23 easy steps to make long-lasting homemade ice packs for lunch box and coolers

Post In: food safety
23 easy steps to make long-lasting homemade ice packs for lunch box and coolers

Need to cool down? Bumped your knee? Want to keep your meals from going stale? You know just what you need to address these: an ice pack. 

In 1959, the first instant cold pack aimed at keeping food and beverages chilled was patented by an inventor named Albert A. Robbins. It wasn’t until 1971 that hot and cold packs were used to treat soft tissue injuries thanks to the modifications done by Jacob Spencer. 

Food preservation and pain relief are only two of the many reasons for having a steady supply of ice packs at home. By keeping everything chill, it seems you can be, too. 

If you don’t have an ice pack ready for your lunch box, here’s how you can make one in a jiffy. The best part? You don’t need to have MacGyver-level skills to master these homemade ice cooler hacks. 

Let’s discuss two important questions about food storage before proceeding.

How long does it take for food to spoil? 

The US Food and Drug Administration (FDA) recommends the two-hour rule, suggesting you should never allow foods that require refrigeration to be kept in room temperature for more than two hours; or one hour if the ambient air temperature is above 90 degrees Fahrenheit (32 degree Celsius). 

Even at home, it is best to keep foods chilled to prevent foodborne illnesses. Foods kept in proper (cold) temperatures prevent or slow down the growth of several bacteria, among them listeria, e. coli,  and salmonella, that can make us sick. The FDA further advises to keep the refrigerator at 40 degrees Fahrenheit (4 degrees Celsius) or below, and the freezer at  0 degrees Fahrenheit (-18 degrees Celsius) to reduce the risk of bacterial growth or proliferation in our food. 

Is an insulated lunch bag enough to keep food warm or cold?

Yes, for about two hours if it’s warm, and up to three hours if it’s cold. However, this largely depends on other factors such as the type of bag and insulation used, as well as the environmental temperature. 

Ice packs, whether heated or frozen, can extend these temperatures for up to four hours, so it is best to put these ice packs in your child’s lunch box not only to keep them fresh, but, more importantly, safe.  

Now that we’ve answered the two most important questions, let’s proceed to our do-it-yourself ice pack-making business, shall we?

DIY Ice Packs Instructions 

If for some reason you can’t get hold of reusable ice packs available in-store or online, here are some cool DIY ideas that won’t burn your pocket.  

Check out these easy homemade lunch cooler hacks below:

Corn syrup

How to do it: 

  1. Put 2 cups of water and 1 cup of corn syrup in the plastic bag. 
  2. Place the bag upside down in a bigger bag to prevent leakage. 
  3. Pop in the freezer for a few hours.   

Advantage(s): Can fit anywhere in your child’s lunch box; also keeps chilled for an ample period. 

Disadvantage(s): If you don’t secure the plastic bag, it may leak and leave a mess in your child’s lunch box. 


How to do it:

  1. Wet a clean sponge, allow it to completely soak up as much water as it possibly can, as the frozen water absorbed by the sponge provides the cold. 
  2. Squeeze excess water. 
  3. Put the sponge in a resealable plastic bag. Besides avoiding a mess, the plastic bag allows the sponge to reabsorb thawed water, allowing for its reuse.
  4. Freeze. 

Advantage(s): Keeps cold for longer periods.

Disadvantage(s): Freezes solid and may take a bigger space compared to other types of DIY ice packs. 

Salt and water

 How to do it: 

  1. Mix equal parts of salt and water (for instance, 2 cups each). 
  2. Place the mixture in a large resealable plastic bag. Salt changes the water’s freezing point so this mixture doesn’t go rock solid from the freezer.   

Advantage(s): Can fit anywhere in your child’s lunch box, and capable of keeping food fresh for a reasonable period.

Disadvantage(s): Will create a salty mess if it leaks and mixes with your child’s food

Rubbing alcohol

How to do it: 

  1. Combine 1 cup rubbing alcohol and 2 cups water. 
  2. Place the mixture in a resealable bag.
  3. Freeze the bag for hours or keep frozen until needed. 

Advantage(s): Remains flexible even when frozen, so it can fit anywhere in your child’s lunch box.

Disadvantage(s): Not safe if it leaks in your child’s food.

Liquid dish soap

How to do it:

  1. Pour ½ cup of dish soap into a resealable bag. 
  2. Make sure to remove the air inside the bag before sealing it. 
  3. Lay it flat in the freezer and wait until ready to use.

 Advantage(s): Flexible and fits into small or tight spaces.  

Disadvantage(s): May not keep cold for long.

Additional DIY ice pack hacks: 

1. Simply fill your resealable plastic bags with water, so you have ice blocks ready anytime you need them. Just make sure the bags are sturdy to avoid leaks. 

2. Do not throw away the free small ketchup, mustard, and other sauce packets that go with your food orders. Freeze them instead and use them to cool your food or relieve your little ones’ minor irritations. 

3. Only use resealable plastic bags that are safe and durable enough to be used  frozen. 

4. Completely remove excess air from the bag by squeezing the “unfilled” spaces prior to sealing the bag shut. This helps avoid the bag from leaking.  

 5. For extra durability, insert the mixture-filled plastic bag upside down in a bigger bag and zip to close.  

6. Do not fill the bag to the brim. Water expands when it solidifies.

7. Use vacuum sealers to close the plastic bag permanently. 

8. Is the compound too hard straight from the freezer? Wait for it to melt and add more alcohol. Adding alcohol to the mixture allows it to stay slushy and malleable even when frozen.

Because of its chemical composition, alcohol has a much lower freezing point at -114.7 degrees Celsius (-174.6 degrees Fahrenheit), compared to water’s freezing point of 0 degrees Celsius (32 degrees Fahrenheit)

9. If you want your kids to enjoy using your homemade lunch coolers, why not put a few drops of food coloring to add more fun?

What is the best ice pack cooler for a lunch box? 

For you and your child’s safety, we highly recommend these lunch box coolers. Compact and light, these Amazon’s choice ice packs are above the competition in keeping food cold and crisp for hours. They’re guaranteed safe and leak-proof, making them the best value for money lunch box ice packs in the market.

If you’re planning to take your family out for a picnic or an adventure, you definitely need serious cooling power from these big camping cooler buddies. Long lasting and nontoxic, these coolers can stay cold for up to 36 hours. Amazing, right? What’s more, they are available online, too.  

How do I make ice packs for coolers?

 While waiting for your camping cooler buddies to be delivered right at your doorstep, you can make your own using recyclable materials found in your homes. 

Simply fill the following items with water, add about two tablespoons of salt to avoid the pack from forming into a super solid block, and freeze. 

  • Empty plastic bottles – With these, you’ll have an adequate supply of water and cooler at the same time.
  • Balloons  Before engaging in an epic water balloon fight, fill up your leftover balloons with water and salt before placing them around the food and drinks in your cooler or spacious lunch box.
  • Food containers  If you’ve got plenty to spare, your containers may be used to preserve your perishables needed for your outdoor trip.
  • Wine box bladder – Do the environment a favor by reusing boxed wine containers. Wash the bladder well and fill it up with your favorite drink and freeze. It not only cools your consumables but can also be used to serve drinks, alcoholic or otherwise, while enjoying the outdoor view.
  • PVC tubes  Got some extra PVC pipes from your recent home improvement project? Put them to good use by converting them into ice tube coolers. 

Here’s how to make ice tube coolers from PVC pipes 

  1. Measure and cut pipes to the inner length of your outdoor cooler, allowing a few inches of extra space for the sealing caps on both ends.  
  2. Using PVC cement, attach the cap to seal one end of the PVC pipe. 
  3. Wait for at least 2 hours to dry.
  4. Fill the pipe at ¾ capacity with water and add two tablespoons of salt. 
  5. Seal the other end. Put a bit of pressure on the cap and allow the pipe to dry for at least 2 hours. 
  6. Freeze the pipe.

How to make ice packs last longer

Keeping your food and beverages chilled longer could spell the difference between a memorable or a miserable outdoor trip. Here are some additional tips to keep consumables colder for longer even when it’s hot outside.

Freeze your food or drinks  Frozen foods can double as ice blocks to preserve the other stuff inside the cooler. Also, freeze your child’s drinks before placing them in the lunch box to achieve the same effect. 

Pre-chill your cooler or lunch box  Filling your cooler with ice packs the night before or hours prior to leaving for your trip will keep your refrigerated food chilled for longer. This may sound like common sense, but how many of you actually do this before driving off? 

Use this trick before using your child’s lunch box, too, as long as the bag is lined with an insulator. 

Line your cooler with an aluminum insulator. Ever wonder why insulated lunch boxes have lining? Without it, heat comes in quite easily, and an insulator such as an aluminum foil will help slow down this process. 

Pack right (and tight)  Cold air sinks so place the foods you want cold for the longest time, like frozen meat, vegetables and other stuff, just above the layer of ice blocks lined at the bottom of your cooler. Make another ice layer before placing dairy products or sealed foods in resealable bags. Place the condiments, butter, cheese, dips and other food you’ll consume the soonest or most often on top. 

Make sure the spaces in your cooler are filled with ice packs because your food will get warm easily if there are spaces for the air to pass through. 

Cover the top with a thin foam sheet, a yoga mat or a woolen blanket – anything that fits your cooler, really. This cover allows for the cold air to stay in your cooler and for the warm air to keep out. 

Another useful tip is to keep your cooler away from direct sunlight. 

Bigger is better   Big blocks of ice melt slower than ice cubes, right? So use ice blocks whenever you can. If you don’t have any, use frozen water bottles to hit two birds with one stone. You can use them to keep foods chilled and drink the water in it as it begins to melt. 

Two is better than one  It’s best to keep one cooler for food and another for beverages. The latter will be, no doubt, frequently opened by kids who’d want a sip of juice every few minutes, allowing for cold air to move out and warm air to come in. 

Having a separate cooler for foods will ensure that cold air won’t evaporate quickly, allowing for prolonged freshness. 


Ice packs are a great way to keep food fresh and safe for longer hours than a traditional lunch box. 

You can make them by using household products, but when it comes to your family’s safety, it’s best to buy compact and lightweight ice packs or longer-lasting and flexible cooler buddies to make your food fresh for longer.  

Do you have additional tips you’d want to share with us? Your cool ideas are always welcome. Please share them with us here.

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