Sleep-System Tools & Calculators
The question every backpacker asks is "what bag and pad do I actually need?" These free, interactive tools answer it as a system — enter your overnight low and get the bag ISO Comfort rating AND the minimum pad R-value, or compare candidates on warmth-to-weight to see how light you can go. Each carries a "How this is calculated" note: ratings are ISO 23537 lab figures and R-values are ASTM F3340 lab figures, real-world warmth varies, and no rating is a survival guarantee. No review claims — just the specs.
Bag + Pad Temperature / R-Value Matcher
Enter your destination overnight low and sleeper type to get the bag ISO Comfort rating AND the minimum pad R-value you need — as a paired system, because a warm bag on a cold pad still sleeps cold.
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Warmth-to-Weight Comparator
Enter candidate bags or pads (rating and packed weight) to get a warmth-to-weight score, so you can see how light you can go without giving up warmth.
Open the calculator →