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Sierra Designs Wild Bill 20

rated 4.0 of 5 stars

The Wild Bill 20 has been discontinued. If you're looking for something new, check out the best 3-season synthetic sleeping bags for 2024.

photo: Sierra Designs Wild Bill 20 3-season synthetic sleeping bag

When I bought this bag and first started using it for fall camping, I blamed the fact that I was warm above the waist and freezing below on my advancing age and established tendency to get cold feet. Now after a few years of use I realize the bag is just not designed to keep your feet warm. It's rated by the manufacturer for 20 degrees but is worthless below 50. Last weekend after freezing the first night, I traded off with my 14 year old. He froze all night. This is not because of storage issues because the bag I traded up to was at least 25 years older.

Design: mummy
Fill: polarguard 3d
Temperature Rating: 20

This bag does not live up to its temperature rating...Period. It would be a good bag for summer use only. I used it on a trip to the Yukon last year (45 degree temp) and froze my butt off. Bear in mind I had a partner in a different 20 degree bag, who stayed toasty the whole trip. I ended up wearing wool socks, full fleece, and a stocking cap (with good tent/pad), and I shivered for eight hours each night. After my rough experience I tested a couple of friends' bags with equal temperature ratings. I slept warm in each of those. I would buy this bag only if you intend to use it during warm weather trips only.

Design: Mummy
Fill: 3D
Temperature Rating: 20F
Weight: About 2.5
Price Paid: $90

I have used this bag in the following conditions:

Georgia Summer: Slept on top of it!

Georgia Section of Appalachian Trail for 8 nights: Two nights were very hot, had to stay unzipped, night time temps in 40s. Other nights comfortable to warm, night time temps upper 30s.

Ga Black Rock Mountain: Cozy, night time temps high 20s.

Olympic National Park: Coast of Hoh Head, temps in high 30s, very cozy, Hoh Rain forest trail, temps low 30s, still very cozy.

I am a warm sleeper and this has been a perfect bag for me. I feel I could go into colder climes with ease. (ie 5-20 degrees without too much problem.....)


Design: Mummy
Fill: Polarguard 3D
Temperature Rating: 15-20 F
Weight: 2 lbs 14 oz
Price Paid: $99 at Campmor

No complaints. It's been a good bag for temperate climate weather.


  • I like the ability to strap it to the pad.
  • The size is perfect for me.

I've been using this for nearly 9 years, but only a handful of times. Still looks new and works exactly as I expected. I haven't exactly pushed its limits as I'm a fair-weather backpacker whenever possible. 

Source: bought it new
Price Paid: $90

A bit cold, but the temp was definitely below this bag's comfort rating of 20F. Camped at 4,000ft in January on the AT, where the temp was single digits and the wind blowing at a nice clip. The ground was frozen solid and snow/ice was everywhere. The bag held in heat very well using a Nalgene and boling water as a heater. It is comfortable and does make a great early spring/fall bag.

Design: mummy
Temperature Rating: 20 Farenheight
Price Paid: Around 90 USD

Nice bag. Not as compact as I'd like, probably cuz I'm a bit on the crazy side about stuff like that. But does well in a compression bag. I must say that it has really good touches, like the fleece collar. There are better bags out there with more stuff, but at this price ya cant lose. SD did a good job.

Design: mummy
Fill: polarguard 3D
Temperature Rating: 15 F
Weight: ?
Price Paid: $169, probably can get it cheaper

Excellent bag! Spent the night on top of Mt Rogers with howling 60 mph wind and 20 degree temps. Stayed nice & warm with polartec pants and wool socks! Won't stuff as small as down bags, but hard to beat for the price. Bought this bag on sale after reading many, many positive reviews!

Design: Mummy
Fill: Polarguard 3D
Temperature Rating: 20 F
Weight: 2 lb 15 oz
Price Paid: $119

This bag has been excelent for me. I just spent 9 weeks in the Sierras at ~7000 to 9000 ft. I don't know how it handles the cold weather but I never wear more than boxers when I sleep. Plus it packs small with a compression sack.

Design: mummy
Fill: Polarguard 3D
Temperature Rating: 15 F
Weight: ?
Price Paid: $156

I recently took this bag on a 24 mile section of the AT and was very pleased. I would recommend this bag to anyone who is somewhat serious about backpacking.

Design: mummy
Fill: Polarguard 3D
Temperature Rating: 15 F
Weight: 2 lbs 15 ounces
Price Paid: $143

A very comfortable bag if you are camping in the summer. I do not recommend this bag for even near winter conditions. Otherwise good deal for the money.

Design: rectangular
Fill: polarguard
Temperature Rating: 15 F
Weight: 2lbs. 15oz
Price Paid: $159-169

Your Review

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Regular Long X-Long
Price MSRP: $119.95
Historic Range: $49.95-$149.00
Reviewers Paid: $90.00-$169.00
Weight 3 lb 9 oz / 1600 g 3 lb 12 oz / 1700 g 4 lb 0 oz / 1800 g
Fill Weight 2 lb 3 oz / 990 g 2 lb 5 oz / 1000 g 2 lb 8 oz / 1100 g
Temperature Rating 20° F / - 7° C 20° F / - 7° C 20° F / - 7° C
EN Comfort 34° F / 1° C 34° F / 1° C 34° F / 1° C
EN Lower Limit 25° F / - 4° C 25° F / - 4° C 25° F / - 4° C
EN Extreme - 6° F / - 21° C - 6° F / - 21° C - 6° F / - 21° C
Fill HeatSync Synthetic HeatSync Synthetic HeatSync Synthetic
Shape Mummy Mummy Mummy
Max User Height 6 ft / 180 cm 6 ft 6 in / 200 cm 7 ft 0 in / 210 cm
Shoulder Girth 62 in / 157 cm 64 in / 160 cm 68 in / 170 cm
Hip Girth 58 in / 147 cm 60 in / 150 cm 66 in / 170 cm
Foot Girth 40 in / 100 cm 42 in / 110 cm 46 in / 120 cm
Price $119.95 USD $129.95 USD $139.95 USD

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