Everything Motocampers Need to Know About: SLEEPING BAGS

A frigid night of sleep can ruin even the most epic day of riding, but finding the best sleeping bag for motorcycle camping isn’t always easy. Down vs. synthetic? Mummy vs. quilt? What does an ISO “Comfort Rating” even mean?

This guide breaks down everything you need to know—from temperature ratings to packed size—to choose the right sleeping bag, and ensure you wake up warm, rested, and ready to rip it in the morning.

How Does a Sleeping Bag Work?

Before you buy a sleeping bag, it’s worth taking a second to understand how they work. (I used to work for a sleeping bag company, Valandré, so I’m not just bullshitting here.) Here’s a two-step breakdown.

Step 1: The fluffy material inside your bag—whether it’s natural down or a synthetic fill—expands in the small compartments (baffles) that it’s sewn inside of, creating small pockets of air.
Step 2: Unless you’re a vampire or zombie, your body naturally radiates heat. This heat then warms the air trapped in these pockets. This cloud of warm air forms a protective barrier, slowing the rate at which your body heat escapes into the colder environment outside. Your sleeping bag's outer shell will stop this trapped warm air from being stripped away by wind.

If you surf or dive, then you’ll realize it’s a similar process to how a wetsuit works. Essentially, you’re your own furnace. Your sleeping bag is just insulation. This is also why a sleeping pad is so critical—your bag insulates you from the air around you, your pad insulates you from the cold ground beneath you.

Sleeping Bag Shapes

Sleeping bags come in different shapes. The two main shapes are mummy bags and rectangular bags. Most other bags will sit on a spectrum between these two shapes.

Mummy Bags

Mummy bags are the most technically advanced and popular shape used in modern sleeping bags. Like an Egyptian sarcophagus, a mummy bag is anatomically tapered, so it’s wider at the shoulders and narrows down to a snug footbox, with a form-fitting hood that you can cinch around your head. This minimizes empty air space, meaning your body has less area to heat up, which makes it the warmest option for its weight. The Big Agnes Torchlight is one example of a mummy bag. 

Pros: Best warmth-to-weight ratio, most thermally efficient, packs down the smallest.
Cons: Can feel restrictive or claustrophobic for restless sleepers or those with broader builds.
Best For: Most motocampers, especially those for whom small packed size is important, or those riding in cooler shoulder seasons.

The Big Agnes Torchlight is a good example of a mummy bag.

Rectangular / Semi-Rectangular Bags

Often called “comfort” or “classic” bags, rectangular sleeping bags are… rectangular. This means they offer a roomier fit. A true rectangular bag can often be unzipped completely, and function as a quilt. Semi-rectangular bags, like the Traveller Down from Sea to Summit, offer a compromise, with more room than a mummy, but more thermal efficiency than a true rectangle.

Pros: Very comfortable and non-restrictive.
Cons: Heavier and bulkier, far less efficient at retaining heat (due to excess space).
Best For: Campers who prioritize roomy comfort, and have ample space on their bike. Best for warm-weather trips.

Camping Quilts

A camping quilt is essentially a zipperless, backless sleeping bag. The design philosophy is simple: the insulation you lie on gets crushed and becomes useless, so why carry it? A quilt provides an insulated top layer and sometimes uses a system of straps to connect to your sleeping pad, which provides the insulation from below.

Pros: Ultralight and compact.
Cons: Can be drafty if not sealed properly around the sleeping pad; requires a good insulated pad to function.
Best For: Space and weight-obsessed motocampers, restless sleepers who hate feeling confined, and anyone looking for a versatile, minimalist sleep system.

Sea to Summit's Traveller Down Bag looks like a classic camping quilt, but can be transformed into a sleeping bag using an integrated zipper.

The Key Parts of a Sleeping Bag

Hood: You lose a tremendous amount of heat through your head, so a well-designed hood is critical for staying warm. On almost all mummy (and some semi-rectangular) bags, the hood will be anatomically shaped and have a cinch cord. This allows you to zip it snug around your face, trapping body heat and creating a cozy cocoon on cold nights. Not all sleeping bags have hoods, but a bag without a hood should only be used in warmer weather.

Draft collar: Also called a “yoke,” this is an insulated tube that drapes around your neck and shoulders inside the bag. Think of it as a gasket. When you move around at night, pockets of warm air can escape from the main opening. A draft collar seals this opening, trapping the warm air inside with you. While collars aren’t important for warm weather bags, they’re a must-have feature for any bag that’s intended for cold conditions.

Zipper & draft tube: Zippers are a major weak point for heat loss. To combat this, many sleeping bags have a full-length zipper draft tube—an insulated flap that runs along the inside of the zipper, preventing cold air from seeping through the teeth. Also, look for anti-snag zipper designs to prevent frustrating fabric jams in the middle of the night (or your zipper tearing a hole in your bag when you zip it open or shut too quickly). Zippers are often offered in “left” or “right” side configurations, allowing two compatible bags to be zipped together.

Footbox: Cold feet ruin a night's sleep. A good footbox is designed to be roomy enough for your feet to rest in a natural position without compressing the insulation (which creates cold spots). Many are shaped with a trapezoidal or anatomical design to allow for this extra space, while remaining thermally efficient.

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Sleeping Bag Temperature Ratings

Almost all sleeping bags are accompanied by a number in degrees Fahrenheit (or Celsius, depending on the bag’s manufacturer).

Older sleeping bags were measured using the EN (European Norm), but most modern sleeping bags are tested by the ISO (International Standards Organization). A sleeping bag will typically be given two temperature ratings, a Comfort Rating and a Lower Limit Rating. The latter (lower) metric is the one you’ll usually see in a sleeping bag’s name, but if you look at a bag’s specifications, you’ll see both ratings.

Comfort Rating: This is the temperature at which a “standard woman” or a “cold sleeper” is expected to sleep comfortably in a relaxed position. For most people, this is the most important number to consider.
Limit (or “Lower Limit”) Rating: This is the temperature at which a “standard man” or a “warm sleeper” can sleep for eight hours in a curled-up position without waking. This is often the number used in the bag's name (e.g., a “20°F bag”), but it can be optimistic for some users.

Why do women’s and men’s bags use different ratings?

The different ratings are based on physiology. On average, women tend to have a lower metabolic rate, meaning they produce less body heat while at rest, so they “sleep colder” than men.

How to use sleeping bag temperature ratings to choose your bag

Think about the coldest realistic temperatures you'll encounter on your trips. A good rule of thumb is to choose a bag whose Comfort Rating is at or below the lowest temperature you expect to camp in. When in doubt, always err on the side of warmth. It's far easier to unzip a warm bag on a mild night than it is to shiver through a cold one. For 3-season motorcycle travel across varied elevations, a bag with a comfort rating between 20°F and 30°F is a versatile and reliable choice.

TLDR; A little extra warmth is rarely a bad thing. 

Just keep in mind that a bag’s rating isn’t a guarantee, and it isn’t the only factor at play. A wide range of other factors will affect how you'll really feel once you're outdoors, including your sleeping pad, what you wear sleeping, humidity, wind, and your metabolism.

Sleeping Bag Fill: Down vs. Synthetic

Your bag’s fill is what traps your body heat, and the choice between natural down and man-made synthetic insulation is one of the most important you’ll make. In short, it comes down to a trade-off between performance and cost.

Natural Down

Natural down, typically harvested from ducks or geese, offers an unbeatable warmth-to-weight ratio and is incredibly resilient, able to be compressed down to a tiny size and still puff back up to its original loft for years. For motorcycle campers, the compressibility and superior warmth is down’s greatest asset. Natural down saves a ton of space in a pannier or duffel bag. The main issue with natural down is that it’s (usually) more expensive than synthetic options.

Pros: Warmth-to-weight ratio, compressibility
Cons: Expensive

NOTE: It’s worth mentioning that down doesn’t do well with water. When soaked, it takes a while to dry out. Modern hydrophobic treatments help, but in a head-to-head comparison, a fully soaked down bag isn’t going to dry out as fast as a synthetic alternative. On a multi-day backpacking (on foot) trip in a rainy region like the Pacific Northwest, or on a kayaking trip or other adventure where water is a guarantee—this is worth considering. However, as motorcyclists, there aren’t many scenarios where your sleeping bag is going to get soaked enough for this to matter. And if that does occur (unlikely), it’s not hard to ride into town and find a dryer to dry it out.

Synthetic Fill

Synthetic fill is made from man-made polyester fibers, which are engineered to mimic the insulating properties of down. The biggest recommendation of synthetic over down is that (usually) it’s cheaper. If you’re concerned with animal welfare, synthetic may also be a better choice. All down is either live plucked—pulled off the animal while it’s still alive, extremely painful, or harvested after their death, usually as a byproduct from the poultry industry. So even the most sustainable down harvesting methods are taking feathers from a dead animal. The trade-off is bulk and weight; a synthetic bag will often be noticeably heavier and larger when packed, compared to a down bag with the same temperature rating

Pros: Cheap, no ecological concerns
Cons: Heavy, hard to compress, less warmth per gram

For motocampers, the choice is clear: If your top priorities are the smallest packed size, best warmth, and lightest weight, natural down is king. If you’re on a tighter budget, a synthetic bag could be the better choice.

What is fill power?

Fill power is a number that indicates the quality and insulating efficiency of down. (It’s only used to measure natural down, not synthetic fill.) Fill power isn’t a measure of how much down is in the bag, but rather how “fluffy” or lofty the down is. A higher fill power number means the down can trap more air for a given weight, which makes it a better insulator. The most common fill power ratings will range from about 550 to 950.

So, are loft and fill power the same thing?

This is a common question. The terms are very closely related and often used interchangeably, but there is a subtle difference.

Fill Power is the measurement or rating of the down's quality. It's the specific number (800-fill) derived from a lab test.
Loft is the physical result of that quality—the “fluffiness” or thickness of the insulation that you can see and feel. Higher fill power down creates more loft.

Essentially, fill power is the metric that measures the down's potential to create loft. More loft means more trapped air, which means more warmth.

Sleeping Bag Sizes: How Are Sleeping Bags Measured?

Getting the right size sleeping bag is about more than just being able to fit inside. Size is crucial for thermal efficiency. A bag that’s too large has excess empty space that your body has to struggle to heat. A bag that’s too small will compress the insulation as you press against it, creating cold spots. Sizing is typically broken down by length. Also consider packed weight and volume.

Length

This is the most straightforward measurement. Most brands offer their bags in at least two lengths:

Regular: Typically fits individuals up to 6 feet tall.
Long: Typically fits individuals up to 6 feet 6 inches tall.

Some brands also offer “Short” versions, often in their women's-specific bags, designed for people 5’6” and under. You may also find “Wide” sleeping bags, which can be useful if you’re on the larger side, or if you get claustrophobic easily. For a motocamper, it's best to choose the size that most closely matches your own size. Buying a bag that's too long just adds unnecessary weight and bulk to pack on your bike.

Packed Volume

Offering a number in liters (5L) or length and width (8” x 16”), a bag’s packed volume will indicate how much physical space the bag takes up. This is probably the most important metric for a motocamper, because sleeping bags—especially synthetics—are notoriously bulky, and motorcycle luggage space is finite. 

A bag with a small packed volume can be tucked neatly inside a pannier, protecting it from weather and theft while keeping the weight low and centered. A bulky bag must be strapped to the outside, exposing it to the elements. Always compare a bag's packed dimensions to the interior of your luggage. This is where high-fill-power down bags truly shine, offering incredible warmth with a minimal packed footprint.

Packed Weight

This is the total weight of the sleeping bag including its stuff sack. On a motorcycle, every ounce contributes to the total load, affecting balance, suspension performance, and handling. A lighter sleeping bag makes the bike feel more nimble, especially on long tours loaded with food, water, and other gear. A bag under 3 pounds is a great target, with high-performance ultralight models coming in under 2 pounds.

What Sleeping Bag Accessories and Features Should I Look For?

In addition to a sleeping pad and a camping pillow, there are a few accessories that you can look for when you buy your sleeping bag that may come in handy.

Sleeping bag shells: The outer fabric, which is made of either a durable polyester or nylon, has a durable water repellent (DWR) finish to protect the insulation inside the shell from dampness.
Zipper features: Getting a bag with more than one zipper slider makes it easy to adjust ventilation. In addition, some bags prevent zipper snagging by shielding the zipper with a guard along its full length.
Stash pocket: A few sleeping bags offer a handy stash spot for things like headlamp, car keys, or phone.
Stuff sack: A stuff sack is a must-have, but sometimes the stuff sack that comes standard with a bag isn't as good as a dedicated sack you can purchase separately.
Sleeping bag liner: Slipping a soft sleeping bag liner inside your bag helps keep it clean and adds extra warmth when needed. Camping in hot weather? Skip the bag and just sleep in the liner.
Storage sack: Leaving a bag permanently smooshed inside its stuff sack is bad for the insulation, so some bags also come with a larger mesh sack for long-term storage. Alternatively, you can hang your sleeping bag up in your closet or garage.

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