How to Buy a Kotatsu in the US: 120V Models, the Right Futon Size, and How to Use It Safely

In Japanese homes, winter means the kotatsu (炅燵): a low table with a small heater under it and a thick futon draped over the frame. You slide your legs underneath, the futon traps the heat, and suddenly nobody wants to leave the table. Kotatsu have become popular in the US through anime and travel, and you can buy them on Amazon. But there is a catch that most guides miss: some kotatsu sold in the US come with Japan's 100-volt heater. This guide explains how a kotatsu works, what to check before you order, and how to use one safely.

How a kotatsu works

The heater only warms the small space under the table, not the whole room, which is why a kotatsu feels so cozy with so little heat. In Japan the usual setup is the table, a kotatsu futon (a large quilted blanket made for the purpose), and a rug or mat underneath. In summer you take the futon off and use it as an ordinary low table.

Check these four things before you order

The voltage trap. Japan runs on 100 V; the US runs on 120 V. When we checked in October 2026, the AZUMAYA KT-109 listing described an AC 100 V, 510 W heater and said it might need a voltage converter, and a KEN JAPAN table sold as "US-KLY" listed an AC 100 V, 300 W heater with a note that a converter is required. We don't recommend running a heater through a converter. Buy a model whose description says 120 V for the heater itself.

Safety listings. In the US, heaters tested by a recognized lab carry a mark such as UL or ETL. None of the kotatsu listings we checked mentioned one, so ask the seller before you buy, and treat the kotatsu like any space heater.

Three 120 V kotatsu tables

The drawings below are simple illustrations, not product photos. Prices and stock on Amazon change often, so check each listing.

KEN JAPAN KB-75US: a simple square table. The listing says its heater is compatible with 120 VAC and warms up in about 10 to 15 seconds after you switch it on. The 29.5-inch square top is reversible, and the seller says it seats up to four people. No futon is included.

BJDesign Kotatsu Table: quartz heater, three colors. BJDesign lists an AC 120 V quartz tube heater with a temperature control knob and an on/off switch, in a 29-inch square table in natural, black or white wood grain.

PaletteLife Kotatsu: a fan to spread the heat. PaletteLife says its heater has a built-in fan that circulates warm air under the table, an adjustable temperature knob and a heat-resistant safety fuse cover, and works with standard North American 120 V outlets. The table is a 31-inch square.

The kotatsu futon

The futon is what makes a kotatsu work, so don't skimp. It needs to be big enough to reach the floor on every side: for a 29 to 31 inch square table, look for a square kotatsu futon of about 75 to 81 inches. IKEHIKO, which the listing describes as a Japanese interior maker with a 130-year history, says its futons are made by futon craftsmen in Japan from Japanese materials. FULI sells a cotton *shijira* kotatsu blanket in an 81-inch square.

Using a kotatsu safely

• Don't sleep in it. It is tempting, but Japanese manufacturers warn not to use a kotatsu as a sleeping heater: hours of gentle heat can cause low-temperature burns and dehydration.
• Keep the futon and clothes off the heater. Don't dry laundry or stuff cushions under the table.
• Plug it straight into a wall outlet, not an extension cord or power strip, and don't pinch or bend the cord under the table legs.
• Turn it off when you leave the room, and keep an eye on children and pets, who like to crawl inside.
• Put a rug underneath to keep heat in and protect the floor.

Which one suits you?

• A simple, compact table for two to four: KEN JAPAN KB-75US.
• A quartz heater and a choice of colors: BJDesign.
• Heat spread more evenly by a fan: PaletteLife.
• Whichever table you pick: add a square kotatsu futon of 75 to 81 inches and a rug, and confirm the heater says 120 V.
• Want the rest of a Japanese home too? See How to Get a Japanese Toilet at Home.