What is a TOG Rating and How to Use It in Spring and Summer?

You have probably spotted the number on a sleep sack label: 0.5 TOG. Maybe you googled it at 2 a.m. and closed the tab more confused than when you started. You are not alone.

Here is the simple version: TOG is a warmth rating. It tells you how much heat a garment retains. In spring and summer, it matters more than ever, because warmer rooms mean your baby needs less insulation and overheating is a recognized SIDS risk factor. Here is everything you need to know.

• TOG is a warmth number: Lower means cooler. Higher means warmer. It measures thermal resistance, not thickness.
• Go lighter in spring and summer: Warmer rooms mean your baby needs less insulation from their sleep sack.
• Do not trust hand-feel: A thick-feeling sack is not always a high-TOG sack. Check the label number.
• Layer underneath for flexibility: A lower TOG sack paired with the right base layer gives you control across warm and mild nights.
• The neck check is the final word: TOG is the plan. Two fingers on the back of the neck confirm whether it is working.
• The sheet matters too: A dense or synthetic sheet traps heat from below and undermines even a well-chosen sleep sack.

What does TOG stand for?

TOG stands for Thermal Overall Grade. It was developed in 1946 at the Shirley Institute in Manchester as a straightforward way to measure how much warmth a fabric retains, so parents and shoppers would not have to decode lab formulas. Standardized under British Standard BS 4745, it means a 0.5 TOG sack from one brand gives you the same warmth as a 0.5 TOG sack from any other. 

Why TOG Ratings Matter for Babies?

Here is the thing about babies: they cannot regulate their own body temperature the way you can. You get too warm in bed, you kick off the covers. Your baby just... lies there. Their thermoregulatory systems are still developing, which means the room they sleep in and the layers they wear are doing all the work.

The Key Asymmetry

And here is the part that makes this genuinely important. The AAP's 2022 safe sleep guidelines highlight a tricky asymmetry:

• A baby who is too cold will usually signal discomfort through crying or restlessness.
•  A baby who is overheating may not signal it the same way. They can sleep more deeply rather than waking to tell you something is wrong.

That second point is the important one. A settled baby is not always a safe one. The IDFL recommends baby sleeping bags carry a low TOG and that quilts never exceed 4 TOG, because the risk grows as the number rises.

The TOG Scale, Simply Explained

How to Read the Scale

• Lower TOG (0.2 to 1.0): Less heat retained. For warmer rooms and summer use.
•  Mid-range TOG (1.0 to 2.5): Moderate insulation. For temperate rooms in spring and autumn.
• Higher TOG (2.5 to 3.5): More heat retained. For cooler to cold rooms in autumn and winter.

One thing worth knowing: the AAP does not publish specific TOG-to-temperature tables. The pairings you see on sleep sack packaging come from manufacturers, which is helpful, but it is not the same as medical guidance. What the AAP confirms is the direction: lighter layers in warmer rooms, heavier in cooler. The neck check is always your final confirmation.

What Most Parents Get Wrong About TOG

Assuming that a thicker-feeling sack means a higher TOG can sometimes be a mistake. As the IDFL explains, the rating depends on fiber type, weave structure, and how effectively the material traps air. Two sacks can feel identical in your hands and behave completely differently in a warm room.

Why Hand-Feel Misleads You

• A loosely knit cotton sack may feel lightweight but allows air to flow freely, resulting in a lower TOG.
• A densely woven synthetic sack may feel similarly light but traps far more heat, giving a higher TOG.
• A fleece sack may feel plush and heavy, but depending on its construction, it can vent heat efficiently and land at a moderate TOG. 

TOG vs. Hand-Feel: What the Label Actually Tells You

The simple rule: ignore the feel, check the label. That number is the only thing telling you the truth.

Why Spring and Summer Specifically Trip Parents Up

Variable Room Temperatures

A nursery sitting at 70 degrees Fahrenheit in March can quietly climb to 78 by June. Nothing in your baby's routine changed, but the sleep sack that felt right in spring is now working against you.

Adults Feel the Room Differently

Easy to overlook: you and your baby experience that warm room completely differently. You are upright and moving, shedding heat all day. Your baby is lying still in a crib wearing a full-coverage sleep sack. 

To put it simply: one more layer than you would wear comfortably in the same room. In a 76-degree room in June, if you are in a light t-shirt, your baby likely needs just a lightweight onesie or diaper under the lightest available sleep sack. That is it.

The Case for a Lighter TOG Sleep Sack in Summer

A lower TOG sack earns its keep here. Instead of locking you into a fixed warmth level, it gives you control through layering underneath. Diaper only on a hot night, a light onesie on a cooler one, a short-sleeve bodysuit on a mild spring evening. One sack, the whole warm-weather range.

TOG Applies to More Than Just Sleep Sacks

Most people stop at the sleep sack. But here is something worth knowing: the sheet your baby lies on for 8 to 12 hours a night is part of the same thermal equation.

How the Sheet Fits Into the Equation

A dense or synthetic sheet traps heat from below regardless of what is on top. Pick a 0.5 TOG sack for summer breathability and lay it on a polyester sheet, and you have quietly undermined your own plan. Breathability needs to work at every layer.

The Neck Check: Your Real-Time Override

Numbers and guides can only take you so far. Once your baby is asleep, reach in and feel. Two fingers on the back of the neck, or your hand lightly on the chest.

What to Feel For

• Too hot: Skin feels sweaty or hot to the touch, baby may appear flushed. Remove one layer immediately.
• Too cold: Neck and chest feel cool or clammy; the baby may be restless. Add a layer.
• Just right: Skin feels warm and dry, baby is settled and comfortable.

Cool hands and feet are normal, by the way. That is just infant circulation. Always check the neck and chest to feel the right temperature. TOG is the plan; the neck check is the report card.

Seasonal Guide: Spring and Summer

Use this as a quick starting point. Your neck check and your sleep sack manufacturer's guidance are always the final word.

The AAP recommends 68 to 72 F as the ideal sleep environment. If your home does not get there, that is okay. Just adjust layers accordingly, and let the neck check tell you whether it is working.

Your TOG Cheat Sheet for Spring and Summer

TOG is just a number that tells you how warm a garment runs. In spring and summer, go lighter as rooms warm up, layer thoughtfully underneath, and finish with the neck check. Trust the number to get you in the right ballpark. Trust your hand to confirm you landed there.

And while you are sorting the sleep sack side of things, do not forget the sheet underneath. Joey & Joan's fitted sheets are made from 100% Jersey Cotton, OEKO-TEX certified, free of allergens and flame retardants. Jersey is a knit fabric with a naturally open structure that moves heat away from your baby's back rather than trapping it, sized to fit specific bassinets, cribs, and playards so it always lies flat and does its job. Browse the full range here.

Frequently Asked Questions

1. Can I use a baby blanket instead of a sleeping bag?

Yes, you can. As per the NHS, in this case, lie your baby on their back with their feet nearest the foot of the cot or Moses basket. This prevents any loose bedding from covering their face when they wriggle around.

2. Do TOG ratings differ between brands?

The temperature-to-TOG recommendations on packaging are set by each manufacturer. Follow your brand's guidance alongside advice from your pediatrician.

3. What TOG is appropriate for a newborn in summer?

In a warm room above 75 degrees Fahrenheit, a 0.2 to 0.5 TOG sack with just a diaper underneath is typically appropriate. Always confirm with the neck check.

4. Should I adjust TOG if my baby is unwell or has a fever?

Yes. A fever raises core temperature, so go lighter on TOG and check the neck more frequently. Overheating is an SIDS risk factor, and illness adds to that load.

5. Does humidity affect how warm a TOG rating feels in practice?

Yes. High humidity slows the body's ability to cool itself. In humid conditions, lean toward the lighter end of your TOG range.

Sources

• https://www.nhs.uk/baby/caring-for-a-newborn/sudden-infant-death-syndrome-sids/
• AAP Healthy Children: A Parent's Guide to Safe Sleep
• International Down and Feather Laboratory (IDFL): TOG Ratings Explanation
• Wikipedia: Tog (unit) and the Shirley Institute
• OEKO-TEX Standard 100: Official certification standards