How much does a sleeping bag liner increase warmth?

[Rick.in.AZ]

I'm looking to buy a lighter bag for summer use, and plan to use a liner for colder stretches.

The liner manufacturers claim upwards of 10* F added comfort range for the silk liners when using them.

Those of you who have used them, what have you found?

Reason is - I have a 20* bag now - too much for my TransAm plans for next summer, but a 45* bag while perfect for Kansas to Virginia may be marginal for the Cascades and Rockies. But if a silk liner really adds 10*, then a 45* bag will be perfect for these times.

Is this valid claims or are these modern $50 snake oil items?

[staehpj1]

I have a hard time putting a number on it, but If I am chilly and add my silk liner the difference is definitely noticeable.  I have been chilly, added the liner and been comfortable.  Not sure if that equates to 10 degrees or not.  You can also sleep in tights and a thick shirt to add a good bit of warmth, and you are probably carrying them anyway.

Oh and one other thing for me it helps a bunch to double up on the socks.

Remember that a lot depends on the bag.  Unless they are using EN numbers you will find huge variation in bags that are nominally listed as the same.  That difference can easily be more than 10F.

[pkeibel]

I used to teach mountaineering for the ski patrol and what I told people is test first. What may add 10 degrees for one may not for another

[Pat Lamb]

For me, a silk liner adds about 15F to the temperature range.  In my case, it takes a 30 year old 20F bag back down to about 20F.  (It wasn't really stored correctly in the interim.)

[John Nelson]

I agree that it's noticeable. I was camping at 10,000 feet once and woke up at 3 a.m. shivering and too cold to get back to sleep. I added my silk liner and slept comfortably for the rest of the night.

[Rick.in.AZ]

Thanks guys.  Your experience seems to validate the claims.

Sounds like the liner + 40 or 45* bag is the answer.  Then in effect I'd have a 10* bag (my existing 20* bag + a liner), a 20* bag (existing bag alone), a 32* bag (new 45* bag + liner), a 45* bag (new bag), and a 60* bag (just the liner).  Lots of options

[staehpj1]

FWIW, I really like the Mountain Hardware Phantom 45.    It packs tiny and I find it warmer than the name suggests.  Specs include:

• Weight - 17 ounces
• Loft - 3 in / 8 cm
• Stuff Size - 6 in / 15 cm
• EN Rating: T-Limit - 32 F / 0C
• EN Rating: T-Comfort - 41 F / 5C

I find mine warm down to freezing with no extra clothing or liner (other than running shorts, tech tee, and socks).  I do tend to sleep way warmer than many folks do though so test before you go or be prepared with extra layers.

[bogiesan]

Thanks guys.  Your experience seems to validate the claims. Sounds like the liner + 40 or 45* bag is the answer.  Then in effect I'd have a 10* bag (my existing 20* bag + a liner), a 20* bag (existing bag alone), a 32* bag (new 45* bag + liner), a 45* bag (new bag), and a 60* bag (just the liner).  Lots of options

I do not do self-supported touring so my gear list is a bit, umm, luxurious. Most of my touring is in Idahho where a week's traveling can take us from desert at 1500 feet to 9,000 feet alpine canyons in a day. Nighttime temps on the desert might be 60-75F but 25-35F the next. So have learned to I carry two down bags from Marmot, a one-pounder and a two-pounder. I also carry a silk liner. This gives me a wide range of comfort levels and the silk liner has kept the down bags quite clean.

If I were carrying my own gear, I'd go for the 2-pound bag, a silk liner and a set of silk sleepwear.

BTW: Down is queen in Idaho's climate. If I'm doing Cycle Oregon, I know we'll see rain on at least two days. I take the one-pound down bag, a 2-pound synthetic and the silk. The down bag is double-bagged in waterproofness and compresses to the size of football.

[Rick.in.AZ]

@bogiesan - Down is a given.  while it does have to be kept dry, it is lighter for a given warmth, but perhaps more importantly, it has a much broader temperature comfort range than poly.
@ staehpj1 - yes, I hear lots good about the phantom 45. And I found a site with it for $220.  I'll likely bite at that price.
My tour collection is growing 

[staehpj1]

@ staehpj1 - yes, I hear lots good about the phantom 45. And I found a site with it for $220.  I'll likely bite at that price.

It is a nice bag if it is in the warmth range that suits you for the conditions.  I have found it to be very versatile.

[Pat]

Also,  it's easier to wash and dry a liner on the road than an entire bag.  Just sayin'

Pat

[staehpj1]

Also,  it's easier to wash and dry a liner on the road than an entire bag.  Just sayin'

That is one way folks use liners, to protect their down bags.  Me I only use the liner alone on really warm weather, or to supplement the bag in really cold weather so the washability isn't a huge issue.  Besides I very seldom wash my sleeping bags and am extremely unlikely to do so on tour unless I start living on the bike year round.

[awbikes]

Opinions and personal experience vary. As winter is approaching you will have plenty of cool weather to experiment in your back yard with a liner, layering clothing etc. Your personal experience will teach you the most. Don' forget to use your tent as this will add a few degrees warmth. In any event a bag liner is worth the expense as it will not only add warmth but protect your bag from dirt/grime.

[Rick.in.AZ]

As winter is approaching you will have plenty of cool weather to experiment in your back yard

Good point. Though I live in a condo with just a small balcony - but doable. And here in the valley of the sun, mornings at or below freezing are infrequent    None the less - a very good suggestion. And I can test how I do stuffed, vs. hungry. I know that makes a difference too.

[dwboca]

I use a silk liner and it helps but what really saved me once when we encountered unexpected freezing conditions was one of those "emergency blankets" that fold up to wallet size and looks metallic.  I put it around my feet and pulled it up as far as it would go and then wrapped it under me.  It really kept in the warmth.  I always carry one and hope I won't need it because I hate being uncontrollably cold at night.