Baby Sleeping Bag TOG Ratings: A Season-by-Season Guide

Quick answer

Match the TOG to your baby's room temperature, not the calendar. A 1.0 TOG bag suits warm rooms around 21–23°C, a 2.5 TOG is the everyday choice for roughly 16–20°C, and a 3.5 TOG is for cold rooms below about 16°C. If your nursery swings between seasons, buy one 2.5 TOG bag plus a lighter 1.0 TOG option rather than guessing at a single 'all-season' number.

What a TOG rating actually measures

TOG stands for thermal overall grade, a standard measure of how much heat a fabric traps. It is not a safety rating and it is not a temperature setting; it is a warmth score. A higher TOG means the bag holds more heat, so the same bag that keeps a baby comfortable in a cool room can cause overheating in a warm one.

This is why the room thermometer matters more than the season label on the packaging. Two October nights can differ by several degrees, and centrally heated flats often run warmer than the weather outside suggests. Check the nursery temperature at cot level, then pick the TOG that matches that number.

A simple TOG rating chart by room temperature

Use this as a starting point, then adjust for your baby. Every baby runs slightly differently, and the right check is the back of the neck: warm and dry is comfortable, hot or sweaty means too much, cool means too little.

Under the bag, keep the base layer simple. A short-sleeved bodysuit under a 1.0 TOG bag in summer, and a long-sleeved sleepsuit under a 2.5 or 3.5 TOG bag in winter, is usually enough. Adding blankets on top of a sleeping bag defeats the purpose and adds loose bedding.

• 3.5 TOG: cold rooms below about 16°C, often unheated bedrooms in deep winter
• 2.5 TOG: the everyday middle ground for roughly 16–20°C
• 1.0 TOG: warm rooms around 21–23°C, typical of heated nurseries and mild months
• 0.5 TOG: hot rooms above about 24°C, where airflow matters as much as fabric

What TOG for a winter baby

For most winter nurseries, a 2.5 TOG bag is the workhorse. It covers the widest range of heated-home temperatures, and you can layer a sleepsuit underneath on the coldest nights. A 3.5 TOG bag is the better pick only if the room regularly drops below about 16°C, for example in an older house or a room you deliberately keep cool.

The trade-off is flexibility. A 3.5 TOG bag is excellent for a cold snap but can be too warm once the heating is on, and it leaves you with less room to layer. If you are unsure, start with 2.5 TOG and add a warmer sleepsuit rather than buying the heaviest bag available.

Summer baby sleeping bag TOG choices

In summer, the goal flips from trapping heat to letting it escape. A 1.0 TOG bag suits air-conditioned or fan-cooled rooms, while a 0.5 TOG bag is the usual choice for hot rooms above about 24°C. Lightweight cotton or bamboo bags feel cooler against the skin and dry faster after night feeds.

Do not compensate for a hot room by leaving a baby in just a nappy and a heavy bag. Reduce the TOG first, then reduce the base layer. If the room is genuinely hot, a fan for air movement and a lighter bag will do more than any fabric change.

Fit guidance: the detail that makes or breaks a sleeping bag

A sleeping bag only works as intended when it fits. The neck opening should sit close enough that your baby cannot slip down inside the bag, but loose enough that there is no pressure or rubbing. As a rule, you should be able to fit two fingers between the neck and your baby's neck.

The armholes should let arms move freely, and the bag should end well below the feet so your baby can kick without the fabric riding up over the face. Weight and height ranges matter more than age, because a bag that is too long for a small baby creates the same slip risk as a too-large neck opening. Check the manufacturer's size chart and move up a size when the shoulders start to feel tight.

Safety points that outrank any TOG number

The safest baby sleeping bag is the one that fits well, is worn on its own without loose blankets, and keeps your baby at a comfortable temperature. Always place your baby on their back to sleep, and keep the cot clear of pillows, bumpers and toys.

Check the bag's fastenings before each use. A two-way zip or poppers that stay closed make night changes quicker and reduce the chance of the bag coming loose. If a bag has a loose thread, a broken zip pull or a stretched neck, retire it rather than repairing it with a safety pin.

Decision rules for picking a TOG

• If the room is below 16°C: Choose a 3.5 TOG bag and a long-sleeved sleepsuit underneath; check the room again after a few nights, since heating and insulation can shift the temperature. Cold-room pick: 3.5 TOG, layer up.
• If the room is roughly 16–20°C: Choose 2.5 TOG. This is the range most heated nurseries sit in, and it is the easiest bag to use year-round with a base-layer change. Default pick: 2.5 TOG.
• If the room is roughly 21–23°C: Choose 1.0 TOG and drop to a short-sleeved bodysuit if your baby feels warm at the back of the neck. Mild-room pick: 1.0 TOG.
• If the room is above about 24°C: Choose 0.5 TOG, keep the base layer minimal, and use a fan for air movement rather than adding more fabric. Hot-room pick: 0.5 TOG.
• If you are buying before the season starts: Buy the 2.5 TOG first and add a lighter or heavier bag later; a single heavy bag is the most common wasted purchase. Start with the middle, then specialise.

BABYGO® options that cover the TOG range

• BABYGO® Baby Sleeping Bag: Available in 3 sizes, 5 different togs, a range of colours and prints, with poppers for easy access and a QikZip two-way zipper. One product line covers the full season-by-season TOG range, so you can buy the same familiar fit in a lighter or heavier version as the nursery temperature changes.
• BABYGO® Sleepsuit & Sleeping Bag: A Zip Up Sleepsuit and Baby Sleep Bag bundle with fold-over hands and feet, and the sleeping bag size and TOG chosen separately. Buying the base layer and bag together lets you match the sleepsuit to the TOG you pick, which simplifies layering on cold nights and keeps night-time changes to one zip.
• BABYGO® Zip Sleepsuit | 3 Pack: A three-pack of QikZip zip-up sleepsuits made from breathable bamboo fibres with thermo-regulating qualities. A breathable base layer under a 2.5 or 3.5 TOG bag helps avoid overheating when the heating is on, and three sleepsuits mean you are not washing the same one every day.

Who this TOG approach suits

Best for

• Parents whose nursery temperature changes with the seasons or the heating schedule
• Caregivers who want one familiar sleeping bag style in several warmth levels
• Families who prefer to adjust base layers rather than buy a new bag every few months

Not for

• Anyone looking for a single bag to use in every temperature without adjusting clothing
• Babies who have outgrown the neck or shoulder fit of a bag, who need the next size up instead