Mummy Sleeping Bags vs Rectangular Sleeping Bags: a Comparison

Imagine this: you've bought a great tent, top-quality cooking equipment, and spent more money on a flashlight than you ever imagined you would. You're almost ready to start filling your backpack with all the camping essentials. There's just one thing missing: a backpacking sleeping bag

With so many options on the market, how do you know which sleeping bag style is right for you?

Sleeping bags come in a variety of shapes and sizes. There are plenty of options on the market to suit your needs, whether you're a backpacker, a seasoned camper, or a hardcore mountaineer. 

In this article, we'll explore the great mummy vs rectangular sleeping bag debate, and provide you with all the information you need to choose which style will best suit your next adventure. 

What's the difference between Mummy and Rectangular sleeping bags?

Before we delve into the ins and outs of choosing between mummy vs rectangular sleeping bags, let's take a look at what exactly it is that differentiates them in the first place. 

Rectangular sleeping bags

Rectangular Sleeping Bags

Rectangular shape sleeping bags are the most traditional kind. They're likely the ones you've used before on family camping trips or sleepovers at friends' houses. Roomy, warm, and comfortable, rectangular sleeping bags are extremely versatile. 

Rectangular shaped sleeping bags give you plenty of space to toss and turn during the night, however, due to their spaciousness, they don't tend to retain as much heat as other types of sleeping bags. This makes them popular among car campers embarking on summer camping trips where the days are warm and the nights are cool. 

Hint: A rectangular sleeping bag can be unzipped and used as a comforter on hot and stuffy nights!

Mummy sleeping bags

Mummy Sleeping Bags

They feature hoods and are shaped to adapt to the contours of the human body. Their design doesn't account for much extra space for moving around during the night, instead, you're likely to roll with the sleeping bag during the night.

Their fitted shape offers better insulation than other sleeping bag shapes and will keep you cozy and snug in the coldest of weather conditions. Sleeping bags with this shape are a popular choice for more seasoned campers, backpackers, and cold-temperature trips. We'll take a closer look at the science behind heat retention in a mummy sleeping bag later on in this article. 

Choosing between Mummy and Rectangular Sleeping Bags

1. Function

When comparing mummy vs rectangular sleeping bags, the first thing to consider is the function.

Obviously, warmth and roominess are your main priorities when it comes to choosing the best sleeping bag to suit all your camping needs.

A rectangular sleeping bag shape isn't designed to provide high levels of heat insulation but does offer lots of room to move. On the other hand, mummy bags will provide less room to move but offer a better sleeping bag temperature rating. 

Think about the type of trip you're embarking on and what your specific needs are. If you're sleeping under wintry skies then the best mummy sleeping bag with a better temperature rating is a good option. Adversely, rectangular sleeping bags are designed for use during warmer climates and are ideal for general use, car camping, and summer holiday adventures. 

2. Comfort 

A great comfort rating is one of the main considerations when deciding between a mummy bag vs rectangular sleeping bag. 

If you're always kicking your partner in your sleep, or often wake up with your head at the other end of the bed; then a rectangular sleeping bag might be your best option. Rectangle-shaped bags provide more space for movement during the night. However, the extra space they provide means they're not known for their insulating properties. 

In comparison, mummy bags are contoured to the body and their design features a highly tapered foot box and area for legs. This means they offer more width at the hip and shoulder areas of the sleeping bag, and a fitted hood area with a drawcord for tightening. They also often feature built-in pillows to provide extra comfort and save you from having to pack extra pillows!

3. Warmth 

It goes without saying that one of the most important things about a sleeping bag is how warm it is. The last thing you want is to wake up shivering in the middle of the night! A sleeping bag's heat retention ability can make or break a good night's sleep.

Are you wondering why are sleeping bags mummy-shaped? It's all down to warmth. This style sleepings bags are more efficient when it comes to warmness, as they expose only the mouth and nose of the sleeper. The tapered design of a mummy sleeping bag increases insulation and reduces the amount of air circulating around the body while keeping warm air inside. This means less air gets pushed out of the sleeping bag as you shift during the night, and less body heat is lost.

For this reason, models with a mummy shape are designed to keep you warm in cold weather conditions.

Rectangular bags provide heat and roominess for people who move a lot during the night, however, they're most suited for temperatures above freezing as their shape doesn't allow for the same levels of insulation as a mummy-style bag. That being said, there are some rectangular bags that are rated for more adverse weather conditions, but they tend to be much heavier and bulkier than others that offer the same levels of sleeping bag insulation. 

Extra considerations for warmth

Type of insulation

The type of insulation in the sleeping bag also contributes to how well it'll perform in cold-weather conditions. They can either feature goose down or synthetic insulation, the former being lighter and warmer, but more expensive. Synthetic insulation is usually more affordable but is often heavier. 

Sleeping pad

Sleep pads with a high R-Value will provide better heat retention and prevent heat loss from the ground.


You need to ensure you bring the right clothing to suit the temperatures you'll be camping in. Thermal gear is vital for cold-weather camping trips for better heat retention. 

4. Price

When choosing the right type of sleeping bag, price definitely plays into the decision making process. A mummy bag will tend to be higher-end and more expensive than a rectangle bag. However, a lower end mummy bag that doesn't offer as much warmth will often be priced similarly to a regular rectangle bag. 

5. Pack size

For backpacking

If you're a backpacker looking for a backpacking sleeping bag for your next worldly adventure, we think investing in a mummy-shaped bag is the way to go. This is because they're often lighter and less bulky than other styles, meaning they have a smaller pack size and can be easily slotted into a backpack. 

In comparison, rectangular bags are a great choice for people who go on car camping trips where warmth, weight, and pack size aren't as high of a priority. The bags fit nicely in any car. When you don't have to carry a sleeping bag around with you or worry about the cold, a rectangular bag can perform just as well as a mummy sleeping bag for car camping - especially if you're prone to tossing and turning during the night! 


1. What are mummy sleeping bags best for?

When it comes to sleeping bags, mummy bags are suitable for every kind of camping trip. That being said, they're best suited to cold-weather trips due to the fact that they provide more warmth than rectangular models. 

2. Are mummy sleeping bags uncomfortable?

Although they might sound more uncomfortable, as you don't have much space to move around, this isn't the case. In fact, people often find mummy bags more comfortable than another shape due to the fact that it keeps you warm and snug throughout the night, and won't result in heat-loss from movement. 

3. What are the 5 types of sleeping bag?

Choosing the right sleeping bag all depends on what you're looking for. The type of sleeping bag you choose should provide warmth, comfort, and portability to ensure you get a good night's rest.


Traditional style sleeping bags provide plenty of room to move around but tend to be on the heavier, bulkier side. Rectangular bags are prone to heat-loss by movement. Great for car campers and summer camps. 


Mummy style bags feature a tapered fit to conform to the contours of the body to provide better heat retention. Excellent for use when the temperature is colder.

Semi-rectangular (also called barrel)

These models are similar to mummy bags but don't completely conform to the user's body shape. So mummy or barrel? If you're looking for a balance between the coziness of a mummy bag and the roominess of a rectangular one, we suggest a barrel-shaped sleeping bag. 


Typically wider versions of traditional rectangular bags that are designed to accommodate two people instead of one. 


Smaller, shorter, and usually cheaper versions of adult models. 

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