Choosing a Compression Sack

Which size compression sack do I need for my sleeping bag?

ultra_sil_comp_sack_stuffed

Because sleeping bags vary in their packed volume (depending on whether they are down or synthetic, and as a result of different shell/liner fabrics), it’s not possible to simply equate a bag temperature rating with a compression sack size.

The best way to determine if your bag will fit in a specific compression sack is to measure its moderately compressed volume. Here’s how:

  • Put your bag in a cardboard box (one which is larger than the bag)
  • Measure the length and width of the box in inches
  • Press the sleeping bag down firmly until the upper surface is roughly level in the box
  • Measure the average depth that the bag occupies in inches
  • Now multiply length x width x depth = volume in cubic inches
  • Divide the total by 61 = volume in liters

You’ll find the volume of our compression sacks in liters on the Sea to Summit website.

Which compression sack should I choose?

If you need compression and waterproof protection and weight is not critical, we’d suggest the eVent Compression Dry Sack.  The eVent Compression Sack – Size M compresses from 14 down to 4.5 liters; weight is 5.2 ounces.

If you need compression and waterproof protection, and weight is critical, we’d suggest the UltraSil Compression Dry Sack with eVent. UltraSil Compression Dry Sack with eVent – Size M compresses from 14 down to 4.5 liters; weight is 3.2 ounces.

If you need compression but not waterproof protection and weight is critical, we’d suggest the Ultra-Sil Compression Sack. Ultra-Sil Compression Sack – Size M compresses from 15 down to 5 liters; weight is 3 ounces.

One other thought about storage for sleeping bags and insulated jackets:

If you need waterproof protection but do not need maximum compression, we’d suggest the eVac Dry Sack. The eVac Dry Sack – Size 13 Liter weighs 2.4 ounces. Note: When you pack your soft goods in the eVac sack, roll and click the roll-top closure then sit on the bag to squeeze out air through the eVent fabric base. Roll the roll-top closure down tighter and you’ve achieved a reasonable degree of compression. You’ll need to pack the bag into your backpack and pack other gear on top to prevent it drawing air back into the eVac sack.