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Baby sleeping bag TOG guide: what do the numbers mean?
TOG describes how much insulation a sleeping bag provides. A higher number means more warmth. It is useful when comparing bags, but it does not tell you the complete outfit your baby needs underneath.
What are 0.5, 1.0 and 2.5 TOG for?
The NHS lists 2.5 TOG for 16–20°C, 1.0 TOG for 20–24°C and 0.5 TOG for 24–27°C. Use these as general ranges, then follow the specific bag's temperature, sizing and clothing instructions. With a sleeping bag, the NHS advises against additional bedding.
Why two clothing charts might disagree
The Lullaby Trust does not give one universal TOG-and-clothing chart: materials, combinations of layers and babies differ. Two products with the same rating can therefore come with different clothing guidance.
Read the label before buying another bag
Find the brand, model, size and TOG on the bag you already own. Then look up its own guide. A photo of a retailer's generic chart may belong to another range, even when the colours and numbers look familiar.
If the label is missing or you cannot identify the product, do not guess its rating from how thick it feels. Ask the manufacturer. Keep the instructions somewhere easy to find for anyone else putting your baby to bed.
Choose for the room, not the season
A warm bedroom in winter does not call for a warmer bag just because it is January. Equally, a cool bedroom in summer may differ from the forecast outside. Read the temperature in the room your baby actually sleeps in.
If the temperature sits at the boundary between two ranges, check your product's guidance rather than treating the boundary as an exact switch. The calculator offers examples; it cannot assess the bag's fit or decide how your baby feels.
Sources & further reading
These organisations support the guidance linked above. They have not reviewed or endorsed Snugometer or its outfit examples.