Hydration Vest Sizing Guide: Measure Once, Buy Once

Hydration vest sizing follows one number: your chest circumference. Measure it, match it to the brand's own chart, then test the vest loaded. A vest should feel snug and move with your torso while still letting you take a full breath.

How to measure your chest

1. Wrap a soft tape measure around the fullest part of your chest, level across your back.
2. Breathe normally and read the relaxed number.
3. Compare it with that brand's chart for that model. Do not use your shirt size.

Example: the LECAMO ROOT5 chart is S 78 to 90 cm, M 90 to 102 cm, L 102 to 115 cm, XL 115 to 125 cm. Other brands publish chest ranges for their vests too. Each brand's chart applies only to its own patterns.

Between two sizes

Check the brand's guidance first. If there is none, think about what you wear underneath and how the straps adjust: a vest with more strap range can tighten further, while a vest at the end of its adjustment cannot. When the seller allows returns, try both sizes loaded at home. LECAMO accepts return requests within 14 days of receiving an order, with size exchanges subject to stock.

Four fit checks

• With full flasks, jump in place. The vest should move with you, not separately.
• Take a deep breath. You should feel the vest without fighting it.
• Reach test: remove, drink from and re-seat each flask while walking.
• Check that the shoulder straps sit flat. If they leave marks during a short walk at home, adjust before running.

Sizing mistakes that cause returns

• Buying by shirt size. Shirt and vest sizes measure different things.
• Sizing only for winter layers. Size for your usual running kit and use the straps when you add a layer.
• Ignoring torso length. If a vest bunches at the waist or rubs your neck, the pattern may be wrong for you even in the right chest size.
• Testing it empty. Fill the flasks and pack your normal load before judging fit.

Still moving after you sized it right?

Bounce can also come from packing, half-empty flasks or strap adjustment. More checks: vest bounce and fit guide.

FAQ

Should a hydration vest be tight?

Snug, not tight. It should move as one with your torso, and you should still be able to breathe deeply.

Do vests loosen over time?

Recheck the fit from time to time and adjust the straps if it feels looser.

Why does my vest ride up?

Common causes are a size that is too large, a torso-length mismatch or a load packed low. Fix the size and packing before overtightening straps.