Mattresses, explained.

Every mattress sold in the United States has already passed a fire test with two published numbers, and no test at all for firmness. Under the federal open-flame standard at 16 CFR 1633.3(b), a mattress specimen has to hold its peak rate of heat release under 200 kilowatts at every point in a 30-minute burn and its total heat release under 15 megajoules across the first 10 minutes. Comfort has no equivalent: there is no federal definition of medium-firm, and the only numbers describing how a mattress holds you up are the ones the manufacturer chooses to publish. The condition that changes which figures apply is the foundation, because the flammability certification on the label is written for the mattress used alone, with a named foundation, or both.

The federal fire test is 200 kilowatts and 15 megajoules

The procedure behind those two limits is specified down to the gas flow. 16 CFR 1633.7 sets an ignition source of two T-shaped propane burners with a total heat release rate of 27 kilowatts, the top burner running for 70 seconds and the side burner for 50 seconds, with heat release measured by oxygen consumption calorimetry. Specimens are conditioned in air between 65 °F (18 °C) and 77 °F (25 °C) at under 55 percent relative humidity for at least 48 continuous hours before the burn.

The sampling rule matters as much as the thresholds. Under 16 CFR 1633.4(a), a manufacturer tests three specimens of each prototype and all three have to pass; if one fails, the prototype is not qualified. Records supporting a prototype are kept for as long as mattresses based on it are in production and for 3 years after that.

A cigarette test came first and still applies

The open-flame standard sits on top of an older one. The CPSC's mattress page describes 16 CFR Part 1632 as a test of ignition resistance when a mattress or mattress pad is exposed to a lighted cigarette, with a pass requiring that the product not create a char length more than 2 inches (5.1 cm) in any direction from the nearest point of the cigarette. That same CPSC page covers crib mattresses, futons, sleeper chairs and convertible sofa bed mattresses under the smoldering standard, and states the peak 200 kW and 15 MJ limits for the open-flame standard.

The white label carries the prototype number and the build date

16 CFR 1633.12 specifies a permanent, conspicuous, legible label measuring 2 3/4 inches wide, white with black text, carrying the manufacturer's name and complete physical address, the month and year of manufacture, the model identification, the prototype identification number, and a certification reading that the mattress meets the requirements of 16 CFR part 1633 when used without a foundation, with a named foundation, or both. The intended pairing is printed in 10-point uppercase type.

That label is the one document on a mattress with a date on it. It is also, under paragraph (e) of that section, the only label nobody except the final owner is permitted to remove.

CertiPUR-US certifies the foam, not the finished mattress

A second mark appears on foam mattresses and means something narrower. CertiPUR-US states that certified foam is made without formaldehyde, without ozone depleters, without phthalates regulated by the U.S. Consumer Product Safety Commission, and without mercury, lead and other heavy metals, is screened for relevant chemicals including flame retardants classified as carcinogens, mutagens or reproductive toxins, and has low volatile organic compound emissions for indoor air quality of less than 0.5 parts per million. The unit of that claim is the foam, so a certified foam layer inside a mattress says nothing about the cover, the adhesives or the coils. Emission figures behave the same way on an air purifier spec sheet, where the rating describes one component under one condition.

Example: what Saatva publishes about the Classic

As an example, Saatva's own specification page for the Saatva Classic lists two heights, 11.5 inches and 14.5 inches, a bottom support coil unit at 13 gauge, individually wrapped comfort coils at 14.5 gauge, and a stated limit of up to 300 pounds per sleeper. The coil counts by size are the manufacturer's:

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The arithmetic is worth doing before the showroom. Going from the queen's 1,300 coils to the king's 1,608 adds 308 coils, a 24 percent increase that arrives with a larger sleeping area, so a raw coil count compares sizes rather than support. The 300-pound-per-sleeper figure Saatva publishes is per person, which puts a shared queen at 600 pounds of occupants. Lower gauge means thicker wire, so the 13-gauge base coils are heavier wire than the 14.5-gauge comfort coils above them. None of those numbers is defined by a federal standard, which is why comparing them across two brands only works when both publish the same fields, the same problem that makes ergonomic office chairs and smart rings hard to line up side by side.

Before you buy a mattress

• The white law label: the month and year of manufacture, the prototype identification number, and which foundation the 16 CFR 1633 certification names.
• The coil count and coil gauge for your size, in writing, since gauge is only comparable when both brands state it.
• The foam density in pounds per cubic foot for each comfort layer, which the flammability standard does not require anyone to publish.
• Whether CertiPUR-US covers every foam layer or one of them, and the under-0.5-ppm VOC emissions figure behind that mark.
• The trial period in nights and the return cost: pickup fee, restocking fee, or original packaging requirement.
• The warranty's sag threshold in inches, which is the measurement a claim is judged against.