Embarking on the quest for the perfect sleeping bag is an exciting venture, and fortunately, it’s not as complicated as it may seem. With so many different options to choose from, it’s just a matter of finding the right match. Investing in the right sleeping bag is going to provide comfort and quality sleep in the great outdoors. So which is best, mummy vs rectangular sleeping bag?
A new sleeping bag brings both anticipation and, at times, a considerable initial cost investment. In this guide, I’ll explore the world of sleeping bags, ranging from mummy sleeping bags to rectangular ones, not to mention the versatility of relaxed mummy and double bags. Each allows for different preferences and needs, ensuring that your next adventure in the great outdoors is accompanied by the perfect sleep system.
Let’s dive into these different sleeping bag types, understanding their unique features and discovering the best choice for your individual preferences.
Complete Guide to Choosing the Right Sleeping Bag: Mummy Vs Rectangular Sleeping Bags

This blog post is supposed to act as a guide for selecting the perfect sleeping bag. Before you get into choosing the perfect sleeping bag, you need to figure out what you plan on using the sleeping bag for. Each type offers something different so you’ll need to eventually choose between a mummy and a rectangular sleeping bag.
This guide includes the following information to make choosing the right bag easier:
1. Understanding Different Types
I will share the various sleeping bag types, including standard mummy sleeping bags, rectangular bags, relaxed mummy options, and double sleeping bags. Each type has unique features and caters to different sleeping styles and outdoor scenarios.
2. Type of Bags Based on Your Own Personal Needs
Finding the perfect bag requires knowing what you will be using the sleeping bag for. Whether you’re a side sleeper, back sleeper, or someone who values extra room, this guide will help match the type of bag with your individual needs. Are you going to be car camping, backpacking, or traveling with your sleeping bag?
Follow along to discover what type of bag is best for you!
Different Sleeping Bag Shapes

Let’s first explore the different sleeping bag shapes available. Each sleeping bag type has a variety of purposes as well as some pros and cons. Each sleeping bag is best suited for different circumstances, but we will cover that a little later on!
Rectangular Bag
For the Side Sleeper Seeking Space

If you’re someone who loves stretching out and changing sleeping positions without feeling confined, the rectangle sleeping bag might be your ideal pick.
These classic sleeping bags are perfect for car and tent campers because they provide ample space. In taking up more space, they don’t pack down very small.
Mummy Bag
Harness Your Body Heat with the Mummy Shape

The mummy shape sits snugly on the body. There are minimal gaps between your body and the sleeping bag making the bag a great choice for people looking to camp in cold climates. The mummy shape is the best option when you’re prioritizing warmth and insulation. Bonus points is that mummy sleeping bags include a stuff sack making packing a breeze.
Mummy-shaped bags have less room but are great for trapping warm air and minimizing heat loss.
Relaxed Mummy Bag
Semi-rectangular Bliss for Side Sleepers

My personal favorite is the relaxed mummy sleeping bag.
If the snug fit of the mummy sleeping bag is too constricting, a relaxed mummy might be the perfect sleeping bag for you. This is also a great choice if you’re still trying to focus on insulation and packability! With a semi-rectangular design, it caters to people who appreciate a bit more wiggle room.
This one is all about personal preference for a comfortable night’s sleep.
Double bags
Personal Preference and Plenty of Space

If you have storage space and want to have a large combined sleeping bag with extra space, a double bag might be for you. A double sleeping bag is usually the size of a full blanket, making it easy to snuggle up in between the bag with a partner or pet. With the spare room, it is best used as a car camping sleeping bag.
If a double bag sounds like something you would be interested in but also want to backpack, consider purchasing a mummy or relaxed mummy that has zipper compatibility with another bag. This way you can combine two bags when you’d like or stick with a single bag when needed.
In the next section, we will talk about what scenarios to consider when choosing a sleeping bag that will work best for you. It is important to not think short term, but long term with your camping and outdoor goals as this could alter what sleeping bag would be best for you.
What to Consider When Picking a Bag

When it comes to choosing a sleeping bag that works best for your needs, it is important to consider your current needs and potential future needs. The features of different sleeping bags will help determine what is best for each situational need.
Let’s look through some of the different features to determine when that feature comes into play and what type of bag would be best.
Compact Mummy Thermal Duck Down Sleeping Bag
Synthetic vs Down Fill
When it comes to choosing a sleeping bag, two of the major factors that you will need to decide on are synthetic or down-filling for your sleeping bag. While both mummy sleeping bags and rectangular sleeping bags come in synthetic and down options, there are circumstances in which synthetic and down would be more applicable depending on use.
Synthetic Fill

Synthetic Insulation is extremely common and is NOT made from animal byproducts like down is, making it a popular fill. Synthetic fill has a number of pros and cons as follows:
Pros:
Synthetic insulation is fantastic at retaining warmth and insulating the body.
- It is great in colder conditions and on par with the higher quality down.
- Retains its insulating properties when wet, making it a reliable choice in unpredictable weather. If you find yourself camping in predominantly wet conditions, synthetic will likely be the choice for you.
- Synthetic Insulation is versatile in bags. Regardless of the shape of the bag you purchase, there will be options for synthetic insulation.
Cons:
While there are cons to synthetic insulation, consider them carefully.
- Synthetic insulation is often bulkier than down. To provide the same amount of heat retention as some of the higher-quality down sleeping bags, significantly more filling needs to be used.
- Insulation Loss is also a problem with synthetic sleeping bags. Fill is easily lost from the lightweight material surrounding the bag which decreases the heat retention over time.
With synthetic bags, it is important to keep in mind if they will be great for long-term use and will hold up well with the many different activities you plan on using your sleeping bag for.
Down Fill

Down insulation relies heavily on the quality of the down and the amount of fill. When purchasing a bag with down insulation, paying attention to the amount and quality is going to be of utmost importance on top of weighing the pros and cons.
Pros:
When choosing a down sleeping bag, there is a lot of choosing the temperature rating of your sleeping bag.
- The warmth-to-weight ratio is unmatched, meaning that a warmer down sleeping bag will likely be significantly lighter in weight than a synthetic sleeping bag with a similar temperature rating.
- The available temperature rating of a down sleeping bag is widespread. Down sleeping bags offer a range of temperature ratings from negative degrees to positive 30s. They are an ideal candidate for people looking for a bag that can be used in a variety of seasons.
- Down has a variety of fill power. The fill power helps determine the quality and insulating capabilities of the down fill. A down fill of 750 and high is of exceptional quality.
Cons:
In comparison to synthetic insulation, down fill fares poorly in wet conditions.
- In wet conditions, down insulation loses its insulating capabilities.
- Down absorbs humidity, which means that even if it is not actively raining, the water in the air will negatively impact the down insulation.
- The drying time of down insulation is significantly longer than synthetic insulation. Once your down sleeping bag is wet, it is challenging to dry again in the backcountry.
Down bags have some serious pros for both cold weather camping and warm weather in summer months. However, if camping conditions are wet, down bags will fall short of synthetic bags.
Intended Use: Camping or Backpacking

When considering the type of bag that is best for you, it is important to consider what bag is best for your activities. Separating into camping and backpacking implies two distinct types of outdoor recreation: one with lots of available storage and useability and one with limited storage and specific usability.
Camping

Whether you are tent camping or car camping there is a certain amount of space that is available to you for travel, which is the size of your vehicle.
This means you can use anything from a mummy sleeping bag to a double sleeping bag, depending on personal preference.
However, if you are planning on using sleeping bags when you car camp, you should also consider if you intend to use those same sleeping bags for backpacking.
Backpacking

Backpacking is limited to minimal space. Your sleeping bag needs to be compact as does the additional gear that you’re bringing on your trek. So when picking between a mummy vs rectangular sleeping bag, space is going to be extremely important.
Sleeping bags that take up excess room and are heavier than normal, will need to be left behind. This makes a down, mummy sleeping bag the optimal choice for backpacking.
If you care to have a double sleeping bag in the backcountry, you and your partner can purchase zipper-compatible bags that zip together. A standard double sleeping bag is much too large and heavy to carry into the wilderness.
Temperature

The temperature that you intend on using your bag is going to quickly determine what shape of sleeping bag you need for your outdoor adventures. Since different sleeping bag styles retain different heat values and fare better in a variety of temperatures, being considerate of all will be most beneficial.
Even if you predominately camp in fair temperatures, but want to eventually camp in snowy and freezing temperatures, this is something to consider with your purchase.
How to Read Temperature Ratings of Sleeping Bags
I will be honest, the temperature rating of sleeping bags should be straightforward. When a bag says that it is rated for 15 degrees Celsius, it should mean that you will be comfortable using the bag at 15 degrees Celsius, however…that is not always the case.
Women’s Temperature Rating
When it comes to women’s temperature ratings for sleeping bags, the temperature rating is based on comfortability in the temperatures. This means that if a sleeping bag has a temperature rating of 15 degrees for a women’s sleeping bag, most women will be warm enough at that temperature with that particular bag.
Men’s Temperature Rating
With men’s sleeping bags or unisex bags, the temperature on the bag does not reflect the comfortability rating, but rather the minimum temperature that a person should safely be using that sleeping bag in. So a 15 degree sleeping bag in a men’s or unisex bag has the potential of being significantly lacking in insulation compared to a women’s 15 degree bag which is rated on comfort.
What Bag to Get Based on Temperature: Mummy vs Rectangular Sleeping Bag
While a 0 degree bag will be way too hot camping in 40+ degree weather, there is always the option to unzip and take off a few layers. Unfortunately, when it comes to 0 degree weather, a 40 degree bag would not provide enough insulation.
As someone who uses their sleeping bag as a quilt in warmer weather, or ultimately ditches their sleeping bag altogether in the summer, I lean more towards buying a significantly warmer sleeping bag if I will be experiencing cold temperatures than adding additional layers if I “happen” to experience colder temperatures.
Mummy Sleeping Bags tend to have a lower temperature rating available.
How to Increase the Warmth of Your Sleeping Bag
When choosing between a rectangular and mummy sleeping bag, it is hard to choose between comfortability and practicality. However, you do have options that will help increase the overall temperature of your sleeping bag regardless of which shape you choose.
Sleeping Bag Liner

Whether you are using a mummy vs rectangular sleeping bag, there is a sleeping bag liner that will fit your bag. Sleeping bag liners are produced to fit the sleeping bag shape that you have. Whether you’re using a mummy or rectangular sleeping bag, there are sleeping bag liners available for both.
For mummy sleeping bags, there are a variety of options ranging from fleece to flannel to silk. This is mostly for the purpose of minimizing the frequent washing of these sometimes fragile bags.
For rectangular, you still have the option to use the mummy-shaped sleeping bag liners, but there are still rectangular-shaped sleeping bag liners that may be more comfortable.
Sleeping bag liners can add up to 30 degrees of warmth to your sleeping bag, so if you’re sleeping in conditions that are much colder than your sleeping bag allows, adding a cheeping sleeping bag liner to your sleep setup will add significant insulation.
Sleeping Pad R-Value

If you’re sleeping on a sleeping pad, air mattress, or just straight up on the ground, that will impact how warm you will stay when sleeping at night.
A sleeping pad can make a huge difference in your comfort at night depending on what you use. Backpackers know all too well the impact of a sleeping pad with a significant R-value, however, car campers and tent campers used to using air mattresses rarely think about how cold air gets in an air mattress in the wilderness.
Add insulation to your sleeping system by sleeping on an air pad or air mattress with an R-value of 5 or greater.
You can increase the R-value by:
- Adding a blanket between you and the pad
- Adding a Z-pad underneath the mattress
- Increasing the bottom insulation of your sleep system
Air gets significantly colder at night regardless of whether it is confined in an air pad or not, take proper precautions to not cool yourself down further by sleeping on an air mattress with a low R-value.
There are different-shaped sleeping pads, mummy-shaped pads, and rectangular-shaped sleeping pads. A good sleeping pad will make a significant impact on mitigating heat loss.
Let’s look at some sleeping bag recommendations in the next section to get you set up for success on your next camping trip!
Pack It Up
Choosing the perfect sleeping bag isn’t just a monetary investment, it is an investment in your future endeavors. The sleeping bag you choose to purchase will be with you for years to come and provide you with comfort through your adventures. In the debate between mummy vs rectangular bags, the different shapes are going to be a personal preference.
Consider what you need for a good night’s sleep and the type of camping you will be doing. This will impact the type of insulation you will want for your sleeping bag.
The perfect sleeping bag for each of your adventures is out there, you just need to decide what type of adventures you want to go on!
I hope this guide served as some guidance for you with choosing a sleeping bag that works best for you. Whether you’re picking a mummy vs. rectangular sleeping bag, each serves its purpose.