The Box-Fan Dehydrator Experiment


Alton Brown is the man.  He is, in his heart of hearts, as frugal as they come.  On his show Good Eats, he always railed against unitaskers– items which have only one purpose, and aren’t useful for anything else.  One such contraption is the food dehydrator, and Alton knows it.  There’s a classic episode of Good Eats where he builds a box fan food dehydrator and shows that dehydrated food need not come from a bag or an expensive appliance.

I’ve always wanted to try the box fan dehydrator, so today I went out and grabbed what I needed at the cheapest prices I could find.  One of the items recommended on Good Eats was a dehydrator liner, but I found that the plastic canvas carried at craft stores works just as well.  These are the heavy plastic screens used by children for their first needlepoint projects, so check the needlework aisle.

After executing on Alton’s design, I came up with a pretty cool planning tool for those of you looking to do a lot of dehydrating, but we’ll get to that later.

Shopping List
Box FanTarget$9.99
Bungee CordsHome Depot$3.48
3 Cotton HVAC FiltersHome Depot$11.91
6 Plastic Canvas (.69 Each)Michael's$4.14

My research on Amazon suggests that if you had to purchase all of these items, you would spend about as much as the least expensive dehydrator on the site, though the reviews for that mention something about melting trays, which sounds problematic.  Many people already have access to a box fan and bungee cords, so it’s possible you can spend around $15 to have a working food dehydrator.  Plus, even if you do buy all these items, at least you’re left with a box fan and some bungee cords, so at least we’re not buying unitaskers.

I’m experimenting with not eating meat at the moment, so I’m making dried fruit.  Here are the steps I went through to make dehydrated banana and strawberry.

First, I bought some bananas and strawberries (duh).  This cost me 29 cents per banana (I bought five) and $2.99 for a pound of strawberries.  I wasn’t able to get all the strawberries on the plastic canvas, but I got all but a couple strawberries on one set of mats.


This is a pretty simple process:

  1. Lay the box fan flat, suspended between two chairs so that there is ample room for airflow, aiming the direction air will flow upwards.
    IMG_3672 (1)
  2. Lay one of the HVAC filters on top of the box fan.IMG_3696
  3. Slice the fruit or meat into thin slices or strips.  If you are drying fruit, you may want to briefly toss the fruit in a bath of water and lemon juice.  The citric acid will help keep it from browning.IMG_3676
  4. Once the fruit or meat is ready, lay it on one of the plastic canvas pieces. Place the canvas pieces on the filter.IMG_3677
  5. Lay another plastic canvas on top, creating a sandwich of the item you are dehydrating.IMG_3692
  6. Place another filter on top of each sandwiched layer of food.  Some trial and error with the direction of airflow suggests that the arrows on your filter should point towards the fan (the side with the metal and cardboard backing should be on the bottom).  The total number of filters shouldn’t exceed 3-4, depending on how strong your fan is.IMG_3697
  7. Use a couple of bungee cords to secure the filters to the fan.  Don’t make it so tight that the filters get squished.IMG_3691
  8. Turn the fan on to a setting strong enough to blow air consistently through all the layers, but not so strong that it crushes the filters or causes them to buckle.
  9. Run the fan in the driest environment you’ve got.  Depending on the water content in your food, it may be 12(fruit)-48(meat) hours before it is adequately dehydrated.  You can start checking after 12 hours for fruit and 24 hours for meat, and each 12 hours thereafter.
The Result

IMG_3694Almost exactly 24 hours later, I am munching on a beautiful batch of dried strawberries and bananas.  The fruit have no added sugar or preservatives (aside from a tiny bit of lemon juice, of course) and the entire process was almost completely hands-off except for the slicing.

I learned a few things along the way, such as:

  • Be patient and don’t try to peek in the first 24 hours.  You’ll only tear the fruit apart.
  • Once they’re dry enough, even wet fruit will separate by themselves from the plastic canvas.
  • It’s better to over-dehydrate than the under-dehydrate.

This was a really fun project, but was it frugal?

Cost Comparison

IMG_3695According to an informal survey of Amazon, 1 pound of dehydrated banana costs about $7-10, and five pounds costs about $20.  So, we’re looking at about $4-10 per pound.  Dehydrating four bananas included the cost of the bananas (4 x .29 = $1.16) and the cost of the power (.02 per hour according to my calculations, so about 96 cents on the outside).  A banana is 74% water, and we want to remove 75% of the water when dehydrating something.  That means one pound of peeled bananas should produce .445 pounds of dehydrated banana.  Four peeled medium bananas is about a pound, so we’re looking at about 8 bananas x .29 unit cost + .96 electricity cost, or $3.28 per dehydrated pound for banana.  You could bring down the cost by dehydrating more at a time, and by getting a better-than average price on bananas.

Dehydration Planning

Let’s have a little more fun and create a pounds-raw-to-pounds-dehydrated conversion table.  In the following table, we calculate the dehydration multiplier by taking:

(100 – % water)/100 + (% Water / 100 * .25)

The dehydration multiplier multiplied by the weight in raw materials gives us the dehydrated weight.  Bananas have a dehydration multiplier of .445, so if you dehydrate 10 pounds of raw bananas, you get 4.45 pounds out.

Food% WaterDehydration Multiplierlbs Raw for 1 lb Dehydrated
Food% WaterDehydration Multiplierlbs Raw for 1 lb Dehydrated
White meat chicken690.48252.07
Dark meat chicken660.5051.98
Beef, eye of round730.45252.21
Beef, whole brisket710.46752.14
Worth it?

When it comes to fruit, the answer is probably “it depends on the fruit.” If you crave a high-multiplier, low-cost fruit like bananas, probably.  For low-multiplier, high-cost fruit like strawberries, this probably won’t ever make economic sense.

I am fairly certain that it is a huge savings when making your own jerky, though.  A few ounces of jerky can cost as much as $5-6 dollars, so buying meat on special and dehydrating it at home should result in big time cost savings. Beef is just under 75% water, so you’re looking at about 2.2 pounds of meat per pound of beef jerky.  If you can get a $3-4/pound deal on the meat of your choice, you can make jerky for less than half of what it would cost in the store.  Just make sure to slice very thin, and use a quality marinade to raise the pH level and kill any microbes.

This is also a great way to make dog treats at a substantial savings.

In the end, this was a pretty badass project, and I’ll definitely do it again.  It’ll be a big help in avoiding food waste, which has been one of my big problems in the past few years.  If you’ve got a box fan at home, give it a try!  The result will be delicious!

11 thoughts on “The Box-Fan Dehydrator Experiment

  1. Freedom35

    I stumbled on this post and I’m very interested in trying this. I also happen to be a big Alton Brown fan. Strangely enough I also just made arrangements to buy a dehydrator on Craigslist, so perhaps I saw this too late to.. If I happen to get my hands on a box fan it might be fun to try both side by side and see how the two methods compare.

    Do you know why your filter costs were so high? I noticed in the video it was stated that the filters should cost a dollar each, but you were up to $10 for all of them.

    1. The Vagabond Post author

      Hey Freedom35, thanks so much for commenting! I was at Home Depot already, and I hadn’t really done much research on whether I could do better on the filters– call it a case of Ready, Fire, Aim! I see that it’s possible to do a tiny bit better online with the filters, but not so much as to make a huge impact. I read that Walmart has them for $1, but I couldn’t find them online at that price, so perhaps they’ve gone up. I see a number in the $1-2 range on Google Shopping, but they’re fiberglass so we can’t use those.

      If it’s any consolation, I’ve used the same set three times now on fruit without much trouble. It would probably start to get gnarly fast if you’re making jerky, though.

  2. Ryan Lenz

    Hi–cool post, and I really liked your quantitative analysis part. I think the key with making cost-savers like this truly cost-saving is to be very careful about your timing. During harvest season, you can find incredible deals (even free!) on fruit and vegetables. Buying retail fruit and veggies is kind of missing the point–generally, economies of scale guarantee that your hourly rate is going to be pretty darn low, compared to what a commercial producer can do. Home-dehydrating is all about taking advantage of times of overabundance (or self-production), then letting the benefits slowly pay off as you avoid buying those products once the product is out of season. Anyway–just one man’s opinion–and thanks again for the post!

    1. The Vagabond Post author

      Thanks for the kind words, Ryan, and thanks for the comment! I would definitely love to be able to grow the fruit myself, but without a yard, we’re forced to rely on obscene produce deals at the market. You’re totally right, though, it’s critical to pick in-season and abundant product on a project like this. When it comes to meat, the markup is so high on commercially-produced jerky that simply waiting for a good sale at the market can save you a good amount.

    1. The Vagabond Post author

      It’s up to you to do what you consider safe, but I’ve done it with raw meat. I think it helps that you properly marinate it, though, as a lot of the acidic components of the marinade likely help to minimize bacteria, too.

  3. Michael A Crumpton

    In South Florida where the AC is running half the year at my house I was noticing the powerful blast of warm air coming out of the top of the compressor unit and was thinking this is at least 3 times as powerful as a box fan. I am going to try to mount a dehydrating screen a foot over the fan to see if it will dry fruit and vegies without obstructing the airflow too much. It is fairly humid outside, but if I can get it 75% dry on the AC and then transfer it to the oven for the last bit, it would be great, seeing as how the fan is running anyway. I am thinking some mosquito netting would probably enough of a filter, but I guess I will see.

  4. Wade

    That craft canvas (plastic) would be toxic as Hell for placing food right on it. I’ve just started researching how to make a dehydrator at home. I know for sure I’ll be using glass “plates”. I can get them at the thrift store for a buck or two each, the round, flat ones out of microwaves. It will require turning the food over but it also eliminates the toxins from plastic, silicone and parchment paper.

    1. Natasha

      Did that end up working for you? I would imagine you’d need something that allows airflow, otherwise the box fan is kind of pointless? Something like woven fibers, maybe bamboo.

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