Tog Rating Guide
4.5 tog Lightweight, suitable for the warmer, summer months
7.5 tog          Medium weight, suitable for the cooler, spring / autumn months
9/10.5 tog Medium/heavy, suitable for late autumn / early spring
12/13.5 tog Heavy weight, suitable for the cold, winter months
15 tog    Extra heavy weight, suitable for the harshest winter months

A 'tog rating' is the measurement of a duvets ability to trap and hold onto warm air (a measurement which is not necassarily determined by a duvets thickness alone). The higher the tog rating, the warmer the duvet:

Duvets with a higher tog rating (whichever fill material is being used) - will always require more of that material in order to increase the tog level (meaning that the price will be slightly higher in order to account for this). It would be safe to expect that a 4.5 tog rated duvet, would be quite thin & lightweight, whilst a 15 tog duvet would be reasonably heavy - with a generous filling.

Most people prefer to choose one duvet for use throughout the entire year to save money, wereas many - becoming too cold during the winter months & too hot during the summer months - opt to purchase duvets with a different tog rating dependant on the season.

Not many people know that there is a third option which may be very benificial......An all seasons duvet that offers the best of both worlds - keeping you at the perfect temperature for every season, whilst saving on money!

As a general rule, synthetic materials such as hollowfibre / polyester / microfibre will be a little heavier in terms of fill weight, compared to natural materials such as feather & down.

However, there are certainly many benefits to choosing a synthetic duvet - including lower production cost's (meaning a much lower purchase price!) and the fact that they are inherently non-allergenic.