit sizes do not directly correspond to standard clothing sizes. Always use body measurements to select the correct Speedo size. The international size equivalents in the table are shown as a secondary reference — always prioritise body measurements over clothing size equivalents.