Mummy vs Rectangular Sleeping Bag – Which is Best?

Mummy vs rectangular sleeping bag - which is best for tent camping?

Let’s face it. We all need a sleeping bag, and there are just too many options to choose from. In this article, we will help you make the most important decision: Choosing a Mummy vs. Rectangular Sleeping Bag.

Choosing the right sleeping bag can make all the difference. There isn’t a perfect sleeping bag. The best sleeping bag is a mix of personal preferences, budget, and your style of camping.

Which is better – Mummy vs Rectangular Sleeping Bag

We believe mummy sleeping bags are better than rectangular sleeping bags. The reason is that they are a better fit for our specific needs. We need our sleeping bags to be warm, light, packable, and versatile.

Mummy sleeping bags excel in all of these categories. We often find that REI Outlet has great deals on sleeping bags.

That being said, there are certain circumstances where a rectangular sleeping bag is preferred. This article will detail how these two sleeping bag styles differ when it comes to shape, comfort, warmth, portability, versatility, and affordability.

Mummy vs Rectangular Sleeping Bag – Shape

Mummy vs rectangular sleeping bag - different styles for different types of camping

One of the biggest differences in a mummy vs. rectangular sleeping bag is the shape.

Mummy bags are contoured around the shoulders, tapered at the feet, and have a hood that can be tightened around the head. Most also come with a draft collar that helps keep warm air in the bag.

They tend to be warmer because this shape limits the excess air that is between your body and the sleeping bag insulation, which requires body heat to keep warm. They are more efficient.

Rectangular sleeping bags are rectangular, almost like folding a blanket over oneself. They zip up on one side, but are completely open where your head sticks out.

This shape does not trap warm air as easily as a mummy bag for two reasons:

  1. Warm air easily escapes from the top of the sleeping bag
  2. The rectangular shape means more air has to be kept warm inside the bag in order to maintain a comfortable temperature

In short, when it comes to thermoregulation, rectangular bags are less efficient than mummy sleeping bags. For us, this is one of the main reasons we prefer mummy sleeping bags.

Mummy vs Rectangular Sleeping Bag – Warmth

Mummy sleeping bags are warmer than rectangular sleeping bags. Their tapered design limits the amount of air inside the sleeping bag, which means there is less air to keep warm.

A mummy sleeping bag also traps warm air with its hood and neck baffle, which means less heat escapes.

Rectangular sleeping bags can be made warmer, however they cannot compete with a good mummy bag. You can fill the extra space in your rectangular sleeping bag with extra clothes, blankets, etc. to add insulation and get rid of excess space.

The Winner: Mummy Sleeping Bag

Mummy vs Rectangular Sleeping Bag – Comfort

For most sleepers, a Rectangular Sleeping Bag will feel more comfortable. Rectangular sleeping bags allow for more movement while sleeping. They also accommodate different sleeping styles by allowing you to move around inside the sleeping bag.

They are better for side sleepers, front sleepers, and those who move around a lot at night.

Mummy sleeping bags can feel claustrophobic for campers that are not used to them. The tapered design limits movement and is not ideal for side or front sleepers.

Mummy sleeping bags can also be uncomfortable if you are tall, broad shouldered, or larger than average. It is worth testing your mummy sleeping bag at the store to ensure that it fits your body type.

The Winner: Rectangular Sleeping Bag

Mummy Vs Rectangular Sleeping Bag – Portability

Mummy sleeping bags are more portable than rectangular sleeping bags. Mummy sleeping bags were originally designed in the 1930s for mountaineers, which require extremely light gear.

Mummy bags are extremely light and can be packed down into small stuff sacks. A good down-fill 35F mummy sleeping bag will pack down to the size of a Nalgene water bottle.

Rectangular sleeping bags are usually bulkier and heavier. They are designed more for stationary activities like car camping and emergency use in the home. They are not a great option for activities like backpacking that require gear to fit in limited spaces.

That being said, many retailers like REI and Nemo have begun selling rectangular sleeping bags that share some of the same materials as traditional mummy bags and are lighter weight than the traditional Coleman-style rectangular bags.

The Winner: Mummy Sleeping Bag

Mummy vs. Rectangular Sleeping Bag – Versatility

Rectangular sleeping bags are more versatile. Mummy sleeping bags can only be used one way, with one person inside zipped up tight.

A rectangular sleeping bag can be unzipped and used as a blanket, ground cloth, or zipped together with another similar sleeping bag to make a double sleeping bag.

The Winner: Rectangular Sleeping Bag

Mummy vs. Rectangular Sleeping Bag – Affordability

The sleeping bag industry has come a long way. You can now find both mummy sleeping bags and rectangular sleeping bags at the same price points with the same materials.

That being said, it all comes down to performance. If you are looking for an extremely warm and packable sleeping bag, then you will likely be choosing from higher-end mummy bags, which are more expensive.

The Winner: Rectangular Sleeping Bag

Mummy vs. Rectangular Sleeping Bag – Final Decision

Rectangular vs. mummy sleeping bag - staying warm at night while camping
Mummy bags being used to camp without a tent with nighttime temperatures below freezing

Your sleeping bag must meet the rigors of your expected use.

If you are cold weather camping, backpacking, mountaineering, canoe tripping, or doing anything that favors lightweight gear, then you will want to look at a mummy-style sleeping bag. Their lighter weight and added warmth will pay dividends on those colder nights in the mountains.

If you are car camping, using it for sleepovers at home, RVing, or doing anything that is stationary and does not require hiking, then a rectangular sleeping bag is going to work. You will be able to get away with a bulkier sleeping bag that is a bit more versatile and often far more affordable.

Sleeping Bag Frequently Asked Questions (FAQs)

Are there any other sleeping bag options besides mummy and rectangular sleeping bags?

Yes. There are semi-rectangular bags and double bags.

Semi-rectangular bags are mummy-shaped bags that also have some of the extra shoulder and legroom that is standard in rectangular sleeping bags. It is a hybrid option that provides a good compromise. Big Agnes is a popular brand.

Double bags are larger rectangular sleeping bags that are made for two people. They allow a couple to capture each other’s heat loss. They are great for car camping, but not for backcountry adventures.

What type of sleeping bag insulation is best?

Sleeping bags come with two types of insulation: down fill and synthetic fill. The type of insulation can have a big impact on the performance and cost of a sleeping bag.

Down fill, made with goose feathers, is generally lighter weight, warmer, and more packable. Down bags perform well in all temperatures, however do not perform well in wet weather.

A down sleeping bag is generally more expensive than a comparable synthetic sleeping bag due to the higher cost of down insulation.

Synthetic insulation is slightly heavier and does not pack down into its stuff sack as tightly. Synthetic bags perform better in wet conditions.

As a general rule, most rectangle bags are made with synthetic insulation and mummy shaped bags have the option of either down or synthetic materials.

How can I increase the warmth of a good sleeping bag?

There are two ways to increase the warmth of a sleeping bag: sleeping pads and sleeping bag liners.

You should never sleep on the ground without some type of ground insulation between your sleeping bag and the ground. The best way to achieve this is with a sleeping pad.

A sleeping pad will make a good sleeping bag even better by providing insulation from the cold ground and preventing ground moisture from reaching the sleeping bag. You can get both a rectangular shaped sleeping pad and mummy-shaped pads.

A sleeping bag liner can add additional insulation to a sleeping bag. It also helps to fill up the excess air in the bag, which helps to prevent cold spots.

Sleeping bag liners come in a variety of sizes and materials. Fleece and silk are common. Mixing materials, like synthetic insulation with a down inner sleeping bag, can add warmth and help with moisture management.

What do sleeping bag temperature ratings mean?

Sleeping bag temperature ratings provide an estimate of your sleeping bags ability to keep you warm. There are two main ratings used to compare sleeping bags:

  • Comfort rating indicates the temperature at which a cold sleeper might feel comfortable. This is the temperature rating brands use on women’s bags.
  • Lower limit rating (which is always lower than the comfort rating) indicates the temperature at which a warm sleeper might still feel comfortable. This is the temperature rating brands use on men’s bags.

So a 30F with a lower limit rating will keep a warm sleeper comfortable down to 30F. We own two mummy sleeping bags each, a 35F bag and a 0F bag. They cover most temperatures we camp in. If it is freezing, we can use the 35F bag as a liner inside the 0F bag and stay comfortable down to about -20F!

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