Oxygen absorbers and Mylar bags work as a system
A Mylar (foil-laminate) bag provides the oxygen barrier; the oxygen absorber removes the oxygen left in the air sealed inside it. Neither works well alone. An absorber in a bag that leaks or lets oxygen through will keep absorbing until it is exhausted, and a barrier bag without an absorber still holds the oxygen that was in the air when it was sealed.
Air is about 21% oxygen. OxySorb™ sachets are rated by the volume of oxygen they are intended to absorb (cc), not by the size of bag they fit. The rest of the air, mainly nitrogen, stays in the bag, so a sealed bag usually looks slightly shrunken rather than vacuum-packed.
How many cc for my Mylar bag?
We use the same conservative starting rule as our oxygen absorber size guide: allow about 250cc of absorber capacity per litre of sealed bag volume. This treats the bag as if it were full of air and adds a margin above the roughly 210cc of oxygen in a litre of air. Filled bags often need less, but loose or bulky foods such as pasta, beans or dried fruit trap more air between pieces.
| Sealed bag volume | Conservative starting capacity | Example OxySorb choice |
|---|---|---|
| Up to 400 mL | 100cc | 1 × 100cc |
| Up to 800 mL | 200cc | 1 × 200cc |
| Up to 1.2 litres | 300cc | 1 × 300cc |
| Up to 2 litres | 500cc | 1 × 500cc |
| Up to 4 litres | 1000cc | 1 × 1000cc |
| Up to 8 litres | 2000cc | 1 × 2000cc |
| Up to 10 litres | 2500cc | 1 × 2000cc + 1 × 500cc |
| Up to 20 litres | 5000cc | 2 × 2000cc + 1 × 1000cc |
Bag sizes are sold by flat dimensions, and the volume a bag holds when filled varies with its shape and gusset. If the bag's capacity in litres is not stated, measure it: fill a sample bag with water or a dry ingredient of known volume to the seal line. Several sachets can be combined to reach the total capacity; spread them through a large bag rather than leaving them all at the top.
Packing Mylar bags step by step
- Use suitably dry food. Oxygen absorbers do not remove moisture and do not make moist food safe.
- Fill and label all the bags first, leaving enough clean bag above the food to make a flat, wrinkle-free heat seal.
- Open the absorber pack only when the bags are ready. Work promptly, add the sachets and seal each bag.
- Reseal unused sachets straight away in suitable oxygen-barrier packaging.
- Check the seals. Store the bags somewhere cool and dry, away from sunlight, and inside a rigid container if pests or punctures are a risk.
Safety notes
Sachets are single-use. Do not open, eat, microwave or try to reactivate them, and keep them away from children and pets. Removing oxygen does not destroy bacteria: moist and semi-dry foods such as jerky and bakery goods need a validated preservation process, not a general sizing table. This page is a starting guide, not a shelf-life guarantee.
Next steps
Compare all sizes in the OxySorb oxygen absorber range, read the oxygen absorber FAQ, or contact us with your bag size and food type.