Aim for about 10 percent of your body weight. For a 150-pound adult that is 15 pounds, which is convenient because 15 pounds is the size almost every brand actually stocks. It is less convenient if you are heavier: the CDC puts the mean weight of American men at 199 pounds and women at 171.8 pounds, so the standard blanket is under-weight for most adults in the country and you will need to go looking for 20 or 25 pounds. Round down rather than up if you are between sizes, and never put a weighted blanket on an infant or a toddler.
If you’re drenched most nights, or it started suddenly, that’s worth raising with a doctor — it’s outside what bedding can fix, and outside what we cover.
This page exists because the 10 percent rule gets repeated everywhere and almost never sourced, and because the arithmetic has a consequence nobody mentions. We also care about it for a reason specific to this site: weight and heat are directly connected, so getting the weight wrong is also a way of making yourself hot.
Where the 10 percent rule comes from
It is not a standard and no regulator sets it. It comes from the weights that clinical and research use settled on, and the trials are specific enough to be useful.
The most-cited study is a Swedish randomised controlled trial of weighted chain blankets for insomnia in people with psychiatric disorders, reported by the American Academy of Sleep Medicine. It enrolled 120 adults with an average age of 40. Participants in the weighted blanket group “tried an 8-kilogram (about 17.6 pounds) chain blanket at the clinic. Ten participants found it to be too heavy and received a 6-kilogram (about 13.2 pounds) blanket instead.” After four weeks, participants using the weighted blanket “were almost 26 times more likely to experience a decrease of 50 percent or more in their insomnia severity compared with the control group, and they were nearly 20 times more likely to achieve remission of their insomnia.”
Two things in that are worth pulling out. First, the working weights were 13 to 18 pounds for an adult population — which is where the familiar 15-pound blanket sits and roughly where 10 percent of body weight lands for a lot of people. Second, one in twelve participants found the first blanket too heavy and had to be stepped down. That is the single most practical finding on this page: too heavy is a real and common outcome, and the correction is to go lighter.
We should be straight about the limits too. That trial was in a psychiatric outpatient population, not in general hot sleepers, and it measured insomnia severity rather than temperature. It tells you what weights people tolerate and benefit from. It does not tell you that a weighted blanket will help you sleep, and it says nothing at all about whether you will be too warm under one.
The arithmetic nobody does
Here is the problem with buying by the rule. Take 10 percent of your body weight, then look at what is actually for sale.
Both weighted blankets in our own registry are 15 pounds. That is not a coincidence or a gap in our research — 15 pounds is overwhelmingly the size the category stocks, in part because it suits the widest band of buyers and in part because it keeps shipping costs sane. Fifteen pounds is 10 percent of 150.
Now the measured US figures, from the CDC’s anthropometric reference data for August 2021 to August 2023: mean weight for adults aged 20 and over is 199.0 pounds for men and 171.8 pounds for women. Ten percent of those is roughly 20 and 17 pounds. So the default blanket on the shelf is under-weight for the average American woman and substantially under-weight for the average American man.
That matters less than it sounds for comfort and more than it sounds for buying. A blanket a few pounds light still works — you simply get less of the effect you are buying. The mistake is the other direction: people who find 15 pounds underwhelming assume the product does not work for them, when the honest reading is that they bought two sizes down.
Ten percent of body weight, against the weights the category actually sells. Reference arithmetic, not a medical recommendation.| Your weight | 10 percent | Nearest common size | Note |
|---|
| 100-120 lb | 10-12 lb | 10 or 12 lb | Buy the dedicated light size, not a 15 |
| 130-150 lb | 13-15 lb | 15 lb | The size everyone stocks fits you |
| 160-190 lb | 16-19 lb | 15 or 20 lb | Round down to 15 if you are unsure |
| 200-250 lb | 20-25 lb | 20 or 25 lb | You will have to shop for it specifically |
| Over 250 lb | 25 lb and up | 25 or 30 lb | Check the blanket size as well as the weight |
Weight is not the only number that matters
Two more decisions change the result as much as the pounds do, and both are routinely ignored.
Coverage area. A 15-pound blanket cut at 48 by 72 inches and a 15-pound blanket cut at 60 by 80 inches do not feel the same, because the same mass is spread over different areas. Pressure is what you are buying, and pressure is weight per unit area. The practical rule is to size a weighted blanket to your body, not to the mattress — it should cover you and not hang over the sides, because the part draped over the edge of the bed is weight pulling the rest of it off you.
Fill material. Glass beads are denser than plastic poly pellets, so a glass-bead blanket reaches a given weight with less bulk, and less bulk is less insulation. That is the single most important choice for a hot sleeper under a weighted blanket, and it is the spine of our weighted blankets and heat guide.
Why going too heavy makes you hot
This is the part most weight guides leave out, and on a cooling site it is the point.
Pressure is the mechanism of a weighted blanket, and pressure is also what closes the gaps in bedding. A heavier blanket presses the layers beneath it flat against you, which compresses out the air spaces that were doing the insulating — and air spaces are also the route sweat vapour takes to leave. So weight does two things at once: it reduces loft, which is good, and it seals the surface, which is bad. The net effect is almost always warmer.
It also pins you. Part of how anyone stays comfortable overnight is small adjustments — a leg out, an arm free, a shoulder uncovered. A blanket at the top of your tolerated range makes those harder, so you get less of the self-regulation that was quietly keeping you in range. People describe this as the blanket being hot. Mechanically it is the blanket stopping you venting.
Which is why, on temperature grounds alone, round down. If you are 175 pounds and choosing between 15 and 20, take the 15. You lose a little of the sensation and you keep the ability to move.
The one firm line: children
Everything above is about adults. For infants there is nothing to weigh up. The American Academy of Pediatrics is unambiguous in its safe sleep guidance: “Don’t use weighted blankets, sleepers, swaddles or other weighted objects on or near your baby,” and it includes blankets, quilts, comforters, mattress toppers and pillows in the soft objects and loose bedding that “can increase your baby’s risk of entrapment, suffocation or strangulation.” Its alternative for warmth is to “dress them in layers of clothing or use a wearable blanket.”
For older children, weighted blankets are used, including on clinical advice, and we are not the right source for the age and weight thresholds. Ask the clinician or occupational therapist who suggested it. The general principles that a child must be able to remove the blanket unaided and must never have it over their head are not something to work out from a product listing.
If what you actually want is the calming pressure without putting mass over your whole body, a weighted body pillow is a reasonable way in: it is 8 pounds rather than 15, it covers a fraction of the area, and you can push it away. It is also the version we would suggest trying first in a warm bedroom — the wider case for them is on cooling body pillows.
