TOG Ratings for Baby Sleep: A Full Guide by Temperature

TOG measures how much insulation a baby sleep bag provides. The higher the TOG, the warmer the bag. That part is straightforward. What gets more complicated is deciding which TOG your baby needs, because room temperature, the clothing underneath the bag, the materials used to make it, and your individual baby all need to be considered.

The chart below gives you the general temperature-to-TOG combinations commonly used as a starting point. It is not an official safe-sleep chart, and there actually isn't one. The Lullaby Trust specifically declines to publish a fixed temperature, clothing, and TOG chart because thermal insulation varies between products and babies.

At Treehouse, we don’t make sleep bags—we make the organic cotton layers worn underneath. Since parents often ask us about them, this guide covers sleep bags, layering, and how to tell if your baby is comfortable.

Anastasia Vasilieva Sustainable Fashion Entrepreneur

October 2026

TOG Ratings for Baby Sleep: A Full Guide by Temperature

What Is a TOG Rating?

TOG is a measure of thermal insulation, it tells you how much warmth a product is designed to retain. A higher TOG provides more insulation, while a lower TOG provides less. The Lullaby Trust describes TOG simply as a measure of insulation or warmth and recommends a lower TOG in warmer rooms and potentially a higher one in cooler rooms.

When shopping for baby sleep bags, you will commonly come across 0.5 TOG for warm conditions, 1.0 TOG for moderately warm rooms, 2.5 TOG for cooler or standard room temperatures, and sometimes 3.5 TOG for particularly cold conditions.

The important distinction is that TOG describes the insulation provided by the product.

It does not independently tell you what your baby should wear to bed. A 2.5 TOG bag over a thin bodysuit is not the same combination as a 2.5 TOG bag over several thick layers.

TOG Chart by Room Temperature

The following chart is a general starting point, based on the temperature bands and combinations commonly used for baby sleep bags. Always check the instructions supplied by the manufacturer of your particular sleep bag, since fabrics, construction, fit, and insulation differ between products. The temperature bands below should not be interpreted as NHS, AAP, or Lullaby Trust TOG recommendations.

Room temperature	Sleep bag TOG	General starting point for the layer underneath
75–81°F / 24–27°C	0.5 TOG	Short-sleeve bodysuit, or potentially just a diaper in a very warm room
68–75°F / 20–24°C	1.0 TOG	Short-sleeve bodysuit, moving to a long-sleeve layer at the cooler end
61–68°F / 16–20°C	2.5 TOG	Long-sleeve bodysuit or footed sleeper
BELOW 61°F / 16°C	2.5–3.5 TOG	Follow the specific sleep bag instructions and consider bringing the room toward the recommended 61–68°F / 16–20°C range rather than simply adding more and more insulation

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Think of this table as the place to begin, not the final word on what your baby should wear. Your sleep bag's instructions and your baby's actual temperature should override a generic chart.

There Is No Official TOG Chart, and That's Worth Knowing

Search for a baby TOG chart and you will find a huge number of organized grids telling you exactly what your baby should wear at 64°F versus 68°F. There is just one problem. National safe-sleep authorities do not provide a universal chart like this.

The Lullaby Trust explains why. Different products contain different materials in different proportions, those materials provide different levels of thermal insulation, and layering products together changes the total insulation again. Then there is the minor complication that babies are human beings rather than thermostatically controlled appliances. Every baby is different.

That makes TOG charts starting points rather than instructions.

Use a chart to narrow down the appropriate type of sleep bag for your room.
Then read the guidance supplied with the actual sleep bag you own.
Finally, check your baby rather than assuming that because three boxes on a chart lined up nicely, everyone is comfortable.

It is a slightly less satisfying answer than "68°F + 2.5 TOG + long sleeves = perfect," but it is a much more useful one.

What to Wear Under a Sleep Bag

The sleep bag gets most of the attention, but what goes underneath it is equally important.

As the room gets warmer, you can generally reduce the clothing underneath and use a lighter sleep bag. When the room is cooler, the combination may involve a more insulating sleep bag and a long-sleeve layer or sleeper underneath it. The instructions for your particular sleep bag should tell you which combinations its manufacturer recommends.

Warm temperatures

In a warm room, a lightweight short-sleeve organic cotton bodysuit can work under a lightweight sleep bag. In very hot weather, The Lullaby Trust notes that a short-sleeve vest or just a diaper may be enough.

Cooler temperatures

At cooler temperatures, a long-sleeve organic cotton bodysuit or organic cotton footed sleeper provides more coverage beneath the appropriate bag.

The American Academy of Pediatrics gives parents a broader rule:

Babies generally should be dressed in no more than one additional layer compared with what an adult would wear in the same environment. It also warns against overheating, which is associated with increased SIDS risk.

This is one reason adding "just one more layer to be safe" is not necessarily the safer choice.

Get the Room Temperature Right First

Before choosing whether you need 1.0 or 2.5 TOG, check the thermometer.

The NHS and The Lullaby Trust recommend a room temperature of approximately 61–68°F, or 16–20°C, for a sleeping baby. Both also warn that overheating is associated with increased SIDS risk.

That means TOG should not become a way of compensating indefinitely for an unusually cold room. If the room is below the recommended range and you can safely bring it closer to 61–68°F, that is preferable to simply continuing to pile on clothing and insulation.

Baby resting beneath lightweight bedding

A room thermometer is useful here because human temperature estimation is not very sophisticated. A room that feels "a little chilly" to one parent may feel perfectly comfortable to another. The Lullaby Trust recommends using a room thermometer rather than guessing.

If maintaining the recommended range is difficult, particularly during very hot weather, adjust clothing and bedding accordingly and continue checking your baby's temperature. The Lullaby Trust acknowledges that keeping a room between 61 and 68°F can be difficult in summer and recommends lighter clothing and bedding when necessary.

For a deeper explanation of temperature rather than TOG specifically, read our guide to the ideal temperature for a baby's room

The Real Check Is Your Baby

This is probably the most useful thing to remember from the entire guide.

Feel your baby's chest or the back of the neck.

The NHS recommends checking these areas to judge whether your baby is too warm. Cool hands and feet are normal and are not a reliable reason to add another layer. If your baby's skin feels hot or your baby is sweating, remove one or more layers.

That check matters because a chart cannot account for every sleep bag, every bodysuit, every room, and every baby.

Parent checking a baby's chest temperature

A room thermometer might say 67°F. Your chart might say 2.5 TOG. You might have selected exactly the base layer shown in the diagram. If your baby's chest nevertheless feels hot and sweaty, the correct response is not to admire your adherence to the chart. Adjust the layers.

The same principle applies when you are worried your baby may be too cold. Check the chest or back of the neck rather than using cold fingers or toes as your guide. The NHS specifically notes that cool hands and feet are normal.

We have a separate guide to the signs a baby is too hot while sleeping if you want to understand what to watch for in more detail.

Why Use a Sleep Bag Instead of Loose Blankets?

A well-fitting baby sleep bag is one way to keep a baby warm without adding loose bedding to the sleep space.

The NHS says baby sleeping bags can help reduce the risk of SIDS because they prevent babies from wriggling underneath bedding, provided the bag fits correctly around the shoulders so the baby's head cannot slip inside. It also says that when using a sleep bag, clothing can be adjusted according to the room temperature and TOG and no other bedding should be added.

The American Academy of Pediatrics likewise advises keeping loose bedding out of a baby's sleep area and says wearable blankets or sleep sacks can be used for warmth.

If you are wondering when loose bedding becomes appropriate, we cover that separately in our guide to when a baby can sleep with a blanket

Where Treehouse Fits In

We don't make sleep bags.

What we do make are the layers that sit directly against your baby's skin for hours at a time: short-sleeve bodysuits, long-sleeve bodysuits, and footed baby sleepers made from GOTS-certified organic cotton.

Choosing a sleep bag is only half of the bedtime clothing equation. You still need to decide what goes underneath it.

We favor breathable organic cotton base layers because they are simple, comfortable, and easy to adjust as the temperature changes. On warmer nights, that may mean a short-sleeve bodysuit. At cooler temperatures, it may mean long sleeves or a footed sleeper, always considered alongside the TOG and manufacturer's guidance for the sleep bag itself.

Shop organic cotton long-sleeve bodysuits

Shop organic cotton short-sleeve bodysuits

The Bottom Line

A TOG rating tells you how much insulation a sleep bag provides. Higher means warmer, lower means lighter.

The chart is useful for choosing a general starting point, but it should never outrank the instructions supplied with your particular sleep bag. The Lullaby Trust deliberately avoids prescribing one universal TOG-and-clothing chart because materials, layers, and babies differ.

Aim to keep the room around 61–68°F or 16–20°C, choose an appropriate sleep bag, adjust the clothing underneath it, and then do the part no chart can do for you: check your baby. Feel the chest or back of the neck rather than the hands and feet. If your baby feels hot or sweaty, remove a layer.

Treehouse makes soft, breathable organic cotton base layers designed to sit comfortably underneath whichever appropriate sleep bag you choose.

Frequently Asked Questions

What TOG should my baby wear?

Start with your baby's room temperature and the instructions for your particular sleep bag. As a general reference, lighter 0.5 to 1.0 TOG bags are commonly used in warmer rooms, while 2.5 TOG bags are commonly used at cooler standard room temperatures. The NHS identifies 2.5 TOG as suitable for standard room temperatures of 61–68°F or 16–20°C, but you should still adjust your baby's clothing and follow the instructions for the specific product.

What do you put under a 2.5 TOG sleep bag?

In a room around 61–68°F or 16–20°C, a long-sleeve bodysuit or footed sleeper under a 2.5 TOG sleep bag is a common starting combination. However, follow the instructions for your particular bag and check your baby's chest or back of the neck to make sure they are comfortably warm rather than hot or sweaty.

Is there an official TOG chart for babies?

No universal national chart tells parents that a particular room temperature always requires one exact TOG and clothing combination. The Lullaby Trust specifically says it cannot provide such a chart because different products have different materials and thermal insulation, layering changes insulation, and babies themselves differ.

What TOG should I use in summer or winter?

Think about the room temperature rather than the season printed on the calendar. A heated bedroom in January can be warmer than an air-conditioned bedroom in July. Lower TOG bags are generally used in warmer rooms and higher TOG bags in cooler ones. The Lullaby Trust recommends choosing TOG according to the temperature and following the sleep bag manufacturer's guidance.

Can my baby overheat in a sleep bag?

Yes. A baby can become too warm because of excessive clothing or bedding or because the room itself is too hot. Overheating is associated with increased SIDS risk. Check your baby's chest or the back of the neck and remove one or more layers if the skin feels hot or your baby is sweating.