Bean Bag Filling Calculator: How Many Litres or Cubic Feet of Beads You Need

How it works

Cover volume: classic (egg shape) = π ÷ 6 × W × D × H · round = π ÷ 6 × D³ · box = W × D × H · cylinder = π ÷ 4 × D² × H · Beads = cover volume × fill % · Bags = beads ÷ bag size, rounded up · 1 cu ft = 1,728 cu in = 28.32 L · 1 L = 1,000 cm³

The calculator first works out the volume the empty cover would hold if it were packed solid. A classic pear or slouch bean bag is closest to an egg shape (an ellipsoid) that fits inside its width, depth and height, which holds π ÷ 6, or about 52%, of the box around it. A round bean bag is a sphere, a cube or footstool is a box, and a bolster is a cylinder. You never fill a bean bag to the top: the beads need room to move so the seat shapes itself around you. Around two-thirds full is the usual comfortable fill, 60% feels soft and 80% feels firm and supportive. The bead volume is the cover volume times that fill level, and the number of bags is the bead volume divided by the size of one bag, rounded up. The table shows how the amount changes from 50% to 100%. The result is an estimate. Covers stretch, measured sizes are rarely exact and beads compress over time, so a little left over for topping up is useful. It applies to loose EPS (polystyrene) beads; shredded foam packs differently and is usually sold by weight. Unlike a pillow insert calculator, which sizes a cushion to its cover, this one gives the volume of loose filling.

Worked example

A classic bean bag measuring 80 × 80 × 110 cm (31.5 × 31.5 × 43.3 in) has a cover volume of π ÷ 6 × 80 × 80 × 110 = 368,614 cm³ = 368.6 L (13.0 cu ft). At a medium 70% fill it needs 368.6 × 0.70 = 258 L (9.1 cu ft) of beads, which is 3 bags of 100 L with about 42 L left over. At a firm 80% fill it needs 295 L, still 3 bags. With the default inputs on this page (32 × 32 × 44 in, 70%, 3 cu ft bags), the cover holds 23,591 cu in = 13.65 cu ft, so you need 13.65 × 0.70 = 9.56 cu ft (271 L) of beads: 9.56 ÷ 3 = 3.19, so buy 4 bags of 3 cu ft.

Sources: Calculate.co.nz: Bean bag filling calculator (ellipsoid cover, 80 × 80 × 110 cm example) · Bean Products: Fill calculators (bean bag chairs start at about 40% of the measured volume)

Frequently asked questions