A close look at two sleeping bags buyers cross-shop. The Spark 30F leans on warmth while the Classic 30F answers with low weight, so the pick comes down to which you value.
| Sea to Summit Spark 30F | Zpacks Classic 30F | |
|---|---|---|
| GearScore | 85✓ | 63 |
| Comfort rating | 39 °F✓ | 40 °F |
| Weight | 17.4 oz | 13.8 oz✓ |
| Warmth-to-weight | 6.3 /100g | 7.7 /100g✓ |
| Packed size | 4.5 L | n/s |
| Fill power | 850 FP | 950 FP✓ |
| Price | $449 | $419✓ |
| Fill | Down | Down |
| Style | Bag | Bag |
| Shape | Mummy | Semi-rectangular |
Highlighted cells mark the better spec: Spark 30F in blue, Classic 30F in amber. A blank spec is never counted as a win. A lower comfort rating in °F means a warmer bag, so the warmer bag takes that row. GearScore is the overall rating (0 to 100); re-weight it on the full bag comparison. Prices are current MSRP.
Put the Sea to Summit Spark 30F next to the Zpacks Classic 30F and the trade-offs are clear. The Spark 30F wins on warmth, and the Classic 30F pushes back on low weight and warmth-to-weight.
The Spark 30F is warmer (rated 39°F vs 40°F). The Classic 30F is 4 oz lighter, stronger on warmth-to-weight, and higher fill power (950 vs 850). On the default GearScore the Spark 30F leads 85 to 63.
Pick the Spark 30F if you care most about warmth, which makes it the better call for colder nights and shoulder-season trips. Pick the Classic 30F if low weight and warmth-to-weight matter more to you, or you are focused on counting grams on long miles.
The Sea to Summit Spark 30F. It is warmer (rated 39°F vs 40°F) than the Classic 30F.
The Zpacks Classic 30F. It is 4 oz lighter than the Spark 30F.
The Sea to Summit Spark 30F, 85 to 63 on the default algorithm. You can re-weight the factors to match your trip.
It depends on your priorities. Go with the Spark 30F for warmth, or the Classic 30F for low weight. The spec table above shows exactly where each wins.