A medium sleep bag is a wearable blanket that zips on over your baby's sleep clothes, with the arms out. Its label says 1.0 TOG. TOG is the warmth number on a sleep bag: 0.5 is light, 1.0 is medium and 2.5 is warm. In the US it is called a sleep sack.
It is the one for rooms of 20–24°C (68–75°F). Put your baby down on the back, zipped in, with nothing else in the crib. If the room stays in that range all year, it can be the only sleep bag you need.
In a cooler room, use a warm sleep bag, and in a hotter one a light sleep bag. When you buy a medium bag, look for 1.0 TOG on the label, and skip any bag with a hood, so the head stays uncovered.
- For ages0–3years
- You'll need2–3per size
- For a room at20–24°C68–75°F
What to wear under it
A bodysuit underneath is enough. Choose its sleeves by the thermometer in the room.
At 22–23°C (72–73°F), a short-sleeve bodysuit. At 20–21°C (68–70°F), a long-sleeve bodysuit, so the arms are covered too. On a 24°C (75°F) night, just a diaper under the bag.
The guide to dressing a baby for sleep has an outfit for every room.
Types of medium sleep bag
Sleeveless
The usual kind, for any night in the range. The arms come out through two armholes, so their only cover is the bodysuit's sleeves.
With sleeves
Thin, fitted long sleeves cover the arms, so the bodysuit underneath can have short sleeves. They suit the cooler end of the range, near 20°C (68°F).
With legs
Two roomy legs instead of one wide bottom, for a baby who walks. Shops also call it a walker bag or a sleep sack with legs.
Sleep bag sizes
Sleep bags come in fewer sizes than clothes, and the later ones last longer: the first two about three months each, the next about a year. Some makers sell one 0–6 month size instead of the first two.
Sleep bag sizes by weight, height and age
Go by weight: shops name sizes by age or by letter, but the weights match.
0–3 mXS3–6 kg7–13 lbUp to 62 cm (24 in)Worn about 3 months- 3–6 mS6–8 kg13–18 lb62–68 cm (24–27 in)Worn about 3 months
- 6–18 mM8–11 kg18–25 lb68–86 cm (27–34 in)Worn about a year
- 18–36 mL11 kg and up25 lb and up86–98 cm (34–39 in)Worn about a year and a half
Most first sizes start at about 3 kg (7 lb). Until your baby gets there, use a swaddle or a sleepsuit. These are typical sizes, so check the chart for your bag.
When to move up a size
Move up only once your baby is inside the next size's range: a bag bought to grow into can let your baby slip down inside it. Zip your baby in and check three things: the length of the old bag, and the neck and armholes of the new one.
1. The length
Your baby needs room to bend the knees and kick. Once the feet press the bottom with the legs stretched out, or your baby reaches the top of the height range, the bag is outgrown.
- Good: Knees bend up freely
- Good: Room below the feet
- Not good: Feet press the bottom seam
2. The neck
Zipped up, the neckline sits below the chin, with room for one or two fingers. If it slides up over the mouth, the bag is too big for now.
- Good: Neckline stays below the chin
- Good: One or two fingers fit inside
- Not good: Neckline slides over the mouth
3. The armholes
They sit close around the shoulders without pinching, so the arms cannot slip back inside. Wide, gaping armholes also mean the bag is too big for now.
- Good: Edge sits close to the shoulder
- Good: No red marks after a night
- Not good: Gap where an arm slips inside
When your baby starts to walk
A sleep bag still works for a baby who pulls up to stand. Once your baby walks, a bag with legs is easier: your toddler can get out of a toddler bed or a floor bed and walk without tripping over a long bag.
With the feet out, bare toes grip the floor. On a cooler night, fold the foot covers over the toes. Covers with grippy soles help stop slips on a smooth floor.
Is 1.0 TOG right for your room?
It depends on the room, not the season. Check the temperature near the crib at bedtime.
Which TOG bag to choose for tonight
Your room tonight
22°C (72°F)
Move the thermometer to your room's temperature.
Short-sleeve bodysuit, 1.0 TOG Medium sleep bag
Short-sleeve bodysuit- 1.0 TOGMedium sleep bag
Makers' charts differ, so follow your bag's label.
Questions parents ask
What temperature is a 1.0 TOG sleep sack for?
Rooms of 20–24°C (68–75°F), measured near the crib at night. If your room drops below 20°C (68°F) in winter, you will need a 2.5 TOG bag for those months too. The TOG guide compares every rating.
Is a 1.0 TOG sleep sack okay for summer?
Yes, on nights when the bedroom stays at 24°C (75°F) or cooler. On hotter nights, change to a 0.5 TOG bag, and at 28°C (82°F) and above your baby sleeps in just a diaper, with no bag.
Do babies wear pajamas under a sleep sack?
Under a 1.0 TOG bag, usually not. In a room of 20–24°C (68–75°F), a bodysuit under the bag is all your baby needs. Footed pajamas (a sleepsuit, or footie) are for a cooler night at 18–19°C (64–66°F), if you have no warmer bag.
Will my baby's arms get cold in a sleeveless sleep sack?
Not if the bodysuit suits the room. Hands often feel cool even when your baby is warm, so feel the back of the neck instead: warm and dry means the outfit is right.
Should a 2 year old still sleep in a sleep sack?
Yes, if it still fits: sizes run to 36 months, and some to 4 years. After 12 months a light blanket is an option too, but a toddler who kicks off a blanket stays covered in a sleep bag. Most families stop at 2 or 3, when their child moves to a bed with a blanket.
Is a 1.0 TOG sleep sack safe?
Yes, when it fits and suits the room. A sleep bag keeps a baby warm without loose blankets in the crib. Skip weighted ones.
Can a baby overheat in a 1.0 TOG sleep sack?
Yes, if the room is warmer than 24°C (75°F) or there are too many clothes underneath. If the back of the neck feels hot or sweaty, take a layer off. Never put a second bag on top for warmth, because two 1.0 TOG bags do not make a 2.0.
