Clean or replace your boot insoles?

Wash first. It costs nothing, it takes ten minutes of hands-on time, and for most boots it is the whole answer. The insole is the wettest component in the boot and the slowest to dry - foam and fabric, compressed against the sole, with no airflow underneath - so it is where the bacteria live and where the smell is actually coming from.

Superfeet publishes the method for its own insoles and it generalizes fine: use mild soap and warm water, a soft-bristle toothbrush if needed, rinse well, remove excess water with a soft towel, and allow to air dry but avoid heat sources. The same page is blunt about the shortcut: “DO NOT MACHINE WASH OR DRY: The results aren’t pretty.”

So the real question is not how to wash them. It is when washing has stopped being the right move.

The decision, in one table

When washing is the right call

If the insole still has structure - press the heel area with a thumb and it springs back - and the only problem is smell, wash it. You are removing the substrate the bacteria are feeding on, and a clean insole that dries fully is a genuinely different environment from the one that produced the smell.

Two details do most of the work. First, wash both and rotate: if you own a second pair of insoles, the boot never receives a damp footbed again, and that single change does more for odor than most deodorizers. Second, dry them away from heat. Superfeet says air dry and avoid heat sources; the same logic that applies to leather applies to a foam footbed, which will curl and delaminate if you park it on a radiator.

Allow a full day. An insole that goes back in damp restarts the problem, and this is the one component that will still be wet long after the boot feels dry - drying boots overnight covers the setup.

When it is time to replace instead

The foam has packed down. This is the most common and the easiest to check. If the heel area stays compressed after you press it, the cushioning is gone and no amount of washing brings it back. Superfeet publishes a working figure for its own insoles: around 500 miles or 12 months, with the caveat that it varies by weight, biomechanics and how often they are worn. That is one of the very few published replacement intervals in footwear care, and it is worth using as a baseline even if your insoles are a different brand.

There is growth in the foam rather than on it. This is the case where washing genuinely does not work, and the reasoning is not ours - the EPA notes that mold can grow on or fill in the empty spaces and crevices of porous materials, so the mold may be difficult or impossible to remove completely. A foam footbed is about as porous as household objects get. Surface mold on a firm insole may wipe off; a bloom through open-cell foam is a replacement. What to do about the boot itself is in the mold and mildew removers roundup.

It has absorbed a solvent. Diesel, gasoline, kerosene, or anything from a farm floor. An insole is the most absorbent part of the boot and it will hold a contaminant long after the leather has aired out. Replace it rather than washing it, and read fuel and chemical smells in boots before you decide the boot itself is fine.

Four checks, in order

Take the insole out and run these before deciding. They take about a minute between them and they answer the question more reliably than the smell does.

1. Press the heel area with a thumb. If it springs back, the cushioning is alive and this is a washing job. If it stays compressed, the foam has packed down and no amount of washing restores it.
2. Flex it and look at the underside. Cracks across the forefoot or a support layer that has split or gone white along a stress line means the structure has failed. That is a replacement regardless of how it smells.
3. Check for separation at the edges. Most insoles are a top fabric bonded to a foam body. Once those layers start lifting they will keep lifting, and the gap between them holds water you cannot get out.
4. Smell it away from the boot. This matters more than it sounds. If the insole is out of the boot and the boot still smells, the reservoir is the lining rather than the footbed, and replacing insoles will not fix it - that is a different job.

How to wash them, step by step

This follows Superfeet’s published method for its own insoles, which is the only manufacturer procedure we could source for footbeds. It generalizes safely to most foam and fabric insoles.

1. 01

   Take them out and knock the grit off

   Loose dirt first, dry. Washing grit into a foam surface grinds it in rather than removing it, and grit is what wears the top fabric through.

2. 02

   Mild soap and warm water, by hand

   Superfeet specifies mild soap and warm water, with a soft-bristle toothbrush if needed. Not detergent, not a scouring pad, and not hot water - the adhesive holding the layers together is the weak point.

3. 03

   Rinse well

   Soap residue left in foam attracts dirt and can irritate skin. Rinse until the water runs clear, and give the heel cup extra attention because it holds the most.

4. 04

   Blot with a towel, then air dry

   Press the water out with a soft towel rather than wringing, which delaminates the layers. Then air dry, and give it a full day - foam holds water long after the surface feels dry.

5. 05

   Away from heat, without exception

   Superfeet says to avoid heat sources. A radiator curls the insole and can shrink the top cover away from the foam. The same rule that applies to the boot applies to the footbed.

If the smell survives a proper wash and a full dry, wash them once more before concluding it has failed. What does not survive two attempts is generally in the material rather than on it, which is the replace case.

The insole is not always the culprit

Worth ruling out before you spend an evening on it. The other reservoirs in a boot are the lining - especially textile linings around the toe box, which hold water in the weave - and the foam padding under the tongue and collar. Neither comes out, and neither is helped by washing the footbed.

The test is the one above: get the insole out, let both dry properly, and smell them separately. If the insole is fine and the boot is not, you are dealing with the lining, and the approach is different - moisture control and time rather than a replacement part. That is covered in how to get the smell out of boots.

What a replacement actually costs you

Insoles are the cheapest structural component of a boot and the only one designed to be replaced. Set against the price of the boots, replacing a twelve-month-old footbed is close to free - which is why the answer to “should I replace the insoles or the whole boot” is almost always the insoles.

There are three broad routes. A structured insole such as the Superfeet All-Purpose gives you something that holds its shape and dries independently, at the cost of taking real volume out of a snug boot. A cheap cushioning insole is the right answer if the plan is to buy two pairs and rotate them, accepting that the foam compresses within months. A ventilated footbed sits between the two and is worth considering in boots with no lining ventilation at all.

Which of the three suits your feet is a different question from which suits your moisture problem, and the insoles roundup ranks them on the moisture side.

The rotation argument, which beats both

The highest-value move here is not washing and it is not replacing. It is owning two footbeds for boots you wear daily, so that a dry one goes in every morning while the other one dries. That is a one-time purchase of the cheapest thing in the boot, and it removes the condition that creates the smell in the first place.

For anyone whose boots genuinely do not get a rest day - which is most people who work in them - this is the whole strategy, and it is laid out with the rest of the routine in how to stop work boots smelling.

The short version

Wash first, by hand, with mild soap and warm water, air dried away from heat. Replace when the foam has packed down, when there is growth through it, when it has taken up a solvent, or at roughly 500 miles or a year. And if the boots are worn every day, buy a second pair of insoles rather than choosing between the two.