CLO — what to wear today in Paris
low
3 m/s wind · 13 % rain
Paris
Wed 10 Jun
Roland · forecast 16:31
HOODIE. JEANS. GO.
0.90 CLO. THE PHYSICS HAS SPOKEN, CHAMPION.
THE GREY HOODIE HAS BEEN ACTIVATED. TRUST THE LAYERS.
- ▸DRY MORNING, WET 16H. RAIN AT 65% — THE WATERPROOF RIDES ALONG ALL DAY.
- ▸UV 6 TODAY. SUNGLASSES. YOU'LL LOOK INCREDIBLE.
Your day · tap a segment
RUNS 0.3 CLO WARM — CARRY THE TOP LAYER, WEAR THE CONFIDENCE.
The day · drag to scrub
The core — desk-proof, worn all day · 1.18 clo
- 0.08
Black t-shirt
base
- 0.34
Grey hoodie
mid layer
- 0.36
Grey lambswool sweater
mid layer
- 0.24
Black jeans
legs
- 0.10
Brown leather boots
feet
+ the shell — for outside · 0.36 clo
- 0.36
Navy rain shell ☔
outer
Show me the math
Your body walking produces 2.5 MET × 58.2 W/m²; about 78 % of it leaves through your clothes (the rest: breath + sweat) → 113 W/m².
Insulation needed to lose exactly that at 13 °C:
I_total = (33 − 13) / (0.155 × 113) = 1.15 clo
The air film around you insulates too, but 3 m/s of wind erodes it: I_air = 0.7 / (1 + 0.5 × 3) = 0.26 clo
Target = 1.15 − 0.26 = 0.90 clo
The desk is the unit's own definition: 21 °C, seated, still air → 1.04 clo. That's what the core is sized for.
Assumptions and what they get wrong: how it works.