Analysis
No Free Loft
Four camp pillows, four fill technologies, and an exchange rate that runs from 4.9 inches of loft per 100 grams down to 1.5. None of them escape the trade.
We compared four camp pillows this week. They use four different fills: bare air, air with a memory foam top, solid urethane foam, and an air cell under a thick foam layer.
Four technologies sounds like four different answers. Divide loft by weight and it turns into one continuous line.
| Pillow | Fill | Loft | Weight | Loft per 100 g |
|---|---|---|---|---|
| Klymit Pillow X Base | Air only | 3.5 in | 71 g | 4.9 in |
| Sea to Summit Aeros Premium | Air + memory foam | 4 in | 104 g | 3.8 in |
| Therm-a-Rest Compressible Cinch | Urethane foam | 5 in | 230 g | 2.2 in |
| NEMO Fillo | Air + thick foam | 4 in | 265 g | 1.5 in |
More than a factor of three between the ends, and the ordering is not about brand, price or cleverness. It is about how much of the thickness is being held up by air.
Air is free volume
That is the whole mechanism. Air weighs essentially nothing, so an inflatable pays only for fabric and a valve and gets its loft for nothing. Foam has to physically occupy the space it holds open, so every inch costs grams in direct proportion.
Which is why the pure inflatable tops the table and the pure foam pillow sits near the bottom while being, by some distance, the nicest one to sleep on.
The interesting case is the one that pays twice
Look at the bottom row. The NEMO Fillo has an air cell and a thick foam layer, and it returns 1.5 inches of loft per 100 grams, a third of what the bare inflatable manages.
It is carrying the fabric, valve and baffles of an inflatable plus the mass of foam thick enough to matter, and getting the loft of neither. At 265 grams it weighs more than the solid foam pillow in its smallest size and delivers an inch less thickness than it. It is a genuinely comfortable pillow. It is just paying two bills for one room.
Compare that to the row above it. The Sea to Summit is also a hybrid, and it returns 3.8, close to the pure inflatable. The difference is that its foam layer is thin, a memory foam top rather than a thick cushion. It spends a small amount of mass to fix the one real complaint about bare inflatables, which is that they feel taut and squeak against a sleeping bag, and it keeps almost all the efficiency.
So hybrid is not the problem. Thick foam over full air is the problem.
Nobody publishes the useful number
Loft per gram appears on no product page in this category. Both inputs usually do, with loft listed as thickness and weight as packed weight, so the division takes about ten seconds. It just has to be your ten seconds.
This is a recurring shape. We have written about specifications that contradict themselves and specifications that go missing entirely. This is a third kind: everything you need is published, correctly, in the right units, and the comparison that matters still requires you to do arithmetic nobody has done for you.
It is the most benign of the three and the easiest to fix. Divide one number by the other and a category that looked like four competing technologies resolves into a single line you can just read your position off.
The rule that falls out of it
Decide your loft from how you sleep, not from a budget. Side sleepers need 4 inches or more to keep the neck straight; back sleepers are fine with less. Then buy the lightest pillow that delivers it.
For most people on foot that means an inflatable with a thin foam top, which is where the comparison landed. For anyone who is not carrying the thing more than a few metres from a car, ignore all of the above and buy the solid foam pillow, because the weight penalty is free and it is the most comfortable object in the category by a distance that the arithmetic does not capture.
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