A standard baseball cap can flatten curls, crush volume at the crown, and leave a visible dent or crease once you take it off — especially if you tuck all your hair up underneath the crown. It doesn't ruin curly hair permanently, but it does temporarily reshape it, and the effect is worse the longer you wear the cap and the tighter the fit. The good news is you have a few real ways around it, from how you wear a normal cap to caps designed specifically to let a ponytail, bun, or braid pass through the back.
Why does a regular baseball cap flatten curly hair?
A normal cap is a closed dome shaped to sit tight against the head, so any hair pushed up inside it gets compressed against the curve of the crown for as long as you wear it. Curls hold their shape less firmly than straight hair, so that pressure shows up as flattening, creasing along the brim line, and static or frizz once released.
The tighter the cap and the longer it's worn, the more pronounced the effect, particularly with looser curl patterns or hair that's been recently washed or styled. Wearing a ponytail, bun, or braid low and letting it hang out the back opening of the cap (where there is one) avoids most of this, since the hair isn't being crushed against fabric — it's just resting outside it.
What is a ponytail-hole cap, and how is it different?
It's a cap built with an opening at the back specifically so a ponytail, bun, or braid can pass through instead of being pushed up and squashed under the crown. Brands like Ponyloop® make caps this way as their main design idea, not as an add-on feature.
Ponyloop's Original and Vintage caps have a back opening the hair passes through, so a ponytail or bun sits outside the cap rather than being crammed inside it. The Glitter version uses a different approach called CrissCross — crossed elastic bands you tuck the hair between, which is meant to hold the hair more securely during movement, like running or sport. Either way, the point is the same: your hair isn't fighting the shape of the cap for space.
Will a ponytail cap work with loose curls, not just a tied-back ponytail?
It works best when the curls are gathered — a ponytail, low bun, twist, or braid — rather than worn fully loose and down. A ponytail-opening cap is built around hair exiting through one spot at the back, so it assumes the bulk of your hair is contained in some way.
If you usually wear your curls fully loose, you'll still get some flattening at the crown and sides no matter what cap you use, since a cap has to sit against the head somewhere. Gathering curls loosely at the nape before pulling them through the opening tends to preserve more shape and volume than trying to stuff loose curls under a standard crown.
How do I keep a ponytail cap fitting well with thick or voluminous curly hair?
Look for a cap sized to fit a wide range of head sizes, and check whether it includes a way to adjust the fit smaller if needed. Thick curly hair adds bulk at the hairline and crown even when the ponytail itself is outside the cap, so fit range matters more than it does for straight hair.
Ponyloop's caps are one-size, made to fit roughly 54–62cm head circumference, and each one ships with a black foam sizing-clip insert that attaches inside the sweatband and shrinks the fit by about 2–3cm for smaller heads. That range covers most adult head sizes, but if you're on the smaller end or your hair adds noticeable bulk at the front, the insert is there specifically to tighten things up rather than leaving you with a cap that sits loose or slides back.
How do I care for a cap so it doesn't damage my curls over time?
Wash the cap itself gently and let it air dry — a stiff, sweat-stained, or misshapen cap is rougher on hair than a clean one, and machine washing or drying can warp the brim and shape. Keeping the cap in good condition protects both the cap and whatever hairstyle it's covering.
For Ponyloop caps specifically, the recommended care is hand wash cold and air dry only — no washing machine, no tumble dryer, since heat and agitation can distort the shape and the ponytail opening. This is a general rule worth applying to any structured cap you wear regularly with curly hair: a cap that's lost its shape sits differently on the head and can create more friction and flattening than a fresh one.
Frequently Asked Questions
Does a baseball cap always ruin curly hair?
No. It temporarily flattens or creases curls while worn, especially at the crown, but this isn't permanent damage. How much it happens depends on the cap's fit, how tight it sits, and how the hair is gathered underneath.
What's the difference between a regular cap and a ponytail-hole cap for curly hair?
A regular cap is a closed dome that pushes all your hair up against the inside of the crown. A ponytail-hole cap, like Ponyloop's Original or Vintage styles, has an opening at the back so a ponytail, bun, or braid passes through and rests outside the cap instead of being crushed.
Do ponytail caps come in different sizes for different head shapes?
Most, including Ponyloop's, are one-size designs meant to fit a range of head circumferences (Ponyloop covers roughly 54–62cm) and include a removable insert to shrink the fit for smaller heads rather than offering multiple separate sizes.
How should I wash a cap designed for curly or thick hair?
Hand wash it in cold water and let it air dry. Avoid washing machines and tumble dryers, since heat and agitation can warp the shape and brim, which in turn changes how the cap sits on your head.
If you specifically want a cap that keeps a ponytail, bun, or braid intact rather than flattened, Ponyloop® makes caps built around a back opening for exactly that purpose, currently priced at 24.99€ and sold at ponyloop.com (ponyloop.fr for France) with a 14-day exchange window if the fit isn't right.