How to Choose the Right Size Baby Sleep Sack When Ordering Online in Canada

Why Sizing a Sleep Sack Online Feels Harder Than It Should

Ordering a baby sleep sack online in Canada is straightforward — until you’re staring at a size chart that lists both weight and height ranges, a TOG number you’ve never heard of, and three different fabric options, all while your newborn is due in six weeks.

The good news: once you understand the two decisions you’re actually making — physical size and TOG warmth rating — the rest falls into place quickly. This guide walks through both, with specific numbers for Canadian nurseries and a reference framework based on Loulou Lollipop’s sleep sack size chart, which covers newborns through toddlers.

Step 1: Get the Physical Size Right

Sleep sack sizing is based on weight and height together, not age alone. Age labels on baby products are notoriously unreliable — a three-month-old can weigh anywhere from 11 to 17 lbs depending on the baby. Using age as your only guide is how you end up with a sack that either swamps a small newborn or pinches a fast-growing four-month-old.

The Loulou Lollipop sleep bag size chart breaks down as follows:

Two fit rules matter most. First, the neck opening: a sleep sack should fit snugly enough that your baby’s head cannot pass back through the opening — this is a safety standard, not a comfort preference. Second, the body length: there should be room for the legs to move and kick, but not so much extra fabric that the sack bunches up around the face when baby wriggles.

If your baby is between sizes on weight but at the upper end of height, size up. If they’re between sizes on height but lighter, stay in the smaller size and check the neck fit. When in doubt, most brands — including Loulou Lollipop — have a customer service team you can contact before ordering.

One practical tip: measure your baby’s length the day before you order, not at their last pediatrician visit. Babies grow fast enough that a two-month-old measurement can already be off.

Step 2: Choose the Right TOG for Your Canadian Nursery

TOG stands for Thermal Overall Grade — it’s a standardized measurement of how much warmth a fabric provides. The higher the number, the warmer the garment. Ratings for baby sleep sacks typically range from 0.5 to 3.5, and the number is consistent across brands: a 1.0 TOG from one manufacturer provides roughly the same insulation as a 1.0 TOG from another.

This matters a lot in Canada, where nursery temperatures can swing by 8–10°C between a July night in Vancouver and a February night in Edmonton. The general framework:

The widely cited target for a Canadian nursery is 20–22°C (68–72°F). That’s the range most paediatric guidelines point to, and it’s also the range where a 1.0 TOG sleep sack paired with a light base layer tends to work well year-round — with a swap to 0.5 TOG in summer and 2.5 TOG in a cold Canadian winter.

A few things worth knowing about TOG and fabric:

• Thickness is not the same as warmth. The type of material matters more than how heavy the fabric feels. TENCEL™ Lyocell, for example, is lightweight but actively manages body heat and moisture — which is why it’s used in Loulou Lollipop’s 1.0 and 2.5 TOG sleep bags rather than a thicker cotton fill.
• Overheating is the bigger risk. Babies cannot regulate their body temperature the way adults can, and overheating is a known risk factor for SIDS. When choosing between two TOG options, the general guidance is to go with the lower one and adjust the base layer underneath.
• Cold hands ≠ cold baby. Babies’ extremities are often cool even when their core temperature is fine. To check if your baby is too warm or too cold, feel the back of the neck or the chest. Warm and dry is correct. Hot or clammy means reduce a layer.

Loulou Lollipop’s sleep bag collection offers 0.5 TOG in breathable Tanboocel muslin, and 1.0 and 2.5 TOG in TENCEL™ Lyocell — a material made from sustainably sourced eucalyptus tree pulp using a closed-loop process that recycles 99.5% of the solvents used in manufacturing. For Canadian parents who want a material that performs well across the country’s wide seasonal range, TENCEL’s temperature-regulating properties make it a practical choice beyond just the sustainability credentials.

The Canadian Seasonal Reality: You Probably Need Two TOGs

Most Canadian families end up needing at least two sleep sacks in rotation — not because brands want to sell more product, but because the gap between a July nursery and a January nursery is simply too wide for one TOG to cover safely.

A workable setup for most of Canada:

• 0.5 TOG muslin for late spring through early fall, when nurseries tend to run 22°C and above
• 2.5 TOG TENCEL for late fall through winter, when even a well-heated home can drop below 20°C overnight
• A 1.0 TOG works as a year-round option in homes with consistent climate control, or as a transitional piece for shoulder seasons

Having two in rotation also solves the laundry problem. Sleep sacks get used every night and occasionally need a middle-of-the-night wash. With one in use and one clean, you’re not scrambling.

Forced-air heating in Canadian homes is worth a specific note: heating vents can make one room significantly warmer than the rest of the house, especially if a vent is directly in the nursery. A standalone digital thermometer at crib level — not mounted high on a wall where warm air pools — gives you a more accurate read than the hallway thermostat.

What to Check Before You Click ‘Add to Cart’

Before finalising an online order, run through this quick checklist:

Weight and height both fit the size range. If they conflict, prioritise height for body fit and confirm the neck opening is snug enough.

TOG matches your current nursery temperature. Not your ideal temperature — your actual nursery temperature at 2 a.m., which may be different from what you think.

The fabric is OEKO-TEX certified. This certification means the fabric has been tested for harmful substances. It’s a non-negotiable for anything going against a baby’s skin all night. Loulou Lollipop sleep bags are manufactured at an OEKO-TEX Standard 100 certified factory.

The zipper design works for night changes. A two-way zipper that opens from the bottom means you can do a diaper change without fully removing the sleep sack — a small detail that matters a lot at 3 a.m.

You know the return or exchange policy. Sizing online always carries some uncertainty. Order from a retailer with a clear exchange process, especially if you’re buying ahead of birth when you don’t yet know your baby’s actual measurements.

For parents ordering a baby sleep sack in Canada, the size chart and TOG guide are the two tools that remove most of the guesswork. Get those two decisions right, and everything else — fabric, print, zipper direction — is just preference.