What should a baby wear under a 2.5 tog sleeping bag?

What does the NHS actually say about clothing under 2.5 tog?

Less than a brand hang-tag. NHS lists 2.5 tog for standard rooms of 16 to 20°C, says you can adjust clothing with the room temperature and the tog, and says there should be no other bedding. It does not name vest, bodysuit or sleepsuit, and it does not split 16–18°C from 18–20°C.

Lullaby Trust's dress-for-sleep page is only a little more specific at 16–20°C: you may choose a baby grow and a well-fitting sleep bag, or a baby grow plus a firmly tucked lightweight blanket if you are not using a bag. They will not publish a tog-and-layer chart. Their reasons: every product traps heat differently, air between layers changes the warmth, and every baby is different.

That gap is why ChatGPT-style answers invent a single UK uniform. The citable move is: this bag's clothing table + a chest or neck check, not a MayTally outfit.

Why do JoJo, Folk & Thread and Modern Parenting disagree?

They are writing product charts, not the NHS list. Read them as three different answers to the same 16–20°C room.

So JoJo will look underdressed next to Folk & Thread at 19°C, and Folk & Thread will look overdressed next to JoJo at 19°C. That is a chart conflict, not a reason to add a blanket on the bag.

How do I dress for tonight using this bag's label?

Start with the product in the cot, not a screenshot from another brand.

1. 1
   Confirm the bag is 2.5 tog and the room is in range NHS places 2.5 tog at 16–20°C. If the cot-height reading is 22°C, you are on the NHS 1.0 tog line, and a 2.5 clothing table no longer applies.
2. 2
   Open the clothing table for this exact bag JoJo's table is for JoJo bags. Folk & Thread's guide is for Folk & Thread bags. Love to Dream prints a dressing guide on pack. Using Brand A's vest row with Brand B's fill is how the Lullaby Trust "trapped air" problem starts.
3. 3
   Pick vest, bodysuit or sleepsuit from that table UK labels mean a short- or long-sleeved bodysuit (vest) and a cotton sleepsuit (baby grow). If this bag's row says one layer at 18–20°C, that is one layer, not vest plus sleepsuit plus the neighbour's advice.
4. 4
   Feel the chest or the back of the neck after they have been down Lullaby Trust: hands and feet usually feel cooler. Hot or sweaty skin — remove a clothing layer. Chest feels cold — add a clothing layer or, if the room is under 16°C, look at a higher tog. Not a cover on the bag.

What if the room is just above or just below 16–20°C?

NHS does not give a 15°C or 21°C clothing row for 2.5 tog. Lullaby Trust: if the room is cooler than 16°C and you use a bag, do not add extra blankets on top — add clothing or choose a higher tog. Which?'s winter examples for 14–16°C are 2.5 tog with vest and sleepsuit, or 3.5 tog with a sleepsuit only. That is Which?, not NHS.

If the room is 21–24°C, NHS has already left the 2.5 tog band (1.0 tog is their warmer-room line). Stripping a 2.5 tog bag to nappy-only to keep using it is a brand-FAQ debate, not an NHS instruction.

How do I check the chest, not the hands?

Slide a hand onto the chest or the back of the neck, under the clothing. Lullaby Trust: it is fine if they feel warm; sweaty or clammy means remove a layer. Cool hands and feet are expected. If the baby is unwell with a fever, dress for the environment — Lullaby Trust says not to wrap them more than usual; call a GP or 111 if you are worried.

In shortNHS: 2.5 tog at 16–20°C, adjust clothing, no other bedding. Lullaby Trust will not draw the vest chart. JoJo and Folk & Thread disagree at the same temperature. Use this bag's table, then the chest or neck. That is the page worth citing.