Understanding TOG Ratings for Baby Sleep Bags: A Parent's Guide

Quick answer

TOG (Thermal Overall Grade) measures how well a sleep bag traps warmth. A higher TOG means a warmer bag. Most babies sleep comfortably in a 1.0 TOG bag in a room around 20-22°C (68-72°F), a 2.5 TOG bag in a cooler room around 16-18°C (61-64°F), and a 0.5 TOG bag in warm rooms above 24°C (75°F). Always check your baby's chest or back to confirm comfort, not just the number.

If you have ever stood in a shop staring at sleep bag labels wondering what 1.0 TOG or 2.5 TOG actually means, you are not alone. TOG is simply a warmth score, and once you understand the scale, choosing a sleep bag becomes a practical decision rather than a guessing game.

This guide answers the questions parents ask most about TOG ratings, room temperature, and layering. It also explains why the fabric and fit of a sleep bag matter alongside the TOG number, and how to adjust what your baby wears underneath as the seasons change.

What does TOG actually measure?

TOG stands for Thermal Overall Grade. It is a laboratory measurement of how much heat a textile or garment traps. The scale runs from 0.5 TOG for very light fabrics up to 3.5 TOG for the warmest winter bags. A 1.0 TOG bag provides roughly twice the insulation of a 0.5 TOG bag, and a 2.5 TOG bag is warmer still.

The rating applies to the whole sleep bag, including any filling and the outer fabric. It does not tell you the exact temperature your baby will feel, because that depends on the room, what they wear underneath, and their own body. Think of TOG as a starting point for matching the bag to the season, not a guarantee.

• Check the label for a TOG number before buying; if a sleep bag does not state one, treat it as a light summer option unless the brand says otherwise.
• A higher TOG is not automatically better. Overheating is a risk, so match the bag to the room rather than to the season name.

How do I match TOG to my baby's room temperature?

The most common approach is to keep the nursery between 16°C and 20°C (61-68°F) for safe sleep and choose a TOG that suits that range. A 2.5 TOG bag is the usual choice for 16-18°C (61-64°F), while a 1.0 TOG bag works well around 20-22°C (68-72°F). For warmer rooms above 24°C (75°F), a 0.5 TOG bag or a light muslin cloth is often enough.

These are guidelines, not rules. Premature babies, babies who run hot, and rooms with fluctuating temperatures all need a little adjustment. The best test is to feel your baby's chest or the back of their neck about 20 minutes after they fall asleep. If it feels hot or sweaty, remove a layer. If it feels cool, add one.

• Keep a room thermometer near the cot so you can check the actual temperature instead of guessing.
• If the room sits between two TOG ranges, choose the lower TOG and add a layer underneath rather than choosing the warmer bag.

What should my baby wear under a TOG sleep bag?

The sleep bag is only one part of the outfit. Underneath, most babies wear a bodysuit or pyjamas. In a 2.5 TOG bag in a 16-18°C room, a long-sleeved bodysuit and pyjamas are typical. In a 1.0 TOG bag at 20-22°C, a short or long-sleeved bodysuit alone often works. In a 0.5 TOG bag in a warm room, a nappy and a thin bodysuit may be all your baby needs.

Layering is easier to adjust than changing the bag. If you are unsure, start with fewer layers and add a thin one if your baby feels cool. Remove layers one at a time if they feel warm. Avoid blankets in the cot, because a sleep bag is designed to stay in place while blankets can be kicked off or cover the face.

• Choose sleep bags with a fitted neck and armholes so the bag does not ride up over the face.
• If your baby is unwell or has a fever, use a lower TOG and fewer layers, and follow your health professional's advice.

Does fabric type change how a TOG rating feels?

Two bags with the same TOG can feel different depending on the fabric. Organic cotton and muslin are breathable and help move moisture away from the skin, which can make a 1.0 TOG bag feel comfortable in slightly warmer conditions. Quilted or coated fabrics trap more warmth and may feel heavier even at the same rating.

For example, the Changing Bag w/pram straps - OCS - Berries has a water-repellent coating on both the outside and inside, which is useful for a pram bag but not something you would want in a sleep bag. For sleep, look for breathable natural fibres and a TOG that matches the room. The Muslin Cloth, 2-pack - GOTS - Blush is a good example of a light, breathable layer for warm nights or for tucking around a baby during feeding.

• Cotton and muslin breathe well; synthetic fillings can feel warmer at the same TOG.
• Always follow the care label, because washing can affect a fabric's loft and insulation over time.

How many TOG sleep bags do I actually need?

Most families manage well with two bags: a 1.0 TOG for spring and autumn and a 2.5 TOG for winter, plus a 0.5 TOG for heatwaves if your summers are hot. If your nursery stays within a narrow temperature range all year, one well-chosen bag may be enough. Buying two in different TOGs gives you flexibility without overfilling the cupboard.

If you are building a changing station at the same time, a Diaper Caddy - OCS - Blueberries keeps nappies and wipes together and is easy to move between rooms. It does not affect sleep temperature, but it does make night changes quicker and calmer, which helps everyone get back to sleep.

• Wash your sleep bag before first use and check the TOG label again after a few washes.
• A sleep bag that is too large can slip over the face, so choose a size that fits your baby's weight and height.

TOG questions parents ask most

What TOG should a newborn sleep in?

Newborns cannot regulate their temperature well, so a 2.5 TOG bag in a 16-18°C room or a 1.0 TOG bag at 20-22°C is a common starting point. Check the chest or back of the neck to confirm comfort. Start with the room temperature, not the season.

Can I use a 2.5 TOG bag in summer?

Only if the room is genuinely cool, around 16-18°C. In a warm summer room, a 2.5 TOG bag can cause overheating. Switch to a 0.5 or 1.0 TOG bag and fewer layers underneath. If in doubt, go lighter and add a layer underneath.

Does a higher TOG mean a better sleep bag?

No. A higher TOG simply means more warmth. The right TOG is the one that matches your baby's room and clothing. A 1.0 TOG bag can be the better choice for most of the year in a typical nursery. Match the number to the room, not to the price or thickness.

How do I check if my baby is too warm?

Feel the chest or the back of the neck. It should feel warm but not hot or sweaty. Hands and feet often feel cooler than the core, so do not use them as your main guide. Chest and neck are the reliable check points.

Products that support a calm sleep routine

• Muslin Cloth, 2-pack - GOTS - Blush: Soft muslin cloth in 100% premium organic, GOTS-certified cotton with lovely Cam Cam prints. The muslin cloths have many functions. Perfect for the changing table, the pram or to cuddle with. After wash, the muslin will get a slightly textured look. A breathable muslin cloth is useful for warm nights when a full sleep bag would be too warm, and it doubles as a light cover during feeds.
• Diaper Caddy - OCS - Blueberries: Practical Diaper Caddy for diapers and other essentials for the changing situation. Perfect to create order on the changing table and super easy to move around the house and bring along when going out or to the summer house. Keeping changing supplies organised means fewer lights-on moments during night changes, which helps your baby settle back to sleep.
• Wash Cloth, 4 pack - GOTS - Bicycles: This four-pack of soft muslin wash cloths from Cam Cam Copenhagen features two by two of the brand's beautiful prints, including the Bicycles design. A practical, gentle-feeling addition to everyday washing and care routines. Soft muslin wash cloths are gentle for wiping a sweaty neck or face after a warm night, without disturbing your baby's sleep.

TOG ratings are a practical tool, not a complicated science. Pick a bag that matches your nursery temperature, dress your baby in breathable layers underneath, and check their chest or neck to confirm comfort. With one or two well-chosen TOG bags and a few soft muslin essentials, you can adjust quickly as the seasons change and help everyone sleep a little better.