I was making some tea and was wondering how long does it take to boil a cup of water? I made one small cup of tea of 4 ounces, so it always takes only a minute or two. But, I wanted to know more.
How long does it take to boil water? It takes 90 seconds to boil 1 cup (250ml) of 59°F (15°C) water, in a 1 kWh (kilowatt-hour) efficient water heater. It takes 2.5 minutes to boil 2 cups of water, and 5 minutes to boil 4 cups of water.
But, we don’t normally use very efficient water heaters, so in real life it usually takes a bit longer. There are always inefficiencies in converting power to heat, and some heat losses from the water as the temperature increases.
Now, let’s see how much does it take to boil different amounts of water on different heaters, and how can we calculate this by ourselves.
How Long Does It Take for Water to Boil?
As I mentioned before, it takes about 90 seconds to boil 1 cup (250ml) of 59°F (15°C) water, in a very efficient 1kWh (kilowatt-hour) water heater. This is assuming average atmospheric pressure (1 Atm), constant increase in heat and no heat loss.
There are many ways to boil water, and various kitchenware to use. The time it takes for water to boil depends on several factors:
- the rate at which you add heat
- water temperature at the start
- the efficiency of your heater
- the amount of water you need to bring to a boil
- the atmospheric pressure
- impurities in water
Big factor is the water heater used, and the temperature of the starting water. If you were to try to boil a water close to a freezing point, then it will take much longer.
How to Calculate How Long to Boil Water
This is easy to calculate.
It takes 4.2 J (joules) to raise a gram of water by 1°C.
(Or, 8.33 BTU to increase one gallon of water by one degree F)
So, if your water is at 15°C (59°F) and you want to boil a liter (4 cups) then:
4.2 * 1 * (100 – 15) = 357s (or 6 minutes) in a 1kilowatt heater.
Or 3 minutes in a 2 kWh heater.
For 1 cup of water (250ml) that’s:
4.2 * 0.25 * 85 = 89.25 (or about 1.5 minutes) on 1kWh heater, or 45s on 2kWh heater.
But, in real life we don’t use ideal water heaters, and there is a lot of heat loss and inefficiency in converting power to heat, so it takes longer.
How Long Does It Take to Boil 2 Cups of Water?
Using a 2 kilowatt efficient water heater, it takes 90 seconds to boil 2 cups of water (0.5kg) from 59°F (15°C) to 212°F (100°C).
But, this is an ideal situation with a highly efficient water heater, and in real life it always takes longer. Also, a boiling point of 212°F (100°C) is not always a constant.
On a stove it would take about 5 minutes to boil 2 cups of water, depending on the stove and the factors I mentioned before. Usually it’s 2 minutes per cup of water. It would take a lot longer to boil water on a grill.
In a microwave, it would take about 1.5 to 2 minutes to boil 2 cups of water.
In oven it would take about 15-20 minutes for a water to reach boiling point.
How Long Does It Take to Boil Water in a Microwave?
A 1.5 kWh microwave will take about 1 to 1.5 minutes to boil a cup of water. A 700-800 watt microwave will take about 2.5 to 3 minutes. It takes 3 to 5 minutes to boil 4 cups of water (1 liter) on a typical microwave.
On first glance, it looks too long, but there are always losses of heat from the water and the inefficiencies in converting the power to heat. The time it takes to boil water will depend on the energy and the efficiency of your microwave.
When boiling in the microwave, consider adding a spoon of sugar or salt to help with the bubbles when the temperature reaches the boiling point.
Note: Use microwave safe container to boil water in. Do not place lid in the container. Always read the manual that came with the kitchen appliance to make sure to follow the rules.
How Long Does It Take to Boil Water on a Stove?
It will take about 8 to 10 minutes to bring 4 cups (1 liter) of water to a boil, depending on the stove. Usually, it’s 2 minutes per cup of water, depending on the stove.
On a propane stove, it takes 8 minutes to boil 4 cups (1 liter) of water.
On a natural gas, it takes 7 minutes to boil 4 cups (1 liter) of water.
On induction cooktop, it takes 5 minutes to boil 4 cups of water (1 liter).
On electric stovetop, it takes 10 minutes to boil 4 cups (1 liter) of water.
How Long Does It Take to Boil Water in a Kettle?
To boil 4 cups (1 liter) of water in 1500 watt kettle will take about 4 minutes. If you used a stronger 2400 watts kettle, for example, it would take you 2-3 minutes to boil 4 cups (1 liter) of water.
This is the time if we assume water was 59°F (15°C) before we started boiling, and the atmospheric pressure was the regular 1atm.
How Long Does It Take to Boil 4 Quarts, 6 Quarts and 12 Quarts of Water?
There are many ways to boil a water, and various burners out there.
It takes 11 minutes to boil 4 quarts of water on a 15,000 BTU burner, from 50°F to 212°F.
It takes 5 minutes to bring 4 quarts (1 gallon) of water to a boil on a good Natural Gas burner stove, or 9-10 minutes on a 18,000 BTU burner. And usually 15 to 20 minutes on a 7,000 BTU stove.
On a 15,000 BTU burner, with water starting at 50°F it would take 12-15 minutes for 6 quarts (1.5 gallons) of water to boil. And 20-25 minutes to bring 12 quarts (3 gallons) of waters to a boil.
How to Make Water Boil Faster
Fastest way to boil water is by using electric kettle or a microwave. It can take only 1-2 minutes to boil a cup of water using a good electric kettle, or 1 minute for a microwave set on high.
Important note: use the safe microwave container. Keep in mind the water might explode when you boil in a microwave oven (including your mug). Never use metal in the microwave.
Here are some of the ways to bring water to a boil faster:
- Starting with hotter water will boil faster
- Use induction cooktop
- More surface = faster boil (in skillet will boil faster than in a saucepan)
- Use less water and more heat
- If you stare at a pot of water, it takes longer to boil…
Does Salt Help Water Boil Faster?
No, salt doesn’t help water boil faster, but it does make your food cook faster. What the salt does is increase your water’s boiling point, called boiling point elevation, making it longer to reach it.
It’s an old wives’ tale that salt makes water boil faster, but what it does is increase the boiling point making the water hotter when boiling. This cooks the food faster, but it does not make the water boil faster.
Hopefully you learned something useful today. Keep reading, I got some cool stuff up in here!