Curious to know how long it takes for ice to fully freeze?
While timing will depend on a lot of variables, a standard freezer at standard freezers temperature usually takes 3-4 hours to freeze cubes of water.
In this article, we'll break down exactly what variables effect freezing time and how you can use this knowledge to freeze water faster.
Freeze Time Depends on...
Size of the Cube
Smaller cubes have a higher surface area to volume ratio, and more surface area allows heat to escape into the environment so that small cubes will freeze more quickly.
If you want faster ice, make smaller cubes.
Some materials transfer heat better than others. Metals like aluminum or copper transfer heat away from the water.
Plastic, glass, and silicone act as insulating agents, preserving heat in the water.
If you use a plastic container, the ice will freeze faster than if you use a glass or silicone container.
Minerals and Ions in Water
Minerals or solutes dissolved in water make it harder for water to freeze; solutes decrease the freezing point of water.
Most of us are familiar with this effect from salt scattered on winter sidewalks.
The salt doesn’t actually “melt” the ice;
instead, it dissolves into thin layers of surface melt water on the sidewalks and lowers its freezing temperature so that the weather must get even colder before the sidewalks can freeze over again.
So, for faster freezing, use purified water.
Air pressure is lower at high altitudes, which slightly increases the freezing point and lowers the boiling point of liquids.
The change in freezing point at high altitude is not as dramatic as the change in boiling point, so you probably won’t notice the difference outside of a physics lab!
So, for faster freezing, bring your freezer up to higher altitudes.
Accompanying food in the freezer
Warm or partially frozen food in the freezer lowers the ambient air temperature, slowing the speed of heat transfer away from the water.
This delays the rate at which it freezes into ice, but it will hardly be noticeable.
So, for faster freezing, don't add food to the freezer.
How to Freeze Ice Faster
Some tricks to freeze water faster include...
1) Making smaller ice cubes
2) Freeze in a metal container
3) Making sure everything is already frozen in your freezer.
4) Use a freezer that is set at a colder temperature.
Also, try making your cubes with hot water. That’s right! This last counterintuitive observation is called the Mpemba Effect.
The Mpemba Effect
In a 1969 paper tantalizingly titled “Cool?”, Erasto Mpemba described a cooking class he had taken as a schoolboy in Tanzania.
While making ice cream, he observed that a hot solution froze faster than a cold solution.
Although its mechanism remains controversial, this phenomenon has been replicated over the years.
The Mpemba Effect is attributed to everything from convection currents to micro-bubbles.
Using the Mpemba Effect to Speed Up Freeze Time
Try it yourself!
For quick-freezing ice, place hot (above 113°F, but not boiling) water in an uncovered ice cube tray, and you’ll observe that it transforms into ice approximately 15% faster than cold water.
Techniques to speed this up even more are...
1) Use a container that has a large surface area, such as a baking dish.
2) Stir the water constantly as it cools. This prevents the formation of ice crystals at the edges, and allows the entire batch to freeze more quickly.
Best Freezer Temp to Freeze Ice Faster
When it comes to freezing ice cubes as quickly as possible, the freezer temperature is an important factor to consider.
The ideal temperature for freezing ice cubes is -18 degrees Celsius (-0.4 degrees Fahrenheit).
If your freezer is set colder than this, your ice cubes will freeze slightly faster. If your freezer is set warmer than this, your ice cubes will freeze slower.
But if you're using an ice maker, contrary to intuition, colder is not always better. If an ice maker's pipes freeze, the machine will lose air circulation, crippling its ability to produce ice.
A temperature between 0-5°F is ideal for maintaining a working ice maker while safely preserving stored food.
How Long Does it Take to Freeze Popsicles?
When it comes to making popsicles, there's nothing more frustrating than waiting for them to freeze solid.
Depending on the recipe and the freezer temperature, it can take anywhere from a few hours to overnight.
Technically, water freezes at a rate of approximately 3 hours per 100 cm3 (or about 3.4 fluid ounces–about the size of a child’s popsicle mold) at a typical freezer temperature of 0°F.
However, it may take popsicles double that to freeze completely solid because their freezing temperature is depressed from the addition of solutes like sugar and flavorings and because they are often insulated in thick plastic molds.
The best freezer temperature to freeze popsicles is -18 degrees Celsius (-0.4 degrees Fahrenheit). At this temperature, popsicles will freeze in an average of two hours.
Tips for Making Cubed or Crushed Ice at Home
There are a few different ways to make cubed ice at home, but the most popular method is to use an ice cube tray.
To make cubed ice with an ice cube tray, fill the tray with water and freeze it for several hours.
Once the cubes are frozen solid, you can leave them in the tray, or remove and store them in a freezer-safe container for easy-access.
You can also use disposable ice cube bags, which are cheap, easy to use, and convenient if you need a lot of ice at once.
There are a few different ways to make crushed ice at home, but the most popular method is to use an ice crusher.
If you don't have an ice crusher, you can use a blender or food processor to crush the ice. Just be sure to leave some larger pieces intact, so that the ice doesn't melt too quickly when it's added to drinks.
Another option is to freeze water in plastic bags. This is a quick and easy way to make crushed ice, and it's perfect for margaritas or smoothies.
Just fill a plastic bag with water, seal it shut, and freeze it for a few hours. Once it's frozen solid, you can break it into smaller pieces by gently hitting the ice with a hammer or mallet.
How to Make Ice Melt Slower
Try this trick to keep your ice unmelted longer: make large cubes from just-boiled water.
Boiling water before freezing eliminates air bubbles. Not only does this result in lovely translucent ice, but it also slows down melting.
And, just like tiny ice cubes freeze faster, big ice cubes melt slower! This is also a function of surface area; large cubes transfer less heat from the environment to the cube surface, meaning they melt less quickly.
You can also use a freezer that is set at a colder temperature. This will cause the ice to last longer than if the freezer were set at a higher temperature.
Another way is to add salt or sugar to the ice. The salt or sugar helps to lower the freezing point of water, which will keep the ice from melting as quickly.
You can also use a container that has a large surface area, such as a baking dish. This will help to slow down the melting process.
And finally, you can stir the ice constantly as it melts. This will help to distribute the heat evenly and prevent the ice from melting too quickly.
Does an Ice Maker Make Ice Faster than an Ice Cube Tray?
A properly working ice cube maker should work much faster than an ice cube tray.
It freezes water in metal molds, which helps transfer heat away, cooling the ice more quickly.
It also uses refrigerant in compressor coils to cool trays (the refrigerant does not come in contact with the ice) rather than relying only on the ambient temperature of the cold air.
Not only is it a pain to have to go get ice, but it can also be expensive. And if you're like most people, you probably don't have an endless supply of ice in your freezer.
Freezing and melting are governed by the laws of physics, so you may have thought there wasn’t much you could do to change it. Now you know that you can nudge the physics of freezing in your favor.
With our handy guide on how long it takes ice to freeze, you can utilize these tips, and you'll never have to worry about being caught without ice again.
Great article, however, Erasto Mpemba, not Ernesto.
Wow that is embarrassing :/
Thank you for the heads up. I really appreciate you taking the time.
I’ve changed the name to its correct spelling and linked his Wikipedia bio.
Hot water absolutely does NOT freeze faster. I am a refrigeration technician and have countless hours of training in regards to temperatures. It's a simple mathematical equation. Q = MC Delt T. The colder the water, the faster it will reach a cooler temperature when trying to lower it. Hot water takes more time to cool. Period.
Please do your homework before posting incorrect articles.
Thanks for getting in touch about the Mpemba effect. You’re right—it’s definitely controversial! Even the authors of a paper in Scientific Reports express doubts about it, since they were unable to replicate it in the lab. Yet, the same paper shows that the effect is possible and is NOT a breach of physics or chemistry (Burridge & Linden, 2016).
Yet over the years, other scientists have produced the Mpemba effect in the lab. The most interesting of these is a 1996 paper that demonstrated the effect under certain conditions—namely, when the samples were covered, which prevented heat loss by evaporation. In 64 of 108 tests, this lab observed that hot water froze faster than cold, and they developed a theory about why. They point out that the convective motion of hot water can switch to turbulent flow, while the convective motion of cold water can’t. Their thought is that there may be a “critical value” for the Rayleigh number, above which the natural convection in the water changes from laminar to turbulent, IF there is also some kind of disturbance in the system, which explains why it doesn’t always happen. Because water has a maximum density at a temperature above its freezing point, there is an inversion of the flow field as the liquid passes through the temperature of maximum density (4°C). This inversion is the mechanism that can trigger turbulent flow, resulting in a faster freezing rate and therefore a reduction in time to freeze (Maciejewski, 1996).
It is also worth noting that water is not the only substance in which this effect has been observed. In fact, a recent paper in the prestigious journal Nature experimentally demonstrates that this effect occurs in a wide range of substances, including water. True, their conditions are not ones likely to be found in a home kitchen, since they were setting up an experiment that would apply to many colloidal systems (not only water!) (Kumar & Bechhoefer, 2020).
In summary, scientists from Aristotle and Descartes to modern physicists have observed (but also questioned) the Mpemba effect. Studies indicate that it is definitely real, but probably pretty hard to observe, because the conditions in the real world are unpredictable and the actual effect itself is quite small.
Let me know if there is anything I didn’t address 🙂
Burridge, H. C., & Linden, P. F. (2016). Questioning the Mpemba effect: hot water does not cool more quickly than cold. Scientific Reports 2016 6:1, 6(1), 1–11. https://doi.org/10.1038/srep37665
Kumar, A., & Bechhoefer, J. (2020). Exponentially faster cooling in a colloidal system. Nature 2020 584:7819, 584(7819), 64–68. https://doi.org/10.1038/s41586-020-2560-x
Maciejewski, P. K. (1996). Evidence of a convective instability allowing warm water to freeze in less time than cold water. Journal of Heat Transfer, 118(1), 65–72. https://doi.org/10.1115/1.2824069
We also have a pdf of the Maciejewski article and we’d be happy to share it with you.