How Much Ice Do I Need?

Ice keeps your food and drinks cold when you’re on the go or having a party. During your workday or during your time off, you want to have enough ice so your food and drinks stay cool. So how much ice do you need? It’s easy to overestimate, and end up dumping a lot of extra ice. But you don’t want to underestimate and end up with lukewarm food and drinks. Using math and science, let’s see how much ice you need for each occasion, including an indoor party, workday, fishing trip, and more. We’ve updated this post in 2024 to improve our ice calculations and give you a better estimation for more situations.

How Much Ice Do I Need? How Do I Know?

How much ice do I need? How do I know? Maybe you’ve asked yourself this question when you’re preparing for an outing, party or workday. To calculate how much ice you need, let’s start with a few estimations.

A single ice cube will melt in about 90 minutes in a 75°F room, 60 seconds in hot water, and about 15 minutes in cold water.
With an ice pack or bag of ice included, an insulated lunch box will stay cold for about 2 to 2.5 hours.
A 3lb (1.5kg) bag of ice left in a 73-75°F room, without insulation, will melt in about 5-7 hours.
Larger coolers vary a lot in their cold-keeping capacity. Styrofoam coolers can prevent melting for about 12 to 24 hours, while higher-quality coolers can keep ice for as much as four days.

There are many factors that can affect these times, and parties or workdays aren’t exactly laboratory settings. The surrounding temperatures, the level of insulation, size and shape of ice cubes or blocks, use of salt or sugar, and other factors can all affect melting time. Keep in mind that these are rough estimates.

How Much Ice Do I Need for a Party?

So, how much ice do you need for a party? A few simple calculations can help you land on the perfect amount. First, how many guests do you expect? And how long is the party going to be? And, finally, will you be storing your ice at room temperature, or in the freezer?

Say you’re having a dinner party, and you’re hosting 12 guests. Your party starts at about five o’ clock, and goes until ten o’ clock. You’re storing your ice in the freezer, so it’ll stay frozen through the duration of the party. Assume your guests each enjoy one drink per hour, with an average of three ice cubes per drink (some will surely use more, but others might not use any). Twelve guests multiplied by five hours is 60 drinks. Multiplied by three cubes each, that’s 180 ice cubes! An average ice cube is about one ounce, which translates into about 16 cubes per pound of ice. That’s about 11.25 pounds of ice. With one ten-pound bag of ice, you’ll be pretty close to the amount of ice you’ll need for a dinner party with 12 guests.

Assuming your ice isn’t melting in storage, this is a good equation for estimating how much ice you need for a party:

(Guests x Hours) x 3 = total number of ice cubes required
Total number of ice cubes / 16 = pounds of ice required

How Much Ice Do I Need to Keep My Lunch Cold?

How much ice do you need to keep your lunch cold during your workday? The safe temperature for food is 40°F or lower. As previously mentioned, a regular lunch box with an ice pack will maintain this temperature for only about 2 or 2.5 hours. More ice, a bigger cooler, and better insulation will extend this time.

If you don’t have access to refrigeration, but you’ll be working indoors at room temperature (73-75°F), and you expect to have lunch about three or four hours into your work day, fill your lunch box with sealed bags of ice and surround your food or drink items. To be on the safe side, you might use a food thermometer in your lunch box to make sure the temperature stays low. Or, use a bigger cooler and fill it with ice. A simple, affordable, Styrofoam box filled with ice will keep your lunch cold for about 12 hours, so you won’t have to worry.

So, how much ice do you need to keep your lunch cold? Well, here are some approximations:

Keep your lunch cold for two to three hours: A lunch pail filled with two frozen ice packs or about two dozen ice cubes will keep foods and drinks cold for about two or three hours.
Keep your lunch cold for about 12 hours: A larger cooler or Styrofoam box, holding between 12 and 25 cans, with between 5 to 10 pounds of ice should stay cold for about 12 hours.

How Much Ice Do I Need for a Fishing Trip?

How much ice do you need for an outdoor excursion, like a fishing trip? There are a lot of factors to consider here, including the outdoor temperature, time, number of fishers, and whether or not you’re using ice to keep your catch cold as well as your lunch. All of these factors make it difficult to estimate exactly how much ice you need for a fishing trip. However, a large, high-quality cooler filled with ice should keep your food and drinks cold for at least 12 hours, even if the temperatures get very hot.

If you’re keeping your catch cold as well, it’s a good idea to bring a secondary cooler filled with ice. While you could put your lunch and your fish in the same cooler, separation will help to prevent the transfer of bacteria from raw fish onto your lunch and drinks. Remember that ice doesn’t kill bacteria; cold temperatures just prevent most bacteria from multiplying.

So, how much ice do you need for a fishing trip? Here’s some approximations:

A 12-hour fishing trip for your lunch and drinks: A 50-quart cooler holds about 1600 ounces, or 1600 one-ounce ice cubes (about 100 lbs of ice). Leaving a bit of extra room, fill the cooler with about 40 lbs of ice (4 bags weighing 10 lbs), and your lunch and drinks will stay cool all day in hot weather.
A 12-hour fishing trip with extra ice for your catch: To keep bacteria from raw fish away from your food or drinks, bring an extra cooler for your catch. Fill a second cooler halfway with ice for your catch. So, you’ll need approximately 2 50-quart coolers, each holding 40 lbs of ice.

How Much Ice Do I Need for a Beach Trip?

A beach trip might be the most extreme test of your cooler and your ice. Once again, numerous factors make it difficult to estimate exactly how much ice you’ll need for a beach trip. Generally, a large, insulated cooler filled with ice will last at least 12 hours. A few tips can help you extend this time, even if your cooler isn’t the highest-quality.

First, chill your cooler and your cold items beforehand. This way, heat isn’t transferring from room-temperature items into the ice. If your cooler isn’t well-insulated, a layer of aluminum foil or bubble wrap can help. When you’re at the beach, cover the cooler with a white blanket or towel to reflect the sunlight away. Also, bury your cooler a bit into the sand, if you can. This will insulate the cooler a bit more and slow the melting process. Finally, if you can, release the water that collects as the ice melts—the molecules in water are more tightly-packed, so they’ll transfer heat and melt the ice faster than the air.

How much ice do you need for a 12-hour beach trip? Fill a 50-quart cooler a bit less than halfway with ice (about 40 lbs of ice). Then, cover the cooler with a white blanket or towel. Also, release the melted water in the cooler periodically throughout the day.

How Much Ice Do I Need for an Ice Bath?

An ice bath has become a popular trend online for stress relief, a wake-up jolt, or for soothing strained muscles. Though it’s important to be careful with this trend, since ice bathing can be harmful for people with heart conditions or abnormal blood pressure, it can be enjoyable for some. But how much ice would you need for an ice bath?

You don’t need to completely fill your tub with ice for an ice bath. Though tub sizes vary, estimates suggest that the average tub, with a person included, needs about 30 gallons of water. You can use half this amount of water, and fill the rest with ice to get an invigorating cold plunge. Each gallon of water equates to about 8 lbs of ice. So, you’ll need between 10 and 15 gallons worth of ice, which equals about 80 to 120 lbs of ice. If this seems like a lot of ice, don’t worry; you can fill your tub with cool water and just a bit of ice, and still enjoy a brisk dip.

How much do you need for an ice bath? Fill your tub about one-fourth full with cool water. Then, add about 80 lbs of ice (8 10-lb bags). Or, add less ice and top off your tub with water. Make sure your tub is less than half-full, so it doesn’t overflow.

How much ice you need depends on what you’re using your ice for. Sometimes, it’s okay to approximate. But, if you’re packing perishable food, it’s always better to have more ice than not enough. Use a food thermometer to be safe, and remember that bacteria levels double every twenty minutes at temperatures between 40 °F and 140 °F. It’s always better to be on the safe side when it comes to perishable foods; nothing will ruin a beach trip or holiday parter faster than foodborne illness!