Almost as important as your sleeping bag’s EN Temperature Ratings is the fit of your sleeping bag. We use our onsite cold chamber to perfect our sleeping bag fit, optimizing spacious luxury with high-performance lightweight warmth depending on the design. So, knowing how critical the fit of your sleeping bag is, how do you pick which fit is best for you? Here’s a closer look at sleeping bag size, shape, and fit, so you can better determine what kind of sleeping bag is best for you.

Sleeping Bag Length

Sleeping bags are sized by their length, and though this may seem obvious, the correct length for your bag should correlate directly with your height. For example, if you’re 6 feet tall, you should be sleeping in roughly the same length bag.

However, don’t think that a 6-foot sleeping bag should fit like a glove. A 6-foot sleeping bag will actually measure roughly 6-foot 8-inches long, giving a 6-foot tall person the extra room needed for a correct fit. Why the extra room? When we lay flat, our spines decompress, our feet fall forward and our bodies spread out. As a result, sleeping bag designers compensate for this by adding a few extra inches to the length.

In an effort to eliminate all possible space, choose a sleeping bag size with an appropriate length for you. Therm-A-Rest sleeping bags come in three sizes: small (5 ft. 6 in.), regular (6 ft.), and long (6 ft. 6 in.). Pick the size closest to your measured height.

Therm-a-Rest Parsec Sleeping Bag

Sleeping Bag Shape

The shape of your sleeping bag should reflect the style of camping you’re planning on doing. There are three basic shapes of bags: Mummy, Rectangular, and Semi-Rectangular. We’ll break it down to help you decide which shape best fits your style.

1. Mummy—The most popular shape, the mummy bag has a snug fit that tapers toward the feet, making it the warmest option. This shape allows the least amount of air between you and the insulating wall of the bag, meaning there is less air to heat. Due to its efficient shape, it’s also lightweight and packs easily, making it the ideal choice for backpacking or technical adventures that require packability but also a high degree of warmth. The downside? Room. A mummy bag can be restrictive compared to other shapes.

2. Rectangular—as the name implies, this is a non-tapered design, which is less efficient at heating, but also less restrictive while sleeping. Warm weather car campers often opt for a rectangular shaped sleeping bag due to the freedom of movement they provide. If comfort, not warmth, is your main priority, consider this style of bag.

3. Semi-Rectangular—a hybrid between the mummy and rectangular shape, this is the go-between for fair-weather campers that require warmth, but also desire the extra room for added comfort. While not as warm as mummy bags that can withstand 3 to 4 season camping, a semi-rectangular bag can work for fair-weather trips, and also be efficient enough for shorter backpacking adventures.

sleeping bag fit chart

Sleeping Bag Fit

Our sleeping bags fit is carefully crafted to fit the needs of your adventure. For our Fast & Light customers, the fit is tapered to maximize thermal efficiency and minimize pack size. Our ultralight fit is even further tapered for those counting every single ounce. For more comfort-minded backpackers, our Trek & Travel sleeping bags use our onsite cold chamber to provide the perfect balance of roominess and thermal efficiency, allowing the most comfortable nights under those backcountry stars.

We also realize that some campers are uncomfortable when a bag feels too tight, so to combat this feeling, we’ve added girth to our mummy bags between the hips and shoulders, giving sleepers the freedom to move and wear a jacket in extra cold conditions. The bottom line, however, is that room is a personal preference, but the right balance will increase your bag’s performance.

Finding Your Fit

Like a jacket, the best way to get the right fit is to try them on if you can. It’s important to realize that each brand of sleeping bag, as well as model, will fit differently. So finding the right sleeping bag is a matter of patience and exploration, but with this information, we hope you’ll be able to dial in the perfect fit.

<< Choosing the Right Sleeping Bag: Part 2—Down Vs. Synthetic

Choosing the Right Sleeping Bag: Part 4—Understanding the Underestimated Camp Quilt>>