Room Temperature Guide: Which TOG Rating Sleep Sack to Use at 68°F–78°F

The 68°F–78°F Problem

Most US nurseries in summer land somewhere between 68°F and 78°F — and that ten-degree window actually spans three different TOG ratings. That’s the part the packaging rarely explains. Parents who set the thermostat to 72°F and parents whose nursery creeps to 77°F by midnight are dealing with very different sleep environments, but they’re often reaching for the same sleep sack.

TOG stands for Thermal Overall Grade — a standardized measure of how much warmth a fabric retains. The higher the number, the more insulation the garment provides. A higher TOG rating indicates the sleepwear provides more thermal insulation, making it suitable for colder temperatures, while a lower TOG rating is appropriate for warmer temperatures. The ratings most parents encounter in sleep sacks run from 0.5 at the lightest end up to 2.5 or 3.5 for winter use.

The 68°F–78°F band is where the decision gets genuinely nuanced. A single TOG does not cover that entire range safely, and getting it wrong in either direction has real consequences. Overheating increases the risk of Sudden Infant Death Syndrome (SIDS), while too little warmth can cause discomfort and disturb sleep. So here is a temperature-by-temperature breakdown of exactly which TOG to reach for, and what to put underneath.

The Quick-Reference TOG Map: 68°F to 78°F

75°F–78°F (warm to hot nursery)

At this range — common in US homes where the AC is set for adult comfort rather than nursery safety, or in homes without central air — a 0.5 TOG sleep sack is the right call. When the weather is warm (75–80°F), use a sleep sack with a TOG rating of 0.5 to 1.0, paired with a short-sleeve cotton bodysuit. At the upper end of this band (76°F–78°F), most babies will be most comfortable in just a diaper under the 0.5 TOG. At 75°F, a short-sleeve onesie works well underneath.

The fabric matters here as much as the rating. A 0.5 TOG made from a breathable, moisture-wicking material will perform very differently from one made with a synthetic shell. Look for muslin or bamboo-derived fabrics that allow air to circulate rather than trap it.

72°F–75°F (the most common AC nursery range)

This is where most climate-controlled US nurseries land. For room temperatures between 72°F and 75°F, a 0.5–1.0 TOG paired with a short-sleeve bodysuit is the standard recommendation. In practice, 72°F–73°F tends to sit at the upper limit of 1.0 TOG comfort, while 74°F–75°F is more comfortably served by a 0.5 TOG — especially if the room holds that temperature through the night rather than dropping after midnight.

Parents often find that a 0.5 TOG with a short-sleeve onesie at 73°F gives them more flexibility: if the room cools slightly overnight, the onesie adds just enough coverage without the risk of overheating.

68°F–72°F (cooler, often AC-heavy rooms)

A 1.0 TOG sleep sack is usually the right choice for rooms between 68°F and 72°F, paired with a long-sleeve bodysuit or lightweight pajamas. This is also the range that pediatric sleep guidance tends to cite as the sweet spot for safe infant sleep. Research suggests cooler rooms within the recommended range generally promote deeper sleep and reduce the risk of overheating.

A lot of research recommends a safe ambient nursery temperature for babies between 68 and 72 degrees, and most 1.0 TOG sleep sacks recommend this range. At 68°F specifically, some brands recommend moving toward a 1.0–1.5 TOG with a long-sleeve base layer underneath. The key variable is whether the room stays at 68°F all night or whether it’s the low point of a temperature that fluctuates — if it fluctuates upward, lean toward 1.0 TOG and let the base layer do the adjusting.

Why the Nursery Temperature You Think You Have May Not Be the One You Actually Have

Thermostat readings and nursery temperatures often diverge — sometimes by 4°F to 6°F. A few factors that push nursery temperatures higher than expected:

• Sun exposure: Sunlight through a window can heat a room quickly in the afternoon. A west-facing nursery that gets afternoon sun can retain that heat well into the evening, even with AC running.
• Drafts and vents: Drafts from old windows can make a room feel colder than the thermostat indicates. Conversely, a vent blowing directly into the crib area creates localized cooling that the room thermometer won’t capture.
• The DOE thermostat recommendation: The U.S. Department of Energy recommends setting the air conditioner to 78°F during summer for energy efficiency. Many US families follow this guidance, which means the nursery — especially upper floors where heat rises — can sit several degrees above the thermostat setting.

The most accurate way to know your nursery’s actual temperature is a dedicated room thermometer placed near crib height, away from vents and windows. Check it right before putting baby down, and again in the morning — overnight temperatures can drop 3°F–5°F even in a climate-controlled home, which may shift your TOG choice.

What to Wear Underneath: Layer Logic for 68°F–78°F

TOG is only part of the equation. What your baby wears under the sleep sack changes the effective warmth significantly, and layering underneath is often more practical than switching sleep sacks mid-season.

Here is a simple framework:

• 75°F–78°F: Diaper only, or diaper + short-sleeve onesie → 0.5 TOG sleep sack
• 72°F–75°F: Short-sleeve onesie → 0.5 TOG, or diaper + short-sleeve onesie → 1.0 TOG if the room tends to cool overnight
• 68°F–72°F: Long-sleeve bodysuit or lightweight footie pajamas → 1.0 TOG

Parents can adjust the child’s clothing underneath depending on whether the child is running hot or cold. A baby who consistently runs warm — flushed cheeks, sweaty neck — should be dressed at the lighter end of whatever range applies. A baby who tends to run cool can wear a slightly warmer base layer within the same TOG.

The most reliable comfort check is not the hands or feet, which naturally run cooler than the core. Check your baby’s chest or neck — it should feel warm and dry, not sweaty. Sweaty means too warm; cool and clammy means too cold.

In general, a baby will need one additional layer compared to what an adult would wear to be comfortable in the same environment. That rule of thumb holds reasonably well across the 68°F–78°F range.

A Note on Fabric: TOG Rating Alone Does Not Tell the Full Story

Two sleep sacks with the same TOG number can feel very different against a baby’s skin depending on what they are made from. The TOG value of a sleep sack is not entirely based on how thick the fabric is, but the type of material it’s made of. A tightly woven synthetic at 0.5 TOG may trap more moisture than a loosely woven bamboo muslin at the same rating — and moisture retention is what leads to overheating in warm rooms.

For the 68°F–78°F summer range, breathable, moisture-managing fabrics tend to outperform heavier wovens even at equivalent TOG numbers. Muslin (particularly bamboo-derived muslin), TENCEL™ Lyocell, and similar materials move moisture away from the skin rather than holding it — which matters when a nursery sits at 76°F and the night is long.

Loulou Lollipop’s sleep bags are available in 0.5 TOG in Tanboocel™ muslin and 1.0 TOG in TENCEL™ Lyocell — both materials chosen specifically for their breathability and temperature-regulating properties. The 0.5 TOG Muslin Sleep Bag features a sleeveless design and soft, breathable muslin fabric, making it well-suited to the 72°F–78°F end of the summer range. The 1.0 TOG TENCEL™ Sleep Bag is insulated with light Dupont Sorona and works well for the 68°F–72°F range where a bit more coverage is appropriate without adding bulk. Both are manufactured at an OEKO-TEX Standard 100 certified factory, which means no toxic chemicals — relevant when a baby is spending 10–12 hours in direct contact with the fabric.

Browse the full sleep bag collection at Loulou Lollipop to find the right TOG for your nursery’s temperature.

The Condensed Answer (For Quick Reference)

If you want the short version to screenshot and keep in the nursery:

• 78°F: 0.5 TOG + diaper only
• 75°F–77°F: 0.5 TOG + short-sleeve onesie
• 72°F–74°F: 0.5 TOG + short-sleeve onesie, or 1.0 TOG + diaper/short-sleeve onesie
• 68°F–71°F: 1.0 TOG + long-sleeve bodysuit or lightweight footie pajamas

And the check that matters more than any chart: feel the back of baby’s neck at the first overnight waking. Warm and dry means you got it right. Adjust from there — the chart is a starting point, not a fixed rule. Individual babies run warmer or cooler, rooms fluctuate, and brands may vary slightly in their specific recommendations, so following the guidance that comes with your particular sleep sack is always worth doing alongside any general guide.