If you've ever tried to sleep in a hammock and woken up with a cold back, you've met the enemy: the cold air moving underneath you crushes your sleeping bag's insulation flat, so it can't keep you warm. A top quilt won't fix it. The answer is a hammock underquilt — an insulated layer that hangs below your hammock, hugging the bottom without getting compressed. It's the single biggest upgrade to a cold-weather hang.
We're a little biased here: Jacks R Better invented the hammock underquilt back in 2004, and we've been hand-sewing them ever since — in Virginia through 2018, and in Pennsylvania since. Below is an honest guide to choosing the right one — what to look for, and which JRB underquilt fits your setup best.
How to choose a hammock underquilt
Before the picks, here's what actually matters:
Temperature rating. Match it to the coldest night you'll realistically face — and don't be shy about sizing warmer than you think you need. Here's the key difference from a top quilt: you won't overheat from an underquilt that's rated too warm. Because it hangs beneath you instead of over you, extra warmth simply goes unused — you regulate temperature with your top quilt, not the underquilt. So erring colder costs you nothing but a few ounces. A 40° quilt is a summer piece; 20° covers most three-season hangs; 0° is true winter.
Fill power and shell. Higher fill-power down is warmer for its weight and packs smaller. Our dedicated underquilts use 850FP down behind a wind-resistant Ion 1.1 shell; the ultralight multi-function models step up to 1000FP down with a 10D (0.67 oz/yd²) shell for backpackers counting every gram.
Dedicated underquilt vs. multi-function. Our Mt Washington and Greylock models (and the Nest line) are purpose-built as underquilts: dual differential contoured radial baffles let the down loft fully and eliminate cold spots, and the size is dialed in specifically for hanging beneath a hammock — the best pure-underquilt warmth and fit. Our multi-function quilts trade a little of that underquilt-specific optimization for versatility: they also work as a top quilt, ground quilt, or wearable wrap.
Weight vs. budget. Standard down is warm, durable, and easier on the wallet. Ultralight down and shells shave serious ounces for thru-hikers, at a higher price. Pick based on how far you carry it.
Coverage: full-length vs. 3/4. A full-length underquilt covers you head to toe. A 3/4-length quilt saves weight by covering your core and legs while you tuck a pack or spare layer under your feet — a favorite trick of gram-counters.
Hammock compatibility. Every JRB underquilt fits any hammock — they hang underneath on our shockcord suspension, tuned specifically to dial in the perfect hang quickly and easily, so you're never locked to one brand. If you run a bottom-entry Hennessy, our Nest models are designed specifically for that setup.
The best hammock underquilts, by use
Best overall three-season underquilt: Mt Washington 3 (20°)
For most hangers most of the year, a full-length Mt Washington 3 20° ($289.95) is the sweet spot — warm enough for spring through fall, dead-simple to rig, and built to last. Like all our dedicated underquilts, it uses dual differential contoured radial baffles and an underquilt-specific cut, so it lofts fully and fits close with no cold spots. If you buy one underquilt, this is it.
Best winter underquilt: Mt Washington 4 (0°)
When the temperature drops into the teens and single digits, step up to the Mt Washington 4 0° ($359.95). Full-length 0° warmth with 850FP down and the Ion 1.1 shell — the quilt that earned its name on the coldest peak in the Northeast.
Best 3/4-length: Greylock 3 (20°) & Greylock 4 (0°)
Want to trim weight and bulk without going fully ultralight? The Greylock 3 20° ($269.95) and Greylock 4 0° ($309.95) are 3/4-length: cover your core and legs, slide a pack or spare layer under your feet, and carry less than a full-length quilt.
Best for bottom-entry Hennessy hammocks: The Nest (20°) & Winter Nest (0°)
Every JRB underquilt fits a Hennessy, but if you run a bottom-entry Hennessy, the Nest models are purpose-built for it. The Nest 20° ($329.95) handles three-season nights; the Winter Nest 0° ($399.95) takes you into deep cold — both designed specifically for bottom-entry Hennessy hammocks.
Best do-it-all pick (underquilt + top quilt + more): the Multi-Function line
If you want one piece that pulls double duty, our multi-function quilts work as an underquilt, a top quilt, a ground quilt, or a wearable wrap. The Shenandoah 40° ($189.95) is the warm-weather entry point; Hudson River 20° ($279.95) and Old Rag Mountain 0° ($339.95) cover three-season and winter. Browse them all in Multi-Function Quilts.
Best lightweight underquilts: the Ultralight Multi-Function line
For the lightest underquilt, period, go ultralight multi-function. The Shenandoah Ultralight 40° ($329), Hudson River Ultralight 20° ($459), and Old Rag Mountain Ultralight 0° ($599) use 1000FP down and a 10D (0.67 oz/yd²) shell to hit the lowest weight without giving up warmth — the top pick for thru-hikers and gram-counters. Browse them in Multi-Function Quilts.
Quick pick-by-temperature
- Summer / 40°: Shenandoah 40° (multi-function, $189.95)
- Three-season / 20°: Mt Washington 3 (full-length) or Greylock 3 (3/4-length)
- Winter / 0°: Mt Washington 4 (full-length) or Greylock 4 (3/4-length)
- Bottom-entry Hennessy: The Nest (20°) or Winter Nest (0°)
- Lightest / ultralight: the Ultralight Multi-Function line (Shenandoah UL, Hudson River UL, Old Rag UL)
The bottom line
The best hammock underquilt is the one matched to your coldest night. Every JRB underquilt fits any hammock, so mostly it comes down to temperature and weight: for most people, a 20° full-length like the Mt Washington 3 is the do-everything choice; winter campers want a 0°; bottom-entry Hennessy owners like a Nest; and if you want the lightest option, go ultralight multi-function. Every one is hand-sewn in Pennsylvania and built to keep the cold air where it belongs — beneath the quilt, not beneath you.
Shop all hammock underquilts →
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