How Often Should You Wash Workout Clothes? (Merino vs Synthetic)

“Do I really need to wash these after every workout?” is one of the most common questions in activewear — and the honest answer is: sometimes yes, sometimes no.

What matters most is fabric behaviour, not guilt. Some fabrics hold onto sweat oils and odour compounds and will smell “clean” until they warm up again. Others stay wearable longer without turning into a bacteria trap.

The simple rule (most people can follow this)

High sweat + tight synthetic (leggings, sports bras, polyester tops): wash after each wear.
Light sweat + loose layers (outer tees, warm-ups): you can often rewear once if it dries fully and doesn’t smell.
Merino: many people can rewear more times because it’s naturally odour-resistant — as long as you dry it between sessions.

If you’ve ever had gear that smells fine on the hanger but stinks as soon as you move, read: Why Workout Clothes Smell — Even After Washing.

When you can rewear workout clothes (without it being gross)

You can usually rewear a piece if all three are true:

It dried fast (not stuffed damp in a bag or hamper).
No active odour (do a quick sniff test at the underarms/crotch/waistband).
No heavy skin contact from high-sweat zones (sports bras/underwear/very tight leggings are less “rewear-friendly”).

Big rule: if it’s damp for hours, don’t rewear it. Damp is the accelerant.

Why synthetic activewear usually needs more washing

A lot of synthetics are great at handling moisture in the moment, but they also tend to:

Hold onto sweat oils that detergent doesn’t fully remove
Trap odour compounds that “reactivate” with heat + movement
Build up residue (from deodorant, detergent, softeners) that makes smell worse

That’s why many people end up stuck in the cycle of “wash → smells okay → workout → smells instantly”. If that’s you, this is the practical fix: How to Get Smell Out of Workout Clothes (And Stop It Coming Back).

Why merino can mean fewer washes (and less laundry stress)

Merino’s advantage isn’t “magic”. It’s that it tends to be naturally odour-resistant, so you’re not relying on chemical anti-odour treatments to mask a material problem.

For a deeper breakdown of why this becomes a real performance advantage (and time advantage), read: Why Merino Activewear Needs Less Washing.

If you’re training in heat/humidity where stink usually spikes, this connects too: Merino in Heat & Humidity.

How to reduce how often you wash (without getting smelly)

Dry gear immediately after training (hang it; don’t ball it)
Skip fabric softener (it can trap oils and reduce breathability)
Rotate pieces so nothing gets repeated while still damp
Air between wears (especially for merino and outer layers)

For a safe care routine (and avoiding shrinkage), use: Washing, Shrinking & Care.

Want less washing, less smell?

Explore the Estroni Merino Guide and find the pieces that match your training.

Go to the Merino Guide →

Quick FAQ

Should I wash workout clothes after every wear?

If it’s tight synthetic and you sweat a lot, yes. If it’s a loose outer layer and it dried fully with no odour, you can often rewear once.

Is it okay to rewear merino activewear?

Often yes, especially if it dries quickly and doesn’t smell. Merino tends to be naturally odour-resistant, which is why many people wash it less frequently.

Why do my clothes smell as soon as I start sweating?

That’s usually trapped odour compounds and residue reactivating with heat and moisture — very common with synthetics. Use: this explanation and this fix routine.