How Many Oxygen Absorbers Do You Need Per Bag Size? (Free Calculator)

A full 1-gallon Mylar bag usually needs 300cc to 500cc of oxygen-absorbing capacity. A full 5-gallon bag usually needs 2,000cc to 2,500cc. Use the lower end for tightly packed foods like rice or wheat, and the higher end for foods that trap more air, like pasta, rolled oats, or freeze-dried produce.

Below, you’ll find a complete oxygen absorber size chart, simple packet-count calculations, and packing tips. At the end, Wallaby’s free food calculator can help you plan how much food your household needs before you start filling bags.

Oxygen Absorber Size Chart by Bag Size

Use this oxygen absorber size chart as a practical starting point for properly dried, shelf-stable food. “Dense food” includes items such as white rice, wheat berries, flour, and fine grains. 

Bulky food includes pasta, large beans, rolled oats, dehydrated vegetables, and freeze-dried pieces because these foods hold more air between and inside the pieces.

What Does “cc” Mean?

The “cc” printed on an oxygen absorber tells you how many cubic centimeters of oxygen the packet can absorb. A 500cc packet is designed to absorb 500 cubic centimeters of oxygen, not 500 cubic centimeters of air.

Normal air contains about 21% oxygen. The rest is mostly nitrogen. That is why a correctly packed Mylar bag may tighten slightly without becoming as flat as a vacuum-sealed bag.

The packet count is less important than the total cc capacity. For example:

• One 500cc packet provides 500cc of total capacity.
• Two 300cc packets provide 600cc of total capacity.
• Five 500cc packets provide 2,500cc of total capacity.
  

Multiple smaller packets can reach the same total capacity as one larger packet. They can also be spaced through a deep container, though one correctly sized packet is simpler for most 1-gallon bags.

Why Food Type Changes Sizing

Two bags of the same size can need different oxygen absorber sizes. The difference is residual air, which includes visible headspace above the food and small air pockets between food particles.

Dense foods settle closely together and leave less residual air. Loose or irregular foods create larger gaps. As a result, a gallon of pasta may need more oxygen-absorbing capacity than a gallon of white rice.
Use these groups when reading the oxygen absorber size chart:

This helps the food settle and reduces large pockets of trapped air. Do not crush delicate freeze-dried foods just to save absorber capacity.

How to Calculate How Many Oxygen Absorbers Per Bag

For most home storage jobs, the chart above is the fastest option. If your bag is an unusual size or has extra headspace, use this simple oxygen absorber sizing calculation:

Required capacity in cc = bag volume in cc x estimated residual air fraction x 0.21 x 1.25

The 0.21 accounts for oxygen making up about 21% of air. The 1.25 adds a 25% sizing cushion for imperfect estimates. After calculating, round up to the next available packet size.

Use one of these estimated residual air fractions:

• 0.35 for dense food: fine grains, flour, rice, or tightly settled wheat
• 0.45 for medium-density food: beans, lentils, small pasta, or oats
• 0.55 for airy food: large pasta, freeze-dried produce, or loosely packed pieces
  

These are practical estimates, not laboratory measurements. The true amount changes with product shape, fill level, and how tightly the food settles. For a more exact calculation, residual air must include both the space above the food and the gaps inside the food mass.

Common Volume Conversions

• 1 pint = about 473cc
• 1 quart = about 946cc
• 1/2 gallon = about 1,893cc
• 1 gallon = about 3,785cc
• 5 gallons = about 18,927cc
  

Example: 1-Gallon Rice Bag

A 1-gallon bag has a volume of about 3,785cc. Rice is dense, so use a residual air fraction of 0.35.

3,785 x 0.35 x 0.21 x 1.25 = about 348cc

Round up to a 400cc or 500cc absorber. A 300cc absorber may work when the bag is packed very tightly with little headspace, but choosing 400cc to 500cc gives you more room for packing differences.

Example: 1-Gallon Pasta Bag

Pasta traps more air, so use a residual air fraction of 0.55.

3,785 x 0.55 x 0.21 x 1.25 = about 547cc

Use at least 600cc of total capacity if the bag is loosely filled, such as two 300cc packets. If you settle the pasta well and leave minimal headspace, one 500cc packet is a practical standard choice.

Example: 5-Gallon Wheat Bag

A 5-gallon bag holds about 18,927cc. Wheat packs densely, so use 0.35.

18,927 x 0.35 x 0.21 x 1.25 = about 1,739cc

Round up to one 2,000cc absorber. For a looser food or a bag with more headspace, move up to 2,500cc.

Simple calculator worksheet

1. Select the bag’s filled capacity in gallons.
2. Multiply gallons by 3,785 to convert the volume to cc.
3. Multiply by 0.35, 0.50, or 0.60 based on food density.
4. Multiply by 0.21 for the oxygen portion of the trapped air.
5. Multiply by 1.25 for a sizing buffer.
6. Round up to the next available absorber size.
   

This method is still an estimate. If you know the actual residual air volume, use it instead: residual air volume x 0.21 = minimum oxygen capacity. Do not subtract food weight from container volume unless you know the food’s true bulk density, since one gram of every food does not occupy one milliliter.

Free Sizing Calculator by Wallaby Goods

Use it to estimate how much food to store, then apply the oxygen absorber size chart above to choose the cc capacity for each filled bag. Use Wallaby’s free emergency food storage calculator to estimate minimum supplies for two weeks through one year. 

Wallaby’s free Emergency Food Supply Calculator estimates the minimum grains, beans, meats, dairy, fats, sugar, fruits, vegetables, and water a household needs for 2 weeks to 1 year. 

It covers grains, beans, dairy, water, and other pantry essentials, helping you estimate how many bags you will fill before using this oxygen absorber size chart to plan the packets.

Important Note: It is a food-supply planning tool, not an oxygen absorber sizing calculator. Use it to plan your household’s quantities.

Oxygen Absorbers by Bag Size

1-Quart Bags

Use 100cc for tightly packed foods. Choose 200cc when the food is bulky, the bag is not full, or you want a modest safety margin.

Quart bags work well for foods you expect to open in smaller batches. They also reduce the amount of food exposed to air after opening.

1-Gallon Bags

Use 300cc for a tightly filled bag of dense food. Choose 400cc to 500cc for beans, oats, pasta, or freeze-dried foods that leave more void space. Wallaby Goods recommends roughly 400cc per gallon as a general rule, with 300cc for smaller needs and 500cc for extra protection.

A 1-gallon format is easy to handle and limits losses if one seal gets damaged. It also lets you rotate food without opening a large family-size supply.

2-Gallon Bags

Start around 600cc for dense foods and move toward 1,000cc for loose foods. You can combine packets to reach the target. For example, two 300cc packets provide 600cc, while two 500cc packets provide 1,000cc.

Avoid assuming that a single 500cc packet will cover every 2-gallon bag. It may be too small when the food is bulky, or the bag has generous headspace.

5-Gallon Bags

Use 2,000cc for dense staples and 2,500cc for foods that trap more air. This aligns with Wallaby Goods’ sizing range for large Mylar bags.

For physical protection, place a sealed 5-gallon Mylar bag inside a food-grade bucket. The Mylar layer provides the oxygen and moisture barrier, while the bucket helps guard against punctures, crushing, and pests. 

A plain plastic bucket can allow oxygen to pass through over time, so the Mylar liner matters for long-term storage.

How Many Packets Per Bag?

You can use any packet combination that meets or exceeds the target cc capacity. The math is simple:
Number of packets = target cc capacity divided by cc per packet, rounded up

When the division is uneven, always round up. Do not round down from 3.3 packets to three packets.

Using more than one packet does not multiply shelf life. It only increases total absorbing capacity. Once you meet the bag’s oxygen-removal requirement, a good heat seal and suitable storage conditions matter more than adding unnecessary packets.

Is Oversizing Safe?

For properly dried food in oxygen-barrier packaging, modest oversizing is generally preferable to undersizing. A 500cc packet in a 1-gallon bag of rice may have unused capacity, but it helps cover extra headspace, loose packing, and short exposure during sealing.

Oversizing cannot fix a leaking seal, damaged bag, or unsuitable food. If outside air continues entering the package, the absorber will eventually reach capacity. Use a clean, wrinkle-free heat seal and check the bag for pinholes before storage.

How to Pack Each Bag

1. Choose suitable food. Use dry, low-oil food that is appropriate for room-temperature storage.
   
   
2. Inspect the bag. Check the Mylar bag for holes, damaged seams, or a dirty sealing area.
   
   
3. Fill and settle it. Leave enough clean space at the top for a wide heat seal, then gently tap the bag to reduce air gaps.
   
   
4. Calculate the absorber size. Use the chart or calculator and round up when the answer falls between packet sizes.
   
   
5. Stage every bag first. Fill, label, and position all bags before opening the absorber package.
   
   
6. Add absorbers quickly. Place the required packet capacity inside each bag without opening the individual sachets.
   
   
7. Heat-seal the bag. Make a straight, complete seal across the full width. The zipper, if included, is for convenience after opening and does not replace the heat seal.
   
   
8. Inspect and label. Write the food, packing date, and absorber capacity on the bag.
   
   
9. Protect the package. Store sealed bags in a cool, dark, dry place, using a bucket or tote when puncture protection is needed. 

Fresh oxygen absorbers start reacting as soon as their outer package is opened. Guidance recommends using them within about 15 minutes and moving leftovers immediately into a small airtight glass jar or heat-sealed barrier pouch.

Pack the Right Amount With Wallaby Goods

Correct oxygen absorber sizing protects the time, food, and money invested in your emergency pantry. Start with 300cc to 500cc for a 1-gallon Mylar bag and 2,000cc to 2,500cc for a 5-gallon bag, then adjust for food density and headspace.

Wallaby Goods offers oxygen absorbers and Mylar food-storage solutions sized for small storage and bulk staples. Choose enough total cc for the bag, work quickly, create a full heat seal, and store each package somewhere cool, dark, and dry.