At the end of a long day in the hills, it can be bliss to wriggle into a warm sleeping bag. Frequent outdoor users usually own two: one for summer and shoulder season weather and one for the coldest months.

Insulation

There are two insulation types:
Down: The best for weight and bulk. Most down is now treated with a water-resistant coating to maintain loft and prevent clumping when wet. Check the label to make sure the down is dry treated. 
Synthetic: A good option for prolonged damp conditions, lower budgets or where weight is less important. The bags are heavier and less compressible than down for the same warmth rating but are durable, easier to wash and they’ll be warmer when wet through. High-end and budget synthetic bags are available.  

Fill power

The fill power (or loft) of a bag indicates the insulative quality of the down in the bag. Bags with high fill power numbers, e.g. 850FP, use less down to achieve the same warmth as a bag of, say, 600FP which will be heavier and less compressible. The higher the fill power, the more expensive the bag. 

Hood

The more anatomic and better fitting the hood, the warmer your bag will be when pushed to its limit. Hoods should have good loft and a neck baffle to trap warm air. Drawcords should be easy to operate in the dark. 

Fabrics

DWR-treated ripstop nylon or polyester are the most common shell fabrics. With down now usually dry treated, lighter fabrics have made a comeback.

Shape

Mummy bags are the warmest and lightest due to having less ‘dead space’. They vary in size, so it’s best to try a couple to see which suits your body shape. Women- specific bags are shorter and slightly wider at the hip.

Zips

Zips allow ease of entry and ventilation. For maximum warmth and minimum weight, half or three quarter zips are best. A bag with a full length, two-way zip allows for greater ventilation and can sometimes be zipped to another bag.

Baffles

Baffles form the parcels of down and are distributed to place the insulation where it’s needed most. In mid to high-end bags, baffles afor greater loft. On cheaper bags, they’re sometimes ‘sewn through’.

Draft tubes

Insulation-filled draft tubes prevent heat loss through the zip.

Temperature rating

Ratings are approximate, however, bags in this feature have all been tested to the temperature ratings standard EN13537 or, for bags sold outside Europe, ISO 23537-1. The temperatures shown for the following sleeping bags are:

• Comfort: The temperature an adult woman could expect a comfortable night’s sleep.
• Limit: The temperature at which a standard man can sleep for eight hours in a curled position without waking.
• Extreme: The minimum temperature at which a standard woman can remain for six hours without risk of death from hypothermia (though frostbite is still possible).

Responsible Down Standard

All down insulated sleeping bags in this feature adhere to the Responsible Down Standard (RDS), which, among other things, prohibits the removal of down and feathers from live birds as well as the force feeding of birds. Only products with 100 per cent certified down and feathers carry the RDS logo.

Rab Mythic 600 $1499.95
900FP European hydrophobic goose down, down-stabilising chevron-shaped baffles, three-quarter length two-way zip, 10D Pertex Quantum shell and lining, down-filled neck baffle, angled footbox. Temp rating -5°C (comfort), -12°C (limit), -32°C (extreme) Fill weight 600g Weight 885g. www.outfitters.net.nz

Macpac Serac 1000 $1099.99
Alpine bag with 800FP water-resistant HyperDRY goose down, Pertex Quantum shell with DWR, bluesign certified, sliders for ventilation and climbing tie in, vertical and horizontal box baffles, secondary hand zips, mattress straps, fitted hood, anti-snag half zip. Temp rating -10°C (comfort), -17°C (limit), -40°C (extreme) Fill weight 1000g Weight 1469g. www.macpac.co.nz

Rab Neutrino Pro 700 $1099.95
Alpine bag with 800FP hydrophobic European goose down, recycled fabrics, water-resistant Pertex Quantum Pro shell, down-stabilising chevron-shaped baffles, close-fitting internal collar, three-quarter length YKK anti-snag zip, draft tube. Temp rating -4°C (comfort), -10°C (limit), -29°C (extreme) Fill weight 700g Weight 1140g. www.outfitters.net.nz

Therm-a-Rest Parsec 20°F / -6°C $989.99 (reg)
800FP Nikwax hydrophobic goose down, recycled soft-touch nylon fabric, ergonomic toe box, mattress straps, anti-snag YKK zipper, zoned insulation, quilt and blanket to customise sleep system, zippered pocket. Temp rating 0°C (comfort), -6°C (limit), -23°C (extreme) Fill weight 470g Weight 805g. www.ampro.co.nz

Rab Mythic Ultra 180 $999.95
Heat-reflecting titanium coated lining, Pertex Quantum 7D shell, 900FP hydrophobic European goose down, trapezoidal baffles, proportionally assigned differential cut, 3D draft collar, draft tube, angled footbox. Temp rating 7°C (comfort), 0°C (limit), -12°C (extreme) Fill weight 180g Weight 400g. www.outfitters.net.nz

Big Agnes Pluton UL40 $949.99
850FP water-resistant DownTek, minimalist hood with drawcord, full-length two-way locking zipper, ergonomic footbox, interior loops for attaching liner, Pertex Quantum ripstop shell and lining. Temp rating 4°C (comfort) Fill weight 227g Weight 454g. www.gearshop.co.nz

Big Agnes Torchlight UL -7 $899.99 (reg)
Expandable side panels, 850FP water-resistant DownTek, body-mapped baffle construction, jacket-style hood, insulated hood draft tube, vaulted footbox, zipper draft tube. Fill weight 482g Temp rating -2°C (comfort), -8°C (limit), -26°C (extreme) Weight 1020g. www.gearshop.co.nz

Exped Winterlite -15 $899.99 (med)
Cold weather bag with 800FP 90/10 goose down, water-repellent shell, large hood, 3D draft collar, oversized draft tube, two-way zips, differential cut prevents down compression, soft-touch lining, 3D trapezoidal footbox. Temp rating -8°C (comfort), -16°C (limit), -37°C (extreme) Fill weight 850g Weight 1380g. www.bivouac.co.nz

Marmot Helium -9°C $899
Water-resistant 800FP goose down, curved baffles, multi-baffle hood, snagless insulated draft tube, full-length two-way zipper, secondary ventilating zipper. Temp rating -5.2°C (comfort), -12°C (limit), -31.3°C (extreme) Fill weight 623g Weight 935g. www.marmotnz.co.nz

Therm-a-Rest Hyperion 20°F / -6°C $829.99 (reg)
900FP Nikwax hydrophobic goose down, zoned insulation (70% of down on top), box baffled construction, mattress straps, ergonomic shape, long zipper, drawcord hood. Temp rating 0°C (comfort), -6°C (limit), -23°C (extreme) Fill weight 360g Weight 567g. www.ampro.co.nz

Marmot Hydrogen 30 -1°C $799
Water-resistant 800FP goose down, curved baffles, multi-baffle hood, snagless insulated draft tube, full-length two-way zipper, secondary ventilating zipper. Temp rating 0.9°C (comfort), -4.8°C (limit), -21.9°C (extreme) Fill weight 309g Weight 665g. www.marmotnz.co.nz

Macpac Azure 700 $749.99
Relaxed mummy shape, 700FP water-resistant HyperDRY duck down, recycled bluesign certified shell and lining fabrics, zip to another bag, side ventilation zips, box baffles, mattress straps. Temp rating -4°C (comfort), -11°C (limit), -30°C (extreme) Fill weight 700g Weight 1345g. www.macpac.co.nz

Rab Alpine 600 $699.95
Water-resistant Pertex Quantum Pro shell, recycled nylon lining, 650FP hydrophobic duck down, internal stash pocket, angled footbox, three-quarter-length side zip, internal collar, trapezoidal baffle chamber design. Temp rating -5°C (comfort), -12°C (limit), -32°C (extreme) Fill weight 600g Weight 1050g. www.outfitters.net.nz

Rab Women’s Ascent 500 $699.95
650FP hydrophobic European duck down, Pertex Quantum fabric, recycled 20D nylon lining, wide mummy shape, proportionally assigned differential cut. Temp rating 1°C (comfort), -5°C (limit), -22°C (extreme) Fill weight 500g Weight 1025g. www.outfitters.net.nz

Macpac Azure 500 $699.99
Relaxed mummy shape, 700FP water-resistant HyperDRY duck down, recycled bluesign certified shell and lining fabrics, zip to another bag, side ventilation zips, box baffles, concealed drawcords, mattress straps. Temp rating 0°C (comfort), -6°C (limit), -23°C (extreme) Fill weight 500g Weight 1097g. www.macpac.co.nz

Big Agnes Sidewinder SL20 -6°C $649.99
Designed for side sleepers, 650FP water-resistant DownTek, body-mapped insulation, jacket-style hood, pillow pocket, anatomic footbox, insulated draft tube, anti-snag full length zipper. Temp rating -1°C (comfort), -7°C (limit), -14°C (extreme) Fill weight 538g Weight 1020g. www.gearshop.co.nz

Sea to Summit Flame Fm II from $649.99
Women’s specific technical bag, wider at the hips and narrower at the shoulder, 850FP water-resistant goose down, zoned insulation, contoured mummy shape, half zip with two sliders, draft tube, hood draft collar. Temp rating 2°C (comfort), -4°C (limit), -18°C (extreme) Fill weight 310g Weight 490g. www.southernapproach.co.nz

The North Face Blue Kazoo $600
Mummy-shaped with water-resistant 700FP ProDown, 20D nylon shell, 20D nylon taffeta lining, anti-compression pads, fitted hood, vaulted footbox, zipper baffle, draft collar, sleeping pad loops. Temp rating -3°C (comfort), -9°C (limit), -28°C (extreme) Fill weight Not available Weight 1050g. www.thenorthface.co.nz

Exped Lite -5 $599.99 (med)
800FP 90/10 goose down, heat-retention comfort hood, 3D draft collar, differential cut prevents down compression, 3D footbox, soft-touch lining, 20D ripstop nylon shell, left or right side zip, mattress straps. Temp rating -2°C (comfort), -8°C (limit), -27°C (extreme) Fill weight 540g Weight 990g. www.bivouac.co.nz

Marmot Sawtooth -9°C $599
Cold-weather bag with 650-fill power water-resistant duck down, wrap-around footbox, stretch tricot baffles, multi-baffle hood, full-length two-way zipper with draft tube, ventilating secondary zipper. Temp rating -6°C (comfort), -13°C (limit), -33°C (extreme) Fill weight 655g Weight 1130g. www.marmotnz.co.nz

Big Agnes Spike Lake -9° $549.99 (reg)
600FP water-resistant DownTek down, baffle construction, mattress sleeve, contoured hood, ripstop nylon shell with DWR, nylon taffeta lining, two-way zipper, left or right zipper, draft-proof collar and zip. Temp rating -3°C (comfort), -10°C (limit) Fill weight 609g Weight 1190g. www.gearshop.co.nz

Therm-a-Rest Questar 32°F / 0°C $549.99 (reg)
650FP Nikwax hydrophobic goose down, zoned insulation, draft collar, full-length zipper draft tube, snag-free zipper, hood drawcord, external zip pocket, mattress straps. Temp rating 5°C (comfort), 0°C (limit), -15°C (extreme) Fill weight 400g Weight 850g. www.ampro.co.nz

Enlightened Equipment Revelation Quilt 20°F / -6°C $529.95 (reg)
850FP down, 10D nylon shell, quarter length zip and drawcords close the footbox, U-shaped continuous baffles, snap and drawcord neck closure, mattress straps. Temp rating -1°C (comfort), -6°C (limit) Fill weight 456g Weight 640g. www.packgeargo.co.nz

Macpac Escapade 500 $479.99
600FP duck down, Pertex Quantum shell with DWR, trapezoid baffles with interlocking compartments, full length zip, foot zip, neck collar with adjustable bungee, draft tube, dome closures. Temp rating -1°C (comfort), -7°C (limit), -25°C (extreme) Fill weight 500g Weight 1111g. www.macpac.co.nz

Therm-a-Rest Space Cowboy 45°F / 7°C $479.99 (reg)
Synthetic hollow-fibre eraLoft water-resistant insulation, zoned insulation, ThermaCapture lining traps radiant body heat, recycled nylon fabric, 3/4-length anti-snag zip, mattress straps, hood drawcord. Temp rating 11°C (comfort), 7°C (limit), -6°C (extreme) Fill weight 650g Weight 780g. www.ampro.co.nz

Sierra Designs Get Down 20 $329 (reg)
550FP bag with PFC-free DriDown, 20D polyester ripstop shell, soft-touch polyester taffeta lining, half-length anti-snag zipper, hood cinches tight, hand pocket. Temp rating -1.6°C (comfort), -8.3°C (limit) Fill weight 510g Weight 930g. www.furtherfaster.co.nz

Sierra Designs Cloud 35 from $429
Zipperless design, oversized integrated comforter, insulated shoulder pocket, self-sealing foot vent, sleeping pad sleeve, PFC-Free 800FP DriDown insulation, 15D nylon fabrics. Temp rating -2°C (comfort), -3°C (limit) Fill weight 268g Weight 930g. www.furtherfaster.co.nz

Sierra Designs Nitro 35 Quilt $349
Oversized design for more coverage, 800FP PFC-free DriDown, 15D nylon ripstop fabric, hide-away hood, full-length insulated hand/arm pockets, hide-away hood. Temp rating 3°C (comfort), -3°C (limit) Fill weight 289g Weight 567g. www.furtherfaster.co.nz

Marmot Trestles 15 -9°C $199.95
SpiraFil LT high loft synthetic insulation, secondary ventilating zipper, anti-snag slider, 3D footbox, full length locking YKK two way zipper, 3D hood, snagless insulated draft tube. Temp rating -2.6°C (comfort), -8.9°C (limit), -27°C (extreme) Fill weight 1018g Weight 1535g. www.marmotnz.co.nz

Marmot Women’s Trestles 30 -1°C $189.95
SpiraFil LT high loft synthetic insulation, 3D hood and footbox, fold-down secondary ventilating zipper, full length locking YKK two way zipper, 3D hood, snagless insulated draft tube. Temp rating -2.6°C (comfort), -7.7°C (limit), -25°C (extreme) Fill weight 600g Weight 1580g. www.marmotnz.co.nz

Sleeping bag liners

Increase the warmth of your bag and keep it cleaner for longer by using a sleeping bag liner.

Cocoon Silk Mummyliner $169.99
Adds up to 5.3°C of warmth, use as a standalone bag on warmer nights, drawstring hood, boxed foot-end and double stitching, machine washable. 125g. www.ampro.co.nz

Sea to Summit Reactor Liner Thermolite $99.99
Adds up to 8°C of warmth, use alone as a warm-weather bag, box foot, drawcord hood, machine washable. 248g. www.southernapproach.co.nz

Rab Thermic Neutrino Liner $69.95
Adds warmth, comfort and cleanliness. Polyester microfleece fabric, machine washable. 400g. www.outfitters.net.nz