TOG RATINGS, WARMTH and QUALITY
Some information from the internet (italics added)
What's a Tog Rating? Does it tell you how warm a quilt will be or how good the quality of a quilt is?
Not really. It helps, but it is far from a complete answer.
A Tog is a unit of measurement for the warmth of a quilt. The trouble is that tog ratings are calculated in a laboratory using a new quilt on a flat surface. Now you are not a flat surface, and how the quilt drapes round you is also very important.
After you've slept under it a few times your quilt isn't new, and poor quality quilts lose their tog ratings fast, particularly if they're washed. So a tog rating is at best only a rough guide to how warm you'll be.
It is true that a very cheap quilt will have a low tog rating, and will be made of poor quality materials. But of itself the tog rating tells you nothing about a quilt's quality
So, when you're choosing a quilt, by all means take a note of the tog rating. But if you want a good buy, don't stop there.
What does the TOG rating mean?
The tog rating describes the warmth or "Thermal Resistance" of a product and is widely used in the UK to explain warmth levels of duvets. Grobags are Tog tested to conform to BS4745:1990. When testing we need to allow for a margin of error of 0.5 togs on the upper side. This means that our 2.0 tog Grobags will not exceed 2.5 togs, in line with current UK guidelines.
Which tog rating?
British Standard tog ratings range from 4.5 (summer weight duvet) to 15.0 (suitable for very cold winters). 13.5 tog is the most commonly used tog in Ireland and the UK. However, with increased usage of central heating, 12.0 and 10.5 togs are becoming more popular.
Choose your baby's sleeping bag according to season so that he or she stays comfortably warm and does not overheat. Bags are given a tog rating according to the warmth they provide. In Winter a first-size baby
sleeping bag should not be more than 4 tog. 2.2 tog is the average (this compares with an adult winter duvet which rates 13 tog). In summer you'll need a sleeping bag with a lower tog rating; baby sleeping bags go down to a minimum of 0.5 tog (the equivalent of two sheets). When using a new bag, check your baby to ensure that the design and weight do not lead to overheating, and make sure that the room in which your baby sleeps is not too warm (the ideal room temperature for a baby is 18 degrees C/65 degrees F).
The British "tog" value is the international standard measurement of all blankets' thermal effectiveness (how well it keeps you warm). The higher the number, the better a blanket keeps you warm.
The tog rating--the name was taken from the common slang for clothes--describes the warmth or 'Thermal Resistance' of a fabric, and is widely used in the UK to describe warmth levels of duvets and sleeping bags. For example, an adult winter duvet is usually between 10 and 15 togs and a summer duvet around 4.5 TOGs. It is recommended that quilts for babies and young children above 1 year should be no more than 4 togs, and the health professionals recommend that baby sleeping bags should be of a low tog rating. Tog values need to conform to British Standard BS4745:1990 which is the method for determination of thermal resistance of textiles.
The tog value of duvets is measured on a togmeter. This measurement is carefully controlled and described in a British Standard (BS5335:1991).