3-season sleeping bags

A high-quality SLEEPING BAG will guarantee a good night’s sleep. It’ll keep you warm, cosy and comfortable, and ensure you’re well-rested for the adventures ahead. From down-filled cocoons to synthetic duvets, here are eight of the best sleeping bags for use from early spring to late autumn.

EN/ISO TEMPERATURE RATINGS

Sleeping bags are commonly graded by the EN/ISO standard, stating temperature ratings as ‘comfort’ (warm enough for the average female), ‘comfort limit’ (warm enough for the average male), and ‘extreme’ (you won’t die, but it’ll be very uncomfortable). To confuse matters, some brands publish their own in-house temperature ratings (eg the ‘Rab Sleep Limit’).

FILL WEIGHT

Fill weight is the amount of down in a bag, measured in grams. The higher the fill weight, the warmer a bag will be. This means that it’s important to check both the fill weight and fill power. A sleeping bag with only 650 fill power down can still be as warm as a bag with 900 fill power down, if it has a higher fill weight (ie more down) inside the bag.

ZIP

A full-length zip makes it easier to get in and out of the bag, and permits venting overnight if you’re feeling hot. A two-way zip works better for this.

WARMTH-ADDING FEATURES

An insulated, adjustable hood can make a big difference in cold conditions, as will a cinched-in shoulder baffle (draught collar) to lock in heat. Extra baffles in a shaped footbed and a baffle over the main zip add warmth too.

WARMTH

Choosing a bag you’ll be warm enough in is tricky. The comfort and lower limits are the best indicators, but they should be used as a guide only. You won’t necessarily be warm at the comfort limit temperature. If you tend to feel the cold badly, give yourself a buffer with the temperature ratings – for example, if you’ll be sleeping at 0°C, choose a bag with a comfort rating of -5°C.

YEAR-ROUND USE

The 3-season category covers a broad range of weights and temperatures. Some campers will opt for a warmer 3-season bag and use it year-round, but it’ll be too warm in spring and summer. Other campers will choose an ultralight 3-season bag ideal for summer, but they may feel too cold in the shoulder seasons. The keenest campers will need three products: an ultralight bag for spring and summer months, a warmer 3-season bag for colder nights, and a fully-fledged winter bag for sub-zero camps.

PACK SIZE & WEIGHT

As you’ll be carrying it up a mountain, aim for a bag with the lowest weight and most compact pack size within your specific temperature and price range.

SIZE & SHAPE

Most bags are available in different lengths and widths, as well as women’s specific models. Bags with a tapered ‘mummy’ style are narrower and cut out cold spots better, but can feel restrictive. Others have a roomier, more rectangular design, which some campers find more comfy.

FILL

Down or synthetic? That’s the dilemma. Choose down for a superior warmth-to-weight ratio, or synthetic for better value, easier maintenance and improved insulation when wet. For ethical reasons, make sure goose or duck down adheres to the Responsible Down Standard.

CONSTRUCTION Most bags use box-wall construction to trap the fill inside brick-shaped pockets (baffles). Larger baffles give more space for insulation to loft, smaller baffles help stop the fill from spreading out.

FILL POWER

Fill power is a rating system for down that measures compressibility and loft (fluffiness) – and gives an indication of its insulating properties. A higher fill power indicates better quality down and a greater warmth-toweight ratio. Synthetic sleeping bags do not have a fill power rating, but are graded in GSM (grams per square metre). The higher the figure, the thicker, heavier and warmer the insulation will be.