Oxygen Absorber Calculator: How Many cc Per Bag?
Enter the container volume, food type, number of containers and a safety margin. The calculator estimates the air left inside, takes 21% of it as oxygen, adds your margin and gives the cc per container. A 1-gallon bag of pasta or beans needs about 600 cc with the default 25% margin.
This calculator tells you how many cc of oxygen absorber each bag, jar or bucket needs. Enter the container volume, the type of food, how many containers you are filling and a safety margin. It estimates the air left inside, takes the 21% that is oxygen and converts it into absorber packets.
Air left inside: 0 ml · oxygen: 0 ml
Absorber per container: 0 cc · total: 0 cc
Using 300 cc: 0 · 500 cc: 0 · 2000 cc: 0 per container
Formula: cc = volume × air share × 0.21 (air is 21% oxygen) × (1 + margin). It is an estimate: always round up.
How does the calculation work?
Four steps: volume, share of air, 21% oxygen, then a margin.
- Air left inside = volume in ml × share of air. The share is 35% for dense food, 60% for medium and 80% for light.
- Oxygen = air × 0.21, because air is about 21% oxygen.
- Absorber per container = oxygen × (1 + margin), rounded up. The default margin is 25%.
- Packets = absorber per container ÷ packet size (300, 500 or 2,000 cc), rounded up. The total is cc per container × number of containers.
Example: a 3.8-liter gallon bag of beans leaves 3,800 × 0.6 = 2,280 ml of air. Oxygen: 2,280 × 0.21 ≈ 479 ml. With 25% margin, about 599 cc: two 300 cc or two 500 cc packets. The method follows Sorbent Systems, measuring volume of space.
How do I read the result?
Treat it as a minimum and round up to the packets you actually have. A packet rated 400 cc can take up about 400 ml of oxygen, and capacities add up.
| Your result per container | What it usually means | What to buy |
|---|---|---|
| Up to about 300 cc | Quart bags, jars or half gallons of dense food | One 300 cc absorber per container; most mylar bag kits include these |
| 300-600 cc | Gallon bags of rice, pasta or beans | 400-500 cc absorbers, or two 300 cc; see oxygen absorbers |
| 600-800 cc | Gallon bags of light or freeze-dried food | Two 400-500 cc absorbers; a kit with spare capacity helps |
| Over 1,500 cc | 5-gallon bucket liners | 2,000 cc absorbers, or several smaller ones |
If a kit includes fewer or smaller absorbers than your result, add a refill pack. Our ranking of the best mylar bags and oxygen absorbers shows how many each kit includes.
Which mistakes skew the result?
Picking a food type that is too dense, and leaving absorbers out while you pack.
- Wrong food type: pasta and beans leave far more air than rice. When in doubt, choose the lighter type.
- Half-full bags: a bag filled halfway holds more air than the calculator assumes for a full one. Enter a larger volume or pick a lighter type.
- Exposed absorbers: they start working as soon as their pack is opened. Use them within 15-30 minutes and reseal the rest.
For a ready-made chart by bag size, read how many oxygen absorbers do I need. For the whole packing process, see long-term food storage.
Frequently asked questions
How does the oxygen absorber calculator work?
It multiplies the container volume by the share of air your food leaves, then by 0.21, because air is 21% oxygen. It then adds your safety margin and rounds up to whole absorbers.
What volume should I enter for a 1-gallon mylar bag?
About 3.8 liters, the calculator’s default. Use 0.95 L for a quart, 1.9 L for a half gallon and about 18.9 L for a 5-gallon bag.
Which food type should I choose?
Dense for rice, sugar or flour (35% air), medium for pasta, beans or oats (60% air) and light for freeze-dried food or fruit chips (80% air). If unsure, pick the lighter option.
Why does the result differ from the 300-500 cc rule of thumb?
The rule of thumb covers typical gallon bags. The calculator adjusts for your food and margin, so light foods can need up to about 800 cc per gallon.
Is it a problem if I use more absorber than the calculator says?
No. Extra capacity does no harm to dry food. Too little is the real problem, so always round up.