One weighs nothing. The other works when wet.
Verdict
A mylar sheet reflects radiated body heat, packs to nothing and costs almost nothing, but it traps moisture, tears easily and does nothing once it is torn. Wool insulates even when damp, lasts decades and is heavy. Carry mylar in every bag and vehicle because it is free weight; keep wool at home and in the car for actual warmth.
~$40
Check Fire Retardant Wool Blanket, 66 x 90 in Price~$12
Check Emergency Mylar Blankets, Multi-Pack Price| Fire Retardant Wool Blanket, 66 x 90 in | Emergency Mylar Blankets, Multi-Pack | |
|---|---|---|
| Insulates when wet | Yes | No, traps condensation |
| Weight | Heavy | Almost none |
| Durability | Decades | Single use in practice |
| Packs small | No | Yes, pocket sized |
| Doubles as a ground sheet | Poorly | Yes |
| Fire resistance | Wool is naturally resistant | Melts |
You are equipping a home or a vehicle. Wool keeps insulating when damp, which is the property that matters in real cold, and it survives being used repeatedly rather than tearing on the first sharp edge.
Check Fire Retardant Wool Blanket, 66 x 90 in on Amazon
You are filling a bag where every ounce counts. Mylar reflects radiant heat effectively for its weight and costs so little that there is no reason not to have several. Understand its limits: it does not breathe, so you get wet from the inside.
Check Emergency Mylar Blankets, Multi-Pack on Amazon
They reflect radiated heat, which is a real mechanism and useful. What they do not do is insulate against conduction or handle moisture, so they are a stopgap rather than bedding.
Being wet, then wind. Staying dry matters more than any single insulation choice, which is why a waterproof layer often outranks a warmer one in a kit.
Yes. A car in winter is a survival shelter if you slide off the road, and wool works regardless of whether the engine runs. It is one of the highest value items to keep in a boot.
Comparison based on published manufacturer specifications and the general consensus of owner reports. We have not tested these units side by side. Confirm current prices and specifications before buying. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you.
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For informational purposes only. Follow guidance from FEMA and local authorities.