Therm-a-Rest MondoKing 3D vs Exped MegaMat
In short: The Exped MegaMat is warmer by 1.1 points of R-value; the Therm-a-Rest MondoKing 3D saves 3.0 oz; the Therm-a-Rest MondoKing 3D is 4.25 inches thick against 4.
| Spec | Therm-a-Rest MondoKing 3D | Exped MegaMat |
|---|---|---|
| Approx. price | ~$260 | ~$260 |
| R-value | R 7 | R 8.1 |
| Season band | Winter | Winter |
| R-value standard | ASTM F3340 | ASTM F3340 |
| Weight | 4 lb 6 oz | 4 lb 9 oz |
| R per ounce | 0.10 R/oz | 0.11 R/oz |
| Thickness | 4.25 in | 4 in |
| Pad type | camping mattress | camping mattress |
| Inflation | self-inflating | self-inflating |
| Dimensions | 77 × 25 in | 72 × 25.6 in |
| Packed size | 26 × 10.3 in | 26.5 × 7.9 in |
| Insulation | StrataCore layered open-cell urethane foam | Vertically laminated open-cell foam |
| Top fabric | 50D | not published |
Shaded cells mark the row where one has a measurable advantage. Weight, thickness, girth and shape are left unshaded on purpose: heavier is sometimes tougher, wider is sometimes warmer, and calling a winner on those would be an opinion dressed as a measurement.
What each one does well, and costs you
Therm-a-Rest MondoKing 3D
- 4.25 inches of real foam is closer to a guest-room mattress than to a camping pad, and it holds that loft all night.
- R-value 7 is a winter number — this works on a frozen campground or an uninsulated cabin floor.
- Self-inflates almost completely on its own given ten minutes; the pump/stuff sack tops it off.
- 25 inches wide in the Large and 30 in the XXLarge, so you can actually roll over.
- Fabric and foam are heavy-duty enough that this is a decade-scale purchase rather than a season one.
- Four and a half pounds and a 26-inch roll — this never leaves the vehicle.
- Getting it small enough to fit its own sack takes a knee and some determination.
- $260 is a lot for a camping pad, though it is priced against a decade of use rather than a season.
- The foam core needs to be stored unrolled with the valve open, which takes closet space most people don't plan for.
Exped MegaMat
- R-value 8.1 with four inches of foam — the warmest self-inflating pad here, rated by Exped to roughly -40 °F.
- Vertically laminated foam holds its shape under a hip where a plain foam slab bottoms out.
- A Top-Up pump is built into the mat, so finishing the inflation doesn't need lungs or a separate sack.
- Three widths up to 30 inches, and a Duo version for two.
- Fabric and foam are built to a decade-scale standard rather than a season.
- Four and a half pounds and a 26.5-inch roll: strictly a vehicle mattress.
- $260 to $280, and the Duo and Max versions climb from there.
- Needs to be stored unrolled with the valve open, which takes real closet space.
- Getting it back into its bag after a trip is a two-person job the first few times.