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Basecamp Guru - Choosing a sleeping bag

Posted by Andy Neil on Aug 30, 2023

Four Steps to Choosing a Sleeping Bag

Choosing a sleeping bag can be a daunting task. Getting started with so many different options and variations can be challenging. This will be one of the most significant investments, along with your tent, for camping or backpacking. We want you to pick the best sleeping bag for your adventures. Whether you are car camping, wild camping or bikepacking, we've compiled this guide to help you narrow your search for your new sleeping bag.

Step 1 - Decide the temperature rating you need

If you are a “fair weather “camper and predominantly car camp during the summer, or if you are a festivalgoer, you will be looking for a breathable summer bag to kick a leg out of to cool off if it gets too warm.  If you enjoy the thrills of summit bagging in the winter, an encompassing bag that limits heat loss is essential. Knowing what temperatures, you will encounter when camping is essential when purchasing a sleeping bag.

 

Almost all sleeping bags will have three given temperatures: the "comfort rating", the "lower comfort limit", and the "extreme limit". The comfort rating is the lowest temperature at which an “average woman” can sleep comfortably in a sleeping bag while wearing light clothing. The lower comfort limit is the lowest temperature at which an “average man” can sleep comfortably in a sleeping bag while wearing a base layer of clothing. The extreme limit is the lowest temperature at which an average person can survive in an emergency situation. You will not have a pleasant night and almost certainly won't get any sleep. The extreme limit should not be considered when choosing a bag.

 

Sleeping bag temperature ratings are standardised by the EN13537 rating, all reputable sleeping bag manufacturers use this independent standard to inform the end user better.

 

People with differing metabolisms feel the cold differently. Some of us will 'sleep warm' and others will 'sleep cold' - a knowledge of our own tendencies will also inform our decision. If you are a man and the lowest temperature you expect to use the bag in is 0C, then bags with a 0C Comfort Limit are the starting point, but if you are a 'cold sleeper', you may want to go for a -2C or even -5C bag.

The importance of Sleeping mats and R-value.

A sleeping mat is as essential as a sleeping bag to ensure a good night's sleep. It provides comfort and, more importantly, insulates you from the cold ground. A mat's insulating properties are measured in R-value. The higher the R-value, the better the insulation. Sleeping bags will only perform at the advertised temperature with a warm enough mat. A mat with a higher R-value is not necessarily heavier or bulkier, so there is no downside to using a winter-rated mat in the warmer months.

 

Step 2 - Decide on the type of filling you want - Down or Synthetic

All the bags we sell will be filled with Synthetic or Down insulation. Each has its own merits.

 

Synthetic insulation is made from man-made materials like polyester or nylon. It is water-resistant and easy to care for. Synthetic insulation has improved greatly in recent years from being heavy and bulky to closely mimicking down attributes. It does not pack down as small as down and will have a heavier warmth-to-weight ratio, but it is less expensive than down insulation. 

 

If most of your camping is done on campsites that you drive to, or you often camp in a bivi bag or in damp conditions, a synthetic bag is an excellent choice. 

 

Down insulation is made from the soft feathers of geese or ducks. It is warm, lightweight, and highly packable, making it a good choice for bags when weight and pack size are an issue. Most Down is treated with a Hydrophobic coating, which helps it repel water, but if it does get wet, it loses its ability to loft and trap heat. It can be harder to care for and must be washed and dried with care, but it will outlast synthetic insulation if looked after.

 

If you carry your gear from campsite to campsite or do a spot of wild camping, a lightweight, warm bag that packs down small is key. Down insulation should be considered when aiming to make your pack as light as possible, it has a far better warmth-to-weight ratio over synthetic bags and packs down much smaller; however, it will tend to be more expensive.

 

We describe the quality and quantity of the down inside the bag by quoting the bag's fill power (FP) and fill weight (FWt). Fill power is a measure of the quality of the down. The higher the fill power, the more loft the down has, which means it traps more air and provides better insulation. Fill weight measures the amount of down in a sleeping bag. The more down in a sleeping bag, the warmer it will be. However, more down also means a heavier sleeping bag. Two sleeping bags with the same fill weight but different fill powers will have different warmth ratings. A sleeping bag with a higher fill power will be warmer than one with a lower fill power, even if they have the same fill weight.

Step 3 - Decide what size and shape you need

The insulation in the bag keeps you warm by trapping a layer of still air around your body, thus reducing heat loss by Convection. To eliminate all possible “free space”, choose a sleeping bag that is an appropriate length for you. Bags tend to 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.

 

Mummy sleeping bags vs rectangular.

Mummy sleeping bags are more compact and lightweight than rectangular ones, making them ideal for backpacking and camping. They also tend to be warmer than rectangular sleeping bags, as they wrap around your body more closely. However, they can be more restrictive and less comfortable, especially if you are a side sleeper. Rectangular sleeping bags are roomier and more comfortable but are also bulkier and heavier. They are a good choice for car camping or other activities where weight is not a major concern.

 

Women-specific bags

There are subtle differences between men's and women's sleeping bags, down to biological and physiological variations. Most major sleeping bag brands produce bags specifically for men and women, but some still produce unisex bags. Women's specific bags are generally shorter than men's and have a more tailored fit to better conform to a woman's body. Some Women's specific bags have more down in critical areas such as the feet, which are more susceptible to cold. Biologically speaking, women tend to sleep colder than men, so often, more down is used in the bag to make up for the difference in the temperature rating. 

 

Quilts

A popular alternative to sleeping bags is quilts. With much less material needed, there is an instant weight saving and, in mild conditions, you may not want the full body wrap of a traditional sleeping bag. Paired with the right mat for insulation from below, quilts can be used year-round with a few adaptions to your system. 

Step 4 - Construction and Features

Once you have narrowed you’re your needs and wants from the first three steps shown, you may want to think about some of the finer points such as the specific design features included in the bag. Features may not make your sleeping bag warmer, but they may make it easier to get in and out of, easier to regulate temperature or protect you against draughts and moisture, all important considerations.

 

Shell fabrics and DWR - The outer layer of a sleeping bag protects the inner insulation from the elements. It will typically be made of ripstop fabric, either nylon or polyester. It will tend to have been treated with a DWR (Durable water-repellent) coating. Which is added to fabrics at the factory to make them water-resistant. A DWR helps the fabric shed water and allows it to dry quicker if the bag does get wet.

 

Sleeping bag construction - Compartments are needed to keep the insulation in place; otherwise, it would all migrate to the bottom of the bag.

 

- Sewn through - the most uncomplicated method where lines of stitching are sewn to join two fabrics, creating long pockets for the down to be fed into. The pinch points at the stitching prevent the down from lofting fully in these areas, and potential cold spots along the stitch lines can appear where there is no insulation. This isn't as much of a problem with bags intended to be used in warmer conditions. 


- Box Wall Construction - Overcomes the disadvantages of sewn through by stitching a third piece of material between each layer of fabric to create 'pockets' for the insulation with walls. This eliminates pinching of the insulation at the stitch lines and allows the down to loft fully.


Zips - Most sleeping bags are fitted with a full-length zip that runs the length of the bag almost to the foot. These zips usually have a slider at each end, allowing you to ventilate the bag from the foot end if it's too warm for the conditions. Some manufacturers make bags with zips on either the left or the right-hand side. A left-hand zip is by your left hand as you lie in the bag on your back. A left-hand zip is suited to a right-handed person as the right arm comes across the body to unzip it, whereas using the left hand to unzip a left-handed zip would be trickier. Some manufacturers only make bags with left-hand zips.

 

Some bags don't have any zip at all to save weight. These are difficult to get in and out of. Some bags have a short zip on the side or top of the bag - again, this feature saves weight. Access in and out of the bag is fine, but it does not give any options to vent the bag at the bottom. Baffles and draft collars - Zips, are a potential cold spot, an area where cold air outside of the bag can get inside so, apart from very lightweight bags designed for summer use, most zips are insulated using a baffle or draft collar - this is a down-filled strip that sits across the zip, eliminating it as a cold spot. Sleeping bags for colder conditions will also have a shoulder baffle. This prevents draughts and stops air from circulating out of the bag, taking the warmth with it.

 

 

 


Choosing a sleeping bag can be a daunting task. With so many different options and variations, it can be difficult to get started. This will be one of the biggest investments, along with your tent, for backpacking so it's important that you make the right choice for what you need. We genuinely want you to pick the best sleeping bag for your adventures so we've put together this simple guide to help you narrow down the options for your search.