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Published July 12, 2026. Prices and specs checked August 18, 2026.
Buy a weighted blanket that weighs roughly 10% of your body weight, and size it to your body rather than your mattress. That means about 15 pounds for a 150-pound sleeper. The rule comes from the Sleep Foundation’s weighted blanket sizing guidance. It settles most of the purchase before the glass vs plastic beads debate even starts. The rest is fill physics. What is inside the blanket decides how thick, how quiet, and how warm it feels at any given weight.
This guide works criteria-first. It starts with a size matrix, then teaches the four factors that decide satisfaction: weight, fill density, cover, and footprint. The matrix covers four named, currently sold blankets, using the makers’ own published spec pages.
Weighted blanket size matrix: glass vs plastic beads by body weight
I have slept under heavy quilts and handled weighted blankets of both fill types for years. The tag weight matters less than you would think. How the fill sits and how the cover handles heat decide whether a blanket stays on the bed.
| Your body weight | 10% target | Glass-bead options (published size) | Plastic-pellet option (published size) |
|---|---|---|---|
| ~100–130 lb | 10–13 lb | Gravity 10 lb (42 × 66 in) | Mosaic Twin 12 lb (42 × 72 in) |
| ~130–170 lb | 13–17 lb | Gravity 15 lb (48 × 72 in); YnM 15 lb (48 × 72 in, listed for a ~140 lb sleeper) | Mosaic Twin 15 lb (42 × 72 in) |
| ~170–220 lb | 17–22 lb | Gravity 20 lb (48 × 72 in); YnM 20 lb (48 × 72 in, listed for a ~190 lb sleeper) | Mosaic Twin 20 lb (42 × 72 in) |
| ~220 lb and up | 22–25 lb | Gravity 25 lb (48 × 72 in) | Not offered above 20 lb in Mosaic’s Twin line |
How the size matrix was built
The matrix applies the 10% rule to the published dimensions and weights of four named, currently sold blankets. They are the Gravity Weighted Blanket and YnM’s cotton weighted blanket, both glass bead. SensaCalm’s finished weighted blankets are glass bead too, formerly poly pellet. Mosaic’s solid cotton weighted blanket is filled with BPA-free polystyrene pellets, per Mosaic’s product page. All dimensions and weights come from the makers’ own spec pages and listings, checked August 2026.
Two things stand out in the makers’ numbers. First, the published pairings track the 10% rule closely. YnM’s own listing pairs its 15 lb blanket with a roughly 140 lb sleeper (15 ÷ 140 ≈ 10.7%). It pairs its 20 lb blanket with a roughly 190 lb sleeper (20 ÷ 190 ≈ 10.5%). Second, dimensions stay body-sized even as weight climbs. Gravity’s 25 lb blanket is still only 48 inches wide, a deliberate fit-the-body choice, not a cost cut.
Criterion 1: weight and the 10% rule
The Sleep Foundation’s sizing guidance states the rule plainly. A weighted blanket should weigh about 10% of your body weight. Preferred weights in practice range from 5% to 12% of the sleeper’s weight. The arithmetic is simple: 120 pounds × 0.10 = 12 pounds; 150 × 0.10 = 15; 200 × 0.10 = 20; 250 × 0.10 = 25. Manufacturers publish the same math. Mosaic Weighted Blankets, for example, recommends "approximately 10% of your body weight" on its own product pages.
Treat the rule as a starting point, not a prescription. Some sleepers prefer the lighter end of that 5–12% band. The Sleep Foundation cautions that a blanket that is too heavy can restrict airflow and make breathing harder. It specifically advises people with low blood pressure, respiratory disorders, type 2 diabetes, or obstructive sleep apnea to talk to a doctor before using one. When in doubt, err lighter.
Criterion 2: fill density and what glass vs plastic beads changes
Fill material is a density question. Glass microbeads are heavier per unit of volume than plastic poly pellets. So a glass-filled blanket reaches its target weight with a thinner, smoother layer of fill. SensaCalm, a maker that switched from polypropylene pellets to glass, explains it on its own FAQ page. Glass is heavier per square inch than poly pellets, so less raw material is needed to reach the same weight. The practical consequences follow directly from that physics.
- Thickness and drape: A glass-bead blanket lies flatter and drapes more like normal bedding. A pellet blanket of the same weight is bulkier and more textured.
- Noise: Fine, sand-like glass beads tend to rustle less than larger pellets when you shift.
- Heat: The thinner glass-fill layer traps less air, so it tends to sleep cooler. The cover fabric does much of the temperature work either way.
- Construction: Whichever fill you choose, small quilted pockets matter more than the bead material. They keep the fill from migrating, which preserves even pressure. Gravity, for instance, describes its glass beads as held in gridded pockets to prevent migration.
Neither fill is wrong. Pellets remain the budget-friendly route into weighted bedding, and some sleepers prefer their chunkier, more tactile feel. Glass is the premium default for a sleeker, quieter, cooler blanket.
Criterion 3: cover fabric and washability
A removable, machine-washable cover is the difference between easy upkeep and a laundry problem. The weighted inner usually needs gentler care. Gravity’s spec page is typical. The outer cover is removable and machine washable in cold water, while the weighted inner is hand-wash and air-dry only. If you run hot, a breathable cotton shell or a dedicated cooling cover matters as much as the fill choice. Always follow the care label on the specific blanket you buy.
Criterion 4: size to the body, not the bed
A weighted blanket is meant to rest on the sleeper, not drape over the mattress edges. SensaCalm puts it bluntly in its FAQ: weighted blankets are made to fit the body, not the bed. That is why so many are sold in narrow 42–48 inch widths. It also means couples are usually happier with two individual blankets than one shared queen- or king-size. A shared blanket drags toward whoever moves, and per the 10% rule, two people rarely need the same weight anyway.
Scoring glass vs plastic beads blankets against the criteria
| Criterion | Gravity (glass) | YnM (glass) | SensaCalm (glass) | Mosaic (pellets) |
|---|---|---|---|---|
| Weight range for the 10% rule | 10–25 lb, four steps | 15–20 lb common sizes | Weight suggested per size on its site | 5–20 lb across sizes |
| Fill feel | Fine beads, gridded pockets | Fine beads, small compartments | Fine beads sewn into squares | Chunkier pellet texture |
| Cover washability | Removable, machine-washable cover; inner hand-wash | Follow care label | Follow care label | Follow care label |
| Body-size vs bed-size | Body-sized (42–48 in wide); a 35 lb 90 × 90 in bed size is also listed | Body-sized twin; bed sizes exist | Explicitly body-fit sizing | Body and bed sizes up to King |
The pattern across the market is clear enough to name a direction. Glass beads have become the standard. Even SensaCalm, a longtime pellet maker, moved to glass. Pellet fills like Mosaic’s survive mainly where a chunkier texture or a lower price matters more than sleekness. If you want the thin, quiet, cooler-sleeping version of any given weight, glass is the pick. If you want the most tactile pressure per dollar, pellets still earn their place.
How glass vs plastic beads blankets were compared
Every number here comes from a published source named in the sentence where it appears. The Sleep Foundation’s weighted blanket weight guidance supplies the 10% rule, the 5–12% range, the child minimums, and the medical cautions. For the infant warning, the CPSC’s April 2024 commissioner statement and the AAP positions it cites are the sources. Dimensions, weights, fills, and care instructions come from the manufacturers’ own spec pages and listings (Gravity, YnM, SensaCalm, Mosaic), all checked live in August 2026. Gravity’s and Mosaic’s pages were read again on October 10, 2026.
The comparison is built from published specifications and owner-facing documentation. It avoids exact temperature or decibel claims no maker publishes. Read more about how we work in our editorial standards. If you are also rethinking the layer on top, our comparison of down, down-alternative, and wool comforters pairs naturally with this decision.
Glass vs plastic beads weighted blanket FAQs
How heavy should a weighted blanket be?
About 10% of your body weight, per the Sleep Foundation’s guidance. That is roughly 15 pounds for a 150-pound sleeper. Preferred weights range from 5% to 12% in practice. Comfort and any health considerations override the formula, and lighter is the safer direction when unsure.
Are weighted blankets safe for babies or toddlers?
No. The CPSC warned in April 2024 against weighted blankets and swaddles for infants, citing AAP guidance that weighted sleep products can lower a baby’s oxygen levels. Sleep Foundation guidance describes weighted blankets as generally appropriate only for children at least 3 years old and 50 pounds, with a physician consulted first.
How do glass vs plastic beads differ in a weighted blanket?
Density. Glass beads are heavier for their size, so the blanket hits its target weight with a thinner, smoother, usually quieter and cooler layer of fill. Plastic poly pellets need more volume for the same weight. That makes the blanket bulkier and more textured, a feel some sleepers prefer, often at a lower price.
Can two people share one weighted blanket?
Two separate blankets usually work better. A weighted blanket is sized to the body, not the bed. A shared one drags toward whoever moves, and the 10% rule rarely lands two partners on the same weight anyway.
Takeaway on glass vs plastic beads and the 10% rule
Run the arithmetic first: body weight × 0.10. Then round to the nearest offered weight and size the blanket to your body, not your mattress. Choose glass beads for a sleeker, quieter, cooler blanket. Choose plastic pellets for a chunkier feel at a friendlier price. Insist on a removable, machine-washable cover either way. Nail the weight and the cover, and either fill delivers the grounding pressure you came for. For more bedding comparisons, visit our Home & Living section.
