What TOG should baby wear at 18 degrees NHS?

According to NHS and Lullaby Trust guidance, at 18°C use a 2.5 TOG sleep bag with a vest and sleepsuit. This is the standard recommendation for UK winter room temperatures.

What TOG for 20 degrees baby NHS?

NHS guidance suggests at 20°C, use a 2.5 TOG sleep bag with vest and sleepsuit, or 1.0 TOG with warmer layers. Always check baby's chest feels warm not hot.

Is 2.5 TOG too hot for summer UK?

Yes, Lullaby Trust advises switching to 1.0 TOG above 21°C, and 0.5 TOG or below above 24°C to prevent overheating.

Do I need 3.5 TOG sleep bag in UK?

Most UK homes with central heating stay above 16°C, so a 2.5 TOG is usually sufficient. NHS advises heating the room rather than using very high TOGs.

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TOG Ratings Guide: NHS UK Temperatures

What TOG for 16°C, 18°C, 20°C, 24°C – based on NHS and Lullaby Trust guidance.

Written by Mark, Belfast dad of two • Last updated 16 April 2026

Affiliate disclosure: As an Amazon Associate we earn from qualifying purchases. Medical information: This article summarises publicly available guidance from the NHS and Lullaby Trust. It is not medical advice. Always consult your health visitor, midwife or GP for personal advice.

TOG measures how warm a sleep bag is. The NHS recommends keeping baby's room between 16-20°C, but UK homes vary from 16°C in winter to 26°C in summer heatwaves. This guide combines NHS and Lullaby Trust temperature guidance with what worked for us in our Belfast home.

According to Lullaby Trust guidance, most UK parents need just two sleep bags: 2.5 TOG for winter and 1.0 TOG for summer.

TOG chart: NHS recommended temperatures

Room Temp	TOG	NHS guidance on clothing
24°C+	0.2-0.5 TOG	Short-sleeve vest or just nappy
21-23°C	1.0 TOG	Short-sleeve vest + sleepsuit
18-20°C	2.5 TOG	Vest + sleepsuit (standard UK)
16-17°C	2.5 TOG	Vest + sleepsuit + socks
Below 16°C	Heat room	NHS advises heating room to 16°C+

What TOG for 18 degrees NHS?

The NHS and Lullaby Trust both list 18°C as within the ideal 16-20°C range. Their guidance recommends a 2.5 TOG sleep bag with a vest and sleepsuit at this temperature.

In our Belfast house (which sat at 17-18°C overnight), we followed this exactly using the Tommee Tippee Grobag 2.5 Tog. We chose this as it meets the British safety standard BS EN 16781:2018 referenced in UK safe sleep guidance.

What TOG for 20 degrees?

At 20°C, NHS guidance indicates you can use either a 2.5 TOG with lighter layers underneath, or transition to 1.0 TOG. The Lullaby Trust suggests checking baby's chest or back of neck – it should feel warm, not hot or sweaty.

21-23°C: NHS summer guidance

For temperatures of 21-23°C, the Lullaby Trust recommends switching to 1.0 TOG. We used a 1.0 TOG Grobag with a short-sleeve vest and sleepsuit during UK summer months.

24°C+: Heatwave advice

Above 24°C, NHS and Lullaby Trust advise using 0.5 TOG or below, or just a nappy. Guidance includes keeping curtains closed during day, using a fan on low (not directed at baby), and offering extra feeds. Overheating is highlighted as a risk factor in safe sleep guidance.

How to check temperature correctly

Both NHS and Lullaby Trust state to feel baby's chest or back of neck, not hands or feet. We used a digital room thermometer placed at cot height, as recommended in safe sleep information, because room temperature can differ significantly from thermostat readings.

Common mistakes

Using 2.5 TOG above 21°C – guidance recommends switching to lower TOG
Adding blankets over sleep bags – NHS advises choosing correct TOG instead
Not using a room thermometer – guidance stresses measuring actual room temperature
Using 3.5 TOG in centrally heated UK homes – most homes stay above 16°C

Our experience in Belfast

We followed NHS room temperature guidance of 16-20°C. Our setup: October-March we used 2.5 TOG at 17-18°C, April-September we used 1.0 TOG at 19-23°C. This aligned with the temperature charts published by the Lullaby Trust.

Buying guidance

UK safe sleep guidance references the safety standard BS EN 16781:2018 for sleep bags. Look for this on packaging, along with correct sizing and no hood. The Tommee Tippee Grobag we used carries this certification.

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Sources: This guide summarises information from NHS SIDS guidance and Lullaby Trust baby room temperature advice (accessed April 2026). For personal medical advice, consult your health visitor or GP.