How to Wash a Hat Without Ruining It

The short version: hand-wash it. Lukewarm water, a small amount of mild detergent, twenty minutes to soak, a soft brush on the sweatband, then press the water out in a towel and reshape the crown over something round while it air dries. That is the whole procedure for the overwhelming majority of hats — baseball caps, camp hats, snapbacks and dad caps alike — and it takes about ten minutes of actual attention.

What follows is the rest of it: what changes depending on what your hat is made of, why the dishwasher trick you have read about is a bad idea, how to get sweat stains out once they have set, and how to dry a hat without ending up with a warped brim.

Before you wash anything, check the brim

One check decides everything else. Press the brim between your thumb and finger and flex it.

A modern brim has a plastic insert. It bends, springs back, and feels uniformly stiff. Nearly every cap made in the last few decades is built this way, and it can be submerged without a problem.

An older brim may be cardboard. It feels softer, less springy, and sometimes you can find a seam where the layers separate. Vintage caps and cheap promotional hats still turn up with these. Cardboard brims cannot get wet. Water turns the board to pulp, it dries wrinkled and lumpy, and there is no fixing it afterwards. If you have one of these, skip straight to spot cleaning: a barely damp cloth on the fabric, nothing that soaks through.

If you are not sure, assume cardboard and spot clean. You lose very little by being careful and quite a lot by guessing wrong.

How to wash a hat by hand

This is the default method and the one worth learning properly.

1. Fill a basin with lukewarm water. Not hot. Heat is the thing that shrinks cotton, sets stains and softens the glue in a structured crown, and you gain nothing from it.
2. Add a small amount of mild detergent. A teaspoon of liquid laundry detergent, or dish soap in a pinch. Skip anything with bleach or optical brighteners, and skip powder — it does not always dissolve and the grit sits in the weave.
3. Submerge the hat and leave it for 15 to 20 minutes. Most of the cleaning happens here, not in the scrubbing. Soaking loosens salt and body oil out of the fibres so you barely have to work at them.
4. Work the dirty parts with a soft brush. A spare toothbrush is ideal. The sweatband is where the real grime lives, followed by the underside of the brim edge where your fingers grip it. Brush along the weave, not in circles, and use light pressure — you are lifting, not scouring.
5. Rinse until the water runs clear. Leftover detergent attracts dirt and leaves a stiff residue as it dries. This takes longer than you think.
6. Press the water out in a towel. Lay the hat on a dry towel, fold it over, and press. Never wring a hat. Twisting is what breaks the crown’s shape and creases the brim, and unlike dirt, that damage is permanent.

Then go straight to drying, below — a wet hat left to its own devices is a hat that dries the wrong shape.

Can you put a hat in the washing machine?

You can, but treat it as a downgrade rather than a shortcut. It works acceptably on soft, unstructured cotton hats. It is a genuinely bad idea for anything with a stiff front panel.

The problem is agitation. A washing machine works by tumbling and flexing fabric against itself, and the structured front panel on a typical baseball cap is held up by a fused interlining that does not enjoy being folded repeatedly. Come out the other side and the front panel can be soft, rippled or creased in a way that never fully recovers.

If you are going to do it anyway:

• Cold water, delicate or hand-wash cycle, lowest spin speed available.
• Put the hat in a mesh garment bag, or a plastic cap cage if you own one.
• Wash it alone, or with towels — never with anything that has a zip or a hook.
• Take it out the moment the cycle ends and reshape it while it is still wet.

You save perhaps eight minutes over washing it by hand and you accept a real chance of changing the hat’s shape. That trade rarely looks good in hindsight.

Can you wash a hat in the dishwasher?

No. This advice circulates widely — including on pages currently ranking above this one — and it is wrong for three specific reasons.

1. Dishwasher detergent is not laundry detergent. It is formulated to break down food residue on glass and ceramic, and most formulations contain oxygen bleach, enzymes and optical brighteners. On a dyed cotton hat that means fading, and on a dark or coloured hat it can mean visible patchiness after a single cycle.
2. The heated dry cycle deforms the brim. A dishwasher’s drying phase runs far hotter than anything a hat encounters in normal use. The plastic insert in the brim softens at those temperatures, and it re-hardens in whatever shape it happened to be sitting in.
3. A sanitise cycle is worse. It exists specifically to hold high temperatures for longer, which is precisely the condition you are trying to avoid.

The reason the trick spread is that it appears to work: the hat comes out clean. The damage is cumulative and shows up over several cycles as a faded, subtly misshapen hat, by which point nobody connects it back to the dishwasher. Hand-washing takes about the same total effort and does none of that.

Which method for which hat

Material decides the method more than style does.

Hat	Hand wash	Machine	Dishwasher	Notes
Cotton twill (most baseball caps)	Best	Acceptable if unstructured	No	Cold or lukewarm; will shrink slightly in heat
Cotton-poly blend	Best	Acceptable	No	More shrink-resistant and dries faster than pure cotton
Wool	Only method	Never	Never	Cold water, wool detergent, zero agitation, dry flat
Performance / synthetic	Best	Acceptable, cold only	No	Never use heat — synthetics can glaze or shrink hard
Leather patch	Spot clean only	Never	Never	Keep water and detergent off the patch entirely
Cardboard brim (vintage)	Spot clean only	Never	Never	Any soaking destroys the brim permanently

How to get sweat stains out of a hat

Sweat leaves behind salt and protein, and the yellow-brown ring on a sweatband is those two things bonded into the fibre over time. They respond to different treatment than dirt does, which is why a normal wash often leaves the stain looking exactly as it did before.

Work up through these in order and stop when it is clean.

1. Rinse fresh sweat the same day. Cold water, straight through the sweatband. Salt that never dries into the fabric never becomes a stain in the first place. This is the entire trick, and almost nobody does it.
2. Pre-soak set stains in an enzyme detergent. Enzymes break down protein specifically, which is what ordinary soap fails at. Thirty to sixty minutes in lukewarm water with a biological or enzyme-containing detergent does more than any amount of scrubbing.
3. Work a paste into the band. A little detergent worked into a paste, or baking soda and water, applied directly to the stain and left ten minutes before brushing gently with a soft brush.
4. Finish light-coloured hats in the sun. Lay the hat out while still damp. Sunlight has a mild bleaching effect that lifts the last of a yellow ring on white and light hats. Do not do this with dark or brightly dyed hats — it will fade them unevenly.

Never put a sweat-stained hat anywhere near heat before the stain is gone. Heat denatures protein and locks it into the fibre. A hot wash or a spin through the dryer takes a stain that would have lifted and makes it permanent. This is the single most common way a salvageable hat becomes a ruined one.

Drying and reshaping

More hats are destroyed here than in the wash.

Never use a tumble dryer. Never a radiator, a hairdryer, or a car dashboard in summer. Every one of those applies concentrated heat to a brim insert and a fused crown lining, and both of them are shape-holding components that soften when hot and set again when cool.

What to do instead:

1. Press out excess water in a towel.
2. Reshape the crown over something round and roughly head-sized. A folded towel works, so does a large jar, a coffee canister, or a small mixing bowl turned upside down.
3. Set the brim curve by hand while the hat is wet — that is when it is most willing to take a new shape.
4. Leave it somewhere with moving air and out of direct sun. A full dry usually takes overnight.

If a brim has already flattened or gone wavy, you can often recover it. Dampen the brim, curve it by hand into the shape you want, and hold it there while it dries — rolled inside a coffee mug is the classic method. It works because you are re-setting the plastic insert cold and slowly, which is exactly what heat does badly.

Washing a wool hat

Wool follows different rules, and the penalty for getting it wrong is worse than with cotton.

Use cold water and a wool-specific or delicate detergent. Submerge the hat and press it gently — do not rub, do not swirl, do not agitate it in any way. Rinse in water at the same temperature as the wash, because a sudden temperature change alone can shock the fibres. Press the water out between towels and dry flat, reshaped, away from heat.

The failure mode is felting. Agitation plus heat causes the microscopic scales on wool fibres to interlock permanently, and the hat comes out smaller, denser and stiffer than it went in. Felting cannot be reversed. This is also why wool hats should never see a washing machine, even on a wool cycle — the tumbling alone is enough.

Hats with a leather patch

Spot clean only. Do not submerge a leather-patch hat at all.

Water darkens leather, and as it dries it draws the natural oils out, leaving the patch stiffer and more brittle than before. Prolonged soaking can also work its way into the adhesive holding the patch to the front panel and start to lift the edges.

Clean the fabric around the patch with a cloth wrung out until it is barely damp, keeping detergent off the leather entirely. If the patch itself needs attention, wipe it with a dry cloth and treat it occasionally with a leather conditioner — the same product you would use on boots. Let it air dry away from heat, as always.

We make one of these — a dad cap with a leather patch on the front panel — and this is the care advice we would give for any hat built the same way.

How often should you wash a hat?

For a hat in regular rotation, every ten to fifteen wears is a reasonable rhythm. Wash it sooner if it has taken heavy sweat, and always before it goes into storage at the end of a season.

That last one matters more than people expect. Salt left sitting in a sweatband slowly degrades the fibres around it, so a hat stored dirty over winter comes out weaker than it went in. Ten minutes at the end of the season is cheap insurance.

Frequently asked questions

Can I use dish soap to wash a hat?

Yes. Dish soap is a mild surfactant and works fine as a substitute for laundry detergent — use a small amount and rinse thoroughly, because it foams more than you expect. What you should not use is dishwasher detergent, which is a completely different formulation containing bleaching agents.

Can I put a hat in the dryer?

No. The tumbling misshapes the crown and the heat softens the brim insert, which then hardens in whatever position it lands. Air dry over something round instead. A hat takes about a night to dry on its own.

How do I wash a trucker hat?

Hand-wash the front panel as normal and go gently on the mesh back — it is usually polyester and holds very little dirt, so it needs rinsing rather than scrubbing. The foam front on older trucker hats can crease if you fold it, so keep it supported and dry it over a round form.

Will washing shrink my hat?

Cotton can shrink slightly in heat, which is why every step above specifies lukewarm or cold water and air drying. Washed cold and dried at room temperature, a hat should come out the same size it went in. An adjustable strap or snapback gives you room to absorb any small change; a fitted cap does not, so be especially careful with those.

How should I store hats so they keep their shape?

Stack them crown-up rather than crushing them flat, or hang them on a hook by the back strap. Keep them out of direct sunlight, which fades dye over time, and out of a hot car. If you are stacking, nesting one hat inside another supports the crown better than laying them on their sides.

The hats we make

Everything above applies to ours as much as anyone’s. The 5-panel camp hat is a lightweight, low-profile cotton build — hand-wash it and it will take years of it. The dad cap is the spot-clean-only one, because of the leather.

Both are in the camp hats collection. If you want the same treatment for the rest of your kit, we wrote a companion piece on washing outdoor apparel, and there are more sizing and care answers on our FAQ page.