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How Does a Rice Cooker Know When the Rice is Done? 

By: Author Jeff Campbell

Posted on  - Last updated:

Categories Rice Cookers

People have been boiling rice for centuries. But lately, people have found a way to get fool-proof rice every time with a rice cooker. But how does a rice cooker know when the rice is done?

As a general rule, a rice cooker automatically shuts off when the internal temperature inside the cooker reaches the appropriate setpoint of 212° F. This happens by default when the correct amount of water gets absorbed into the rice.

But there’s a lot more to know about rice cookers, how long they take, and how they know when to stop cooking.

So in this article, we’re diving deep into rice cookers. We’ll even explore some other foods they work great for, and how to fix undercooked rice in a rice cooker. Let’s get going!

But first, let’s answer another question:  What is a rice cooker?

We have pressure cookers , slow cookers, microwaves, and the latest craze, the InstaPot. In between those, the rice cooker or sometimes referred to as a rice steamer came onto the market. This kitchen appliance automatically cooks rice to perfect consistency.

There is a cooking bowl, heat source, and thermostat that all work together to deliver a bowl of perfectly cooked rice. How does it do this? How does it know when the rice is “just right” since we don’t all have the same taste what “just right” is.

Keep reading as we discover and explain how this magic appliance works.

How does a rice cooker work?

A rice cooker works using a 2-to-1 ratio of water to rice in most cases, with a thermometer measuring the internal temperature of the water and rice inside. The water starts to boil and turns to steam at 212℉ and soaks into the rice. The cooker automatically shuts off or switches to warm when this happens.

You probably have cooked rice manually, who hasn’t, right?

It cooks fast, but you have to keep watch over it to make sure it doesn’t overcook.  Sometimes it burns to the bottom of the pan. Other times it’s mushy. Yet other times, it’s crunchy.

So annoying!

Thankfully, there is a kitchen appliance that will cook perfect rice every time.  Let’s hear it for kitchen appliance science and the invention of the rice cooker!

So, how does this appliance work? 

To make rice with this appliance you fill the metal bowl with a 2:1 ratio of water: rice and turn the unit on, which activates the heating element and thermostat under the bowl. Because they make the bowl of thin aluminum, it heats and conducts that heat to the rice and water.

Inside the rice cooker, the heat source heats the rice bowl while the thermostat controls the heat source and measures the cooking bowl’s temperature.

As it cooks, the water begins to boil.

The bottom of the bowl will reach a maximum of 212℉, causing the water to turn to steam. That steam carries the heat off through the rice.

The rice is now absorbing the water, which is making the starch in the rice, keeping in mind that starch is primarily sugar, a bond with the hydrogen in the water. The rice grains then gelatinize, or in simple terms, connect.

If you kept adding water, it would turn to mush.

But if you kept the heat on, it would start to get crunchy and eventually burn. Luckily, the rice cooker has a sensor that monitors both the temperature of the bowl and how fast it rises. The less water in the bowl, the faster the temp rises.

When that reaches a certain level, the rice cooker knows the rice is done and shuts off.

How long does it take to cook rice in a rice cooker?

As a general rule, in a rice cooker, short and long-grain white rice will take 15 minutes. Basmati and Jasmin take up to 20 minutes, and brown or wild rice will take 45-50 minutes.

By now, we all can agree that having a rice cooker can make meal preparations to a new level, making it possible for foolproof rice using these one-button appliances.

When the rice cooker, water, and rice are all properly assembled, you can have perfect rice ready in 15 minutes and the basis for your meal, adding beef, or chicken, with assorted vegetables and a dash of soy, teriyaki, or other flavorings.

Here are cooking times for all the most popular types of rice:

Type of rice How much water to rice Cooking time
Short grain white rice  1 1/2 cups water to 1 cup rice 15 minutes
Long grain white rice  1 3/4 cups water to 1 cup rice 15 minutes
Parboiled rice 2 cups water to 1 cup rice 20-25 minutes
Basmati rice 1 1/2 cups water to 1 cup rice 15-20 minutes
Jasmine rice 1 1/2 cups water to 1 cup rice 15-20 minutes
Long grain Brown rice 2 1/2 cups water to 1 cup rice 45-50 minutes
Wild rice 2 1/2 cups water to 1 cup rice 45-50 minutes

Note that parboiled rice, sometimes called converted rice, refers to rice that has already been partially cooked, like Uncle Ben’s.

Manufacturers recommend waiting 15 minutes before removing the lid, this allows the rice to rest. It gives the rice a pleasant texture.

There are two rice cooker varieties available: cool-touch and pot-style, with the pot-style being the less expensive and easiest to use. The pot-style cookers are available in various sizes ranging from three cups to thirty cups of uncooked rice and have one button system (the ease of using it) and come with a removable pot.

The cool-touch models cook four to ten cups of uncooked rice and have a digital readout. The pot is not removable, and the lid is hinged. Those who use the cool-touch say the moisture retention is better and that they are easier to carry.

Digital features like delay timers are a plus.

What’s the point of a rice cooker?

The point of a rice cooker is to get perfect rice, every time, with minimal effort or guesswork. With a rice cooker, you can set it and forget it, with little danger of the rice getting mushy, crunchy, or burned. 

But that’s only the beginning.

Ultimately the point, as with Instant Pots, Crock-Pots, and other small kitchen appliances, is convenience. Look at what I found others use their rice cooker for:

A Hot Breakfast

Using a little less milk (or water), you can make hot cereals or oatmeal and the keep-warm function keeps the food from getting cold and/or gooey. This is a great feature for those that get up later than others. Add fruit, nuts, or whatever you want to it.

Steamed Vegetables

Some rice cookers, especially Japanese ones come with a steamer rack, perfect for cooking cut vegetables, potatoes, or tofu. You can also cook chicken breasts, fish fillets, or shrimp, all in one pot. 

No-Stir Risotto

Using the “slow” option, sauté onions in butter with lid off/open then add 1:4 ratio of Arborio rice: broth/wine and cook for twenty-five minutes. When finished, add herbs and grated cheese.

Bean, Soups, Stews

With a good amount of liquids and plenty of time, you can make a wonderful pot of a split pea soup with ham, vegetable stew in a rice cooker. It will need to simmer for a long time but won’t boil over or scorch.

Poached Fruit

Make healthy desserts and snacks with your rice cooker out of fresh fruit that has simmered in juice maple syrup or wine, including apple sauce.

How do you fix undercooked rice in a rice cooker?

If a rice cooker undercooks rice, add 1/4 cup of water to the rice cooker, power back on, and cook for 3-5 minutes, and then allow it to rest with the heat off for 5 minutes.

When something like a rice cooker that is supposed to make our lives more convenient lets us down, it’s frustrating! Luckily, if you underestimated the time or water in your rice, it’s not hard to fix.

Here are those steps in greater detail:

  • Press a grain or 2 with your fingers to gauge how undercooked it is
  • Add a small amount of water to the rice cooker (how much depends on how undercooked the rice is – the more undercooked, the more water you’ll need, but start with about 1/4 cup)
  • Turn your rice cooker back on
  • Cook for 2 minutes
  • Turn off the heat, but leave the lid closed for 5 minutes

If your rice continuously comes out crunchy, this is caused because the seal isn’t sealing properly on your rice cooker. This is allowing steam to escape instead of cooking the rice.

Now some rice cookers have a locking lid like an Instant Pot. Others just have a lid you set on it like a Crock-Pot.

If you have a lid that isn’t a locking lid, you can lay a clean dish towel between the lid and pot, This will keep the steam inside where it is can cook the rice.

You want to make sure the towel isn’t close to any burners or an electrical cord. If your rice comes out mushy, make rice pudding and start over for your dinner dish!

Undercooked rice can usually be avoided by following the one cardinal rule when cooking rice:  Do Not Open the Lid!

Why does my rice burn in the rice cooker?

If rice burns in a rice cooker the possible reasons include high starch levels in the rice (arborio has the most and basmati has the least), too high of rice to water ratio, or improperly set temperatures.

A rice cooker’s main purpose is to provide you with the best rice ever, however, that isn’t always the case. But the biggest culprit in burned rice is usually just a cheap rice cooker.

Generally speaking, the less expensive the rice cooker, the thinning the inner pot is. A thin-walled pot (where you put the rice) doesn’t control the temperature as well.

But if you aren’t ready to buy a new rice cooker, try some of these things:

  1. Rinse the rice 3 times in a colander before cooking (this releases the excess starch)
  2. Make sure to use the proper water/rice ratio (I list those above)
  3. Make sure you set the temperature correctly
  4. Cooker larger batches (just cooking 1 cup of rice may not be enough quantity for your cooker to properly sense the temperature)

What if you get crunchy rice, and that wasn’t your intention?

If there is a brown/orange-ish crust, this is caramelized starch. In several parts of the world, this is a delicacy, and if you’re using an analog rice cooker, this is a common outcome.

If you’ve ever had a proper paella, you’ve no doubt tried this type of crunchy rice. But there is a difference between crunchy and burned.

But, if you don’t like a caramelized crusty rice, you usually scrape this part off the bottom of the rice and discard or use for something else.

Another option is to cook larger amounts of rice and lessen the possible ratio of “good” rice to scorched rice.

Or maybe it is time to bump up to a better rice cooker model with more sophistication like microprocessor-controlled units. This type of rice cooker will adjust the temperature while cooking, minimizing, possibly eliminating, the possible scorching.

Why does my rice cooker boil over?

Generally, overly starchy rice such as arborio is the primary cause of a rice cooker boiling over. As starchy rice cooks, it forms bubbles as it mixes with the water. This creates expansion inside the cooker that will eventually spill over. Use less starchy rice to avoid this.

That’s one reason many people suggest rinsing the rice a few times first in a colander (as I suggested above).

Of course, it could be that you just used too much water or went over the capacity of your rice cooker. But a more common cause is super-starchy rice.

What are the best types of rice to use?

Luckily, I cover all the possible causes and solutions in a recent article. I even get into which kinds of rice have the least amount of amylopectin starch which are the worst offenders for causing a boil-over.

Just click that link to read it on my site.

What is the best rice cooker on Amazon?

Well, the #1 best-selling rice cooker on Amazon is the Zojirushi NS-TSC10 (click to see the current price on Amazon).

So if you need the Cadillac of rice cookers, this is the one you want.

This thing is amazing! It features:

  • Automatic keep warm, extended keep warm, and reheating cycle
  • 2 delay time settings (get it set up to cook later!)
  • Retractable power cord
  • Different settings for white rice, brown rice, porridge, cakes, steamed vegetables, and more!
  • It can be used as a slow cooker too!
  • Removable bowl and steamer are dishwasher safe

CLICK HERE TO SEE IT ON AMAZON

But at over $150, it’s also, by far, the priciest rice cooker on Amazon. 

So for that reason, I wanted to also mention the best budget rice cooker on Amazon too. So for that one, I really like the Cuisinart CRC-400 (click to see on Amazon).

Like the Zojirushi, it also has well over 1,000 reviews and over a 4-star rating. But this one comes in at well under $50!

Here are some of its best features:

  • Steams rice, meats, and vegetables
  • Automatically switches to warm when done cooking
  • Use the built-in tray to steam other foods while the rice is cooking
  • Chrome-plated handles stay cool to the touch

CLICK HERE TO SEE IT ON AMAZON

Final thoughts

In this article, we took a look at the world of rice cookers.

We examined why you might want one, and how they work. We also troubleshot a few common problems and looked at the proper time and water amounts for all of the most common types of rice.

But ultimately, we answered the question of how does a rice cooker knows when the rice is done.

The answer to that is a sensor that gauges the temperature of the metal insert bowl that sits inside the cooker. As it increases temperature as the water cooks into the rice, the cooker knows when it’s done and shuts off.

The rice cooker is a wonderful addition to your kitchen appliances, and maybe one of the most versatile ones yet!

Just about every time it creates the perfect rice for any dish, any error is typically user error. Most errors can be salvaged though, so you really can’t mess up with a rice cooker.

If you’re looking to buy any small kitchen appliance, don’t forget to check out my Recommended Products Page (click to see my page) which breaks down all my best picks by category.

I always hand-select items that I either own, have used, or have researched well to ensure they are great items. I also give not only top of the line as well as inexpensive alternatives so my choices work for any budget.