π« Bean Bag Filling Calculator
How much filling your bean bag actually needs, in cubic feet and liters.
Filling Needed (85% fill)
How to Use This Bean Bag Filling Calculator
Bean bag filling is sold by volume, so the only question is how many cubic feet your bag needs. Pick the bag shape, enter the dimensions in inches, and the calculator returns the fill volume at the standard 85 percent fill level, in cubic feet and liters, plus how many standard refill bags to buy.
Choose round or square. Round covers classic round and pear-shaped bags; square covers cubes and loungers.
Measure the bag. For round bags, measure the diameter across the widest point. For square bags, measure length, width, and height.
Hit Calculate Filling. The headline number is the fill volume at 85 percent; details show liters and refill-bag count.
Buy slightly more than the result. Beads settle in the first weeks, so 10 percent extra covers the break-in top-up.
The Formula
The 85 percent rule is the key insight. A bean bag filled to 100 percent is a rigid ball; at 85 percent the beads have room to flow and mold around whoever sits down. Round bags use the sphere formula on the diameter, which slightly overstates pear-shaped bags, so treat the result as a generous estimate. Square bags use simple length-times-width-times-height.
Worked Example
A 36-inch round bean bag: radius 18 inches, so (4/3) x 3.1416 x 18^3 = 24,429 cubic inches of interior space, which is 14.1 cubic feet. At 85 percent fill: 14.1 x 0.85 = 12.0 cubic feet, or 340 liters. Standard refill bags hold 2 cubic feet each, so 12 / 2 = 6 bags exactly, and buying a seventh covers settling. Total cost at roughly $15 per bag: about $90 to $105 for a full fill.
Choosing the Right Filling
EPS beads are the default: cheap, light, and moldable, but they compress and need topping up yearly. Shredded memory foam costs more and weighs more, yet it holds shape for years and feels closer to a real chair. Microbeads are smoother and quieter but flatten fastest. For kids\' bags, EPS is fine because kids are light and the bags are small. For an adult lounger you will use daily, shredded foam is worth the premium. Whatever you choose, buy by volume: a "10-pound bag of beads" means nothing without the cubic-foot rating.
Filling Tips That Save a Mess
EPS beads carry static and will stick to everything. Work outdoors or in a garage, wear long sleeves, and lightly mist your hands with water or rub a dryer sheet on the bag opening to kill static. Use a funnel or cut the corner off the refill bag and tape it to the bean bag opening. Fill slowly and sit-test halfway: it is easy to add more, miserable to remove excess. After filling, fluff the bag daily for a week while the beads settle, then top up once. That second small fill is what makes a new bean bag feel right.
Worked Example: The Kids' 30-Inch Bag
A 30-inch round bean bag for the kids' room: radius 15 inches. Volume = (4/3) x 3.1416 x 15^3 = 14,137 cubic inches, which is 8.18 cubic feet. At 85 percent fill: 8.18 x 0.85 = 6.95 cubic feet, about 197 liters. Standard 2-cubic-foot refill bags: 6.95 / 2 = 3.5, so buy 4 bags. At roughly $15 a bag, the fill costs $60, and the leftover half bag covers the first year's settling.
The adult lounger version, 48 inches across: radius 24, volume 33.5 cubic feet, 85 percent fill = 28.5 cubic feet = 15 refill bags = about $225 in beads. Size scales the cost fast, which is why measuring first beats buying bags blindly.
Topping Up: The Annual Ritual
EPS beads compress 20 to 30 percent in the first year as air works out of the fill, so every bean bag needs an annual top-up. Mark it on the calendar: unzip, pour in a bag or two, done. Shredded foam compresses far less, which is its quiet economic advantage despite the higher upfront price.
The pouring itself is the legendary mess. EPS beads carry static that sticks them to everything. Veteran tips: pour on a humid day or mist the air lightly, rub a dryer sheet on the bag's inner liner, cut a small corner of the refill bag instead of opening it fully, and pour slowly with a helper holding the liner open. Five minutes of prep saves an hour of chasing beads across the room with a vacuum.
Memory Foam vs. Beads: The Five-Year Cost
Shredded memory foam costs roughly twice as much upfront but needs no annual top-up and lasts years longer. Over five years, beads at $90 plus four $30 top-ups total $210; foam at $160 once totals $160. The foam wins on money and on feel, closer to a real chair. Beads win on initial price and on moldability for kids who like to burrow. Pick by who sits in it.
A Second Worked Example: The 48-Inch Lounger
A 48-inch round lounger is a big bag. Treat it as a flattened sphere about 48 inches across and 20 inches tall when filled. The volume of that shape runs roughly 14 cubic feet. Fill it to about 80 percent so it stays squashy, and you need around 11 cubic feet of fill. At typical EPS bead density, that is roughly 11 cubic feet of beads, usually sold in 3.5-cubic-foot bags, so buy 3 bags and keep the third half-sealed for top-ups.
Check against the small bag to calibrate. A 30-inch kids' bag holds about 4 cubic feet filled, needing roughly 3 cubic feet of beads, or one standard bag. The volume scales with the cube of the diameter, which is why the 48-inch bag needs nearly four times the fill of the 30-inch, not twice. When in doubt between bag sizes at the store, remember the cubic rule: a slightly bigger bag is a much bigger fill order.
Why Bags Need Topping Up: Beads Compress
Fresh EPS beads are mostly air, and months of sitting crush that air out. A bag filled to perfect squish in January sits noticeably flatter by June, having lost 10 to 20 percent of its loft. This is not the bag leaking; it is thousands of tiny beads permanently deforming under repeated weight. Heavier users compress faster, and the favorite family bag always goes flat first.
Plan on an annual top-up of about 1 cubic foot for a regularly used adult bag, less for kids' bags. Buy fill in the same bead size as the original: mixing 3mm virgin beads with 5mm recycled beads gives a lumpy sit. And never overfill to "get ahead" of compression; a bag stuffed to 100 percent feels like sitting on a drum and compresses unevenly, while one at 80 percent settles evenly and stays comfortable for years.
EPS Beads vs Memory Foam: The Feel Difference
EPS beads, the classic fill, flow like a liquid around you and spring back instantly. They are light, cheap, and loud, that distinctive rustle, and they compress over time as described above. Memory foam fill, usually shredded, molds to your shape and holds it for a few seconds, giving a sinking, cradled feel with no noise. It barely compresses over time but costs two to three times more and weighs significantly more.
The five-year math favors foam for daily-use bags despite the sticker price. Three EPS top-ups at $25 each plus the original $40 fill is $115 over five years, approaching the $130 to $150 cost of a foam fill that needs nothing. For a kids' bag that gets outgrown in two years, cheap EPS wins easily. Match the fill to the bag's expected life: short life, beads; daily driver for years, foam.
The Funnel Method: Filling Without the Mess
Beads carry static and go everywhere. The fix is a two-person funnel pour, not a hopeful dump. Cut the corner off the fill bag to make a 3-inch opening, have one person hold it inside the bean bag's liner opening, and pour slowly while the other person keeps the liner's mouth wrapped around the fill bag. A paper funnel or a cut-off bottle neck bridges gaps between mismatched openings.
Kill the static first: wipe the liner's inside with a dryer sheet and mist the air lightly with water from a spray bottle. Work in a small room with the door closed, because one escaped handful in a hallway becomes a week of finding beads. Pour in the bathtub if you are truly nervous; the smooth sides contain every escapee and cleanup is a rinse. Fifteen careful minutes beats an hour of bead hunting.
Frequently Asked Questions
How much filling does a bean bag need?
Most bean bags need 80 to 85 percent of their interior volume in filling. A 36-inch round bean bag holds about 14.1 cubic feet inside, so it needs roughly 12 cubic feet of beads, about 340 liters. Enter your bag dimensions above for the exact number.
How do you calculate bean bag filling?
Find the interior volume, then take 85 percent of it. For a round bag, use the sphere formula with the diameter. For a square bag, multiply length by width by height. Convert to cubic feet by dividing cubic inches by 1,728, then to liters by multiplying cubic feet by 28.3.
How many bags of filling for a 5 foot bean bag?
A 5-foot (60-inch) round bean bag has about 65 cubic feet of interior volume. At 85 percent fill that is roughly 55 cubic feet, or about 1,560 liters. With standard 2-cubic-foot refill bags, that is 28 bags, which is why most people buy bulk bead boxes for large bags.
Should I fill my bean bag 100 percent?
No. A 100 percent fill makes the bag hard and puts stress on the seams. The sweet spot is 80 to 85 percent, which leaves room for the beads to shift and mold around you. If your bag feels flat, add filling in small amounts until it feels supportive but still gives.
What is bean bag filling made of?
Most filling is expanded polystyrene (EPS) beads, tiny lightweight foam balls. Alternatives include shredded memory foam, which is heavier and holds shape longer, and natural options like buckwheat hulls. EPS is cheapest and most common; shredded foam feels more like real furniture.
How often should I refill a bean bag?
EPS beads compress with use, so most bean bags need a top-up every 12 to 18 months. If the bag looks deflated or you sink to the floor, add 10 to 20 percent of the original fill amount. Shredded foam lasts longer, often several years before needing attention.
How many liters is a cubic foot of bean bag filling?
One cubic foot equals 28.3 liters. Filling is often sold in liters outside the US, so this conversion matters when ordering. A 12-cubic-foot fill is about 340 liters. Always buy by volume, not weight, since bead density varies.
Why is my new bean bag flat after a week?
Fresh EPS beads settle and compress under body weight during the first week or two. This is normal. Most manufacturers suggest buying 10 to 15 percent extra filling and topping up after the break-in period. Fluff and rotate the bag daily during the first week to settle beads evenly.