How to wash a baseball cap without ruining its shape

Check how the cap is built

Start with the brim, because it is the part that cannot be repaired. Modern caps almost always have a plastic brim insert that tolerates water. Many older and vintage caps used cardboard, which softens, warps and can fall apart when soaked. Press the underside of the brim and flex it gently: plastic springs back evenly, while cardboard often feels papery, makes a dull sound when tapped and may already show creases. If you cannot tell, treat it as cardboard.

Then look at the crown and the details. Is the front panel stiffened with a buckram backing, as in a structured fitted cap, or does it fold flat like a dad hat? Our guide to types of hats shows the common constructions. Is the fabric cotton, polyester or a wool blend? Wool blends need cool water and minimal handling because heat and agitation mat and shrink wool fibers, a warning New Era gives in its own cap care guide. Leather straps, suede brims and heat applied logos also dislike soaking and heat. Finally, look for a care tag inside the crown; if there is one, our guide to reading care labels explains the symbols, and those instructions come first.

Spot clean fragile caps

For caps with cardboard brims, structured fitted caps and anything with leather or suede, spot cleaning is the safest method, and New Era recommends it as the only method for its structured fitted caps. Brush off dust with a soft brush and use a lint roller to lift hair inside and out. Dissolve a few drops of mild liquid detergent in a bowl of lukewarm water, dip a clean cloth or soft toothbrush, and work on one area at a time with small circles. Wipe away the suds with a second cloth dampened in plain water, blot with a dry towel, and let the cap dry on a form. For a wool cap, a leather trimmed one or a vintage piece you would hate to lose, a dry cleaner is a reasonable alternative, but not every cleaner accepts hats, so call ahead and point out any stains when you drop it off.

Sweat lines on the crown and sweatband respond well to a paste of baking soda and a little water. New Era suggests leaving it for 15 to 20 minutes before scrubbing gently and rinsing it off with a damp cloth. Test any cleaner on the inside of the sweatband first, especially on bright or dark colors. If the sweatband has yellowed, the approach in our guide to removing sweat stains applies here too, as long as you keep the brim dry.

How to wash a hat by hand

For unstructured caps with plastic brims, and for most everyday cotton and polyester caps, hand washing gives a thorough clean with full control. It follows the same logic as hand washing any delicate garment: gentle detergent, the right water temperature, no wringing.

1. 01

   Fill a clean basin with cool to lukewarm water

   Never hot. New Era suggests cool water for wool and nylon, cool to lukewarm for polyester and lukewarm for cotton. Add about a teaspoon of mild liquid detergent and swish to dissolve it.

2. 02

   Pretreat the worst spots

   Dab a drop of detergent directly onto the sweatband and any visible stains. This gives it a head start on body oils, which are the main source of grime and smell in a cap.

3. 03

   Soak for 10 to 15 minutes

   Submerge the cap and let it sit. You should see the water cloud slightly as dirt releases. Colors that bleed noticeably are a sign to shorten the soak and rinse promptly.

4. 04

   Scrub the sweatband and seams gently

   Use a soft toothbrush on the sweatband, along the seams and on stains, with small circles rather than hard strokes. Avoid scrubbing embroidery or printed logos, which can fray or crack.

5. 05

   Rinse until the water runs clear

   Rinse under cool running water, turning the cap so the water flows through the crown, until no suds remain. Leftover detergent can stiffen the fabric and attract dirt.

6. 06

   Press out the water, never twist

   Squeeze the crown gently and press it between towels. New Era warns that wringing or twisting the brim can bend or crack it for good.

Can you wash a baseball cap in the washing machine?

Sometimes. New Era limits machine washing to unstructured cotton or polyester caps and says structured caps, wool blends and anything with a cardboard visor should never go in a washer. If your cap qualifies, place it in a mesh laundry bag or a hat washing cage, a plastic frame that holds the crown in shape during the cycle. Wash on the gentle cycle in cold water with a mild detergent and no bleach, and add only a few light items of similar color rather than jeans or towels, which batter the cap as the drum turns.

A cage reduces the risk of crushing but does not remove it, and even an unstructured cap can come out with a slightly softer crown or a faded front. Take it out as soon as the cycle ends, reshape it by hand while damp and move straight to drying. The dryer is off limits for every type of cap: New Era points out that its heat warps visors, shrinks cotton, mats wool and can melt the adhesive under logos.

Why the dishwasher is a bad idea

Washing a cap on the top rack of a dishwasher is a popular tip, and some detergent makers still suggest it on a light, low heat cycle. The appeal is real: the rack holds the cap upright so it keeps its shape. The problem is everything else a dishwasher is designed to do. Dishwashers run hotter than a cap should ever see, many dishwasher detergents are much harsher than laundry detergent and some contain bleach, and the heated drying phase is exactly the kind of heat that warps brims and melts logo adhesive. You also have no control over where the spray hits, and whatever food residue is in the machine is now in your sweatband.

If you want to know how to wash a baseball cap in a dishwasher safely, the honest answer is that a basin in the sink does the same job with more control. An upturned bowl in the basin holds the crown just as well as the rack, and you choose the water temperature and the detergent. Keep the dishwasher for dishes.

Dry the cap on a form

How a cap dries decides how it looks. While it is still damp, push the crown out from the inside, straighten the seams and set the brim to the curve you like. Then place it over a form so it holds that shape: an upturned bowl, a large coffee canister, a balled towel or a purpose made cap form. New Era recommends drying on a form in a shaded, well ventilated spot. Sun can fade the front panel, and radiators or hair dryers bring back the heat problems described above.

Leave it until the sweatband is completely dry, which can take a day, because a cap put on or stored while the band is still damp starts to smell again quickly. If the finished cap smells musty anyway, our guide on getting smells out of clothes covers what to do. Between washes, wipe the sweatband after sweaty days and store caps on a shelf or hook rather than crushed in a bag, and they will need a full wash far less often.