Sleeping bag warmth ratings

[welland99]

Been looking for some sleeping bags this week to go camping this half term. Warmth ratings are the most confusing thing ever. Is there a universal standard system for comparing the warmth of different bags.

I thought there was, as they all show a season rating (1,2,3,4,etc..) and they all show extreme temperature and comfort temperature.

However, very confused about how two different bags can:
both be rated 3 season
both show min. comfort temperature of -2C,
but
one is much thinner and lightweight than the other. And,
the thinner one has a max. comfort rating of 10c, whilst the thicker one has a max comfort rating of 25C


What are your thoughts?

 

[welland99]

Forgot to say: The thin bag has 200gsm microfiber filling and the thick bag has 300gsm hollowfibre.

Is microfibre known to be better at keeping you warm in cold temperatures and worse for keeping you cool in warm temperatures (weight for weight)?

 

[crockers]

Would you actually use a sleeping bag in 25C weather?

 

[MOCAŠ]

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[finisterre]

Three season is pretty warm, I would be tempted by something thinner.

I have a comfort 0-17C and it is generally too warm May to September.

Those ratings you quoted made no sense to me either.

 

[Satch]

Warmth ratings in terms of "Seasons" are ******.

Explained here but there is no single right answer: too many variables!

Guide To Sleeping Bags