On a hot day, there’s nothing quite like dropping some change into a vending machine and listening as a cold drink makes its way to the exit chute. It’s hard for most of us to imagine a time when we couldn’t get a cold drink or a snack — or even rent a movie — from a conveniently-located machine.

There are an incredible variety of vending machines around the world today. In return for payment in the form of coins, bills or credit, vending machines dispense everything from drinks and snacks to newspapers and DVDs. Some of the more interesting vending machines you’re likely to find dispense such things as electronics, live fishing bait, French fries, cars and blue jeans.

The first vending machine ever might have been Hero of Alexandria’s first-century machine that dispensed holy water when a coin was deposited. Vending machines didn’t become popular until the early 1880s when the first coin-operated postcard vending machines debuted in London, England. The first United States vending machine sold gum on New York City train platforms starting in 1888.

Long ago, you often needed to have exact change to use a vending machine. Today, though, vending machines accept coins, paper money and even credit cards. They can also give back change in the form of coins and bills.

How did vending machines get to be so smart? How can a machine tell a quarter from a dime? How does it know the difference between a five-dollar bill and a one-dollar bill?

Vending machines that accept paper money do things that most human beings could not do. They recognize bills based upon multiple observations of different features.

For example, many vending machines that accept bills first identify bills based upon optical scanning. Tiny photocells or miniature digital cameras use images of the inserted bill to “look” for tell-tale patterns that identify each particular bill.

Of course, it’s possible to print a picture of a bill that looks just like an actual bill. Luckily for vending machine makers, actual currency has safety features that they can use to verify that real currency has been inserted.

For example, one-dollar bills contain fluorescent ink that glows when an ultraviolet light shines on it. Some vending machines use ultraviolet scanners to measure the glow from a bill to verify it is real.

Real currency bills are also printed using magnetic ink. Many vending machines also use a magnetic reader to detect the magnetic signature of a bill to ensure it’s real and determine its denomination.

Still other vending machines have devices that measure bills to make sure they are exactly the right size. Some may also pass a small electric current through a bill to verify it is real. Because of the various safety features in currency, each denomination has a slightly different conductivity.

Coins are identified and verified mainly based upon their physical properties. Although some machines may have advanced technology that allows them to determine the chemical composition of coins, most vending machines simply compare physical characteristics of coins, such as their diameter, thickness and the number of ridges on the edge.

For example, a vending machine can recognize a quarter, because it is 0.955 inches in diameter, 0.069 inches thick and has 119 ridges along its outer edge. This is different from a dime, which is 0.705 inches in diameter, 0.053 inches thick and has 118 ridges.

Did you have any idea vending machines were that smart? Believe it or not, they’re actually getting smarter all the time. Many of today’s vending machines can be connected to the Internet wirelessly so they can transmit data to their owners. This can help the owners know which items have been sold and need to be restocked.

Some vending machines can also accept orders without being touched. Some touchless vending machines use motion recognition devices to interpret hand signals that users make to indicate what products they want. Still other vending machines allow users to purchase products by sending text messages from their mobile phones!

82 Join the Discussion

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    • Well, we think YOU are super cool for visiting Wonderopolis today and letting us know what you thought about today’s Wonder, Johnathan! Way to go! :-)

    • We like the Hot Brown Wonder, too, Reagan! But, we’re kind of partial, because we love ALL the Wonders of the Day! We like learning new things! :-)

  1. Hello, wonderopolis. I loved your video about vending machines. My favorite part was when it said that there is underwear vending machines. lol

    • It’s really amazing that you can purchase so many different types of things in vending machines, isn’t it, Katie? We think it’s awesome that you can even buy a CAR! :-)

    • We WONDER that too, Caroline! We like learning all kinds of things in Wonderopolis, and we REALLY like the surprise of seeing a new, FUN Wonder each day!

  2. Hello Wonderopolis! Thank you for today’s Wonder! I learned a lot. I didn’t know that vending machines have ultraviolet scanners to detect if the money is real. I think it’s cool that they can dispense electronic devices! The video answered my question about whether the cars vending machines dispense are full size. I can’t believe they are! Now I know that vending machines are smart.

    • What a GREAT comment, Boo the Turtle! Thank you for sharing all the cool things you learned by exploring today’s Wonder of the Day®! :-)

    • Thanks so much for sharing your thoughts about unicorns, Dominique! We think it’s GREAT that you visited Wonderopolis today! :-)

    • Hi, Abby! Thanks for sharing your favorite items from vending machines! We hope you’re careful about drinking too many energy drinks or other caffeinated sodas…we worry about our Wonder Friends! You can visit past Wonder of the Day® #426 – How Can You Recharge Your Batteries? to learn some other ways to energize yourself! Here is a link that will take you right to it: http://wonderopolis.org/wonder/how-can-you-recharge-your-batteries/. Happy WONDERing! :-)

  3. I didn’t know that vending machines were known since 1880. I loved this wonder today. Thank you for telling me about vending machines. You taught me a lot about vending machines. Vending machines you get your snacks from. How did you find this wonder? You’re cool doing all this stuff on wonderopolis.

    • Thanks for the really nice things you said about Wonderopolis and this Wonder of the Day®, Caleb! We’re glad you learned some cool new things about vending machines today! :-)


    • We’re glad you stopped by this Wonder and left us a comment, Wonder Friend! Thanks for sharing your thoughts about vending machines today! :-)

    • Hello, Mrs. Ploof’s 2nd Grade! We’re glad to count you all as new Wonder Friends! Thank you for letting us know you enjoy exploring Wonderopolis together! :-)

  5. I love this wonder today because vending machines give you energy. To not make you sick. I like the video because she teaches us about vending machines. I like that she said there are vending machines in Japan.

    • We liked learning about all the cool kinds of vending machines, too, Taylor! It’s really interesting that you can buy almost anything you would ever want from a vending machine now! :-)

    • That’s a pretty neat fact, isn’t it, Kevin? We think it would be neat if they had a whole mall of vending machines! :-)

    • We think that’s a really GREAT guess, Gareth! We can’t wait to visit Wonderopolis tomorrow to see if you are correct! :-)

  6. Vending machines were from a long ago.
    And I wonder about the vending machines was long ago. That is what. I liked the video because there are lots of vending machines.

  7. Hi, this is our first blog onto Wonderopolis. We were very excited to learn that the vending machines had magnetic readers to determine whether a bill was real or not. We still wonder how they have the smart cars in vending machines. How do they get them in and out? How many cars come in a vending machine and where would you find a vending machine like this? We think the next wonder topic will be about Unicorns because some people think they are real and unexplained. Thank you from Mrs. Loganbill’s class

    • We’re so glad you left us this AWESOME comment, Mrs. Loganbill’s class! Thank you for visiting Wonderopolis and letting us know what you learned by exploring this Wonder of the Day® together! We WONDER about that smart car vending machine, too! We WONDER who might have enough money to buy one in that way (instead of going to a car dealership), or if maybe that type of vending machine was just a super clever form of advertising? :-)

    • Hi, Alleycat! A future Wonder of the Day® about the Boston Tea Party is a GREAT idea…thank you for suggesting it! We hope you had fun learning about vending machines by visiting THIS Wonder! :-)

  8. I would like to get an iPod from there. I wonder how much they cost out of the vending machine more than at like, the stores. They cost like $100 bucks! And great wonder! :)

    • Thanks for letting us know you liked this Wonder, Ava! We have had Wonder Friends tell us that they have seen those iPod and iPad vending machines at airports when they travel. We think it would be cool to find out what other electronics people can purchase from vending machines! :-)

  9. Here I am again. I was just wondering is this live people commenting at wonderopolis or is it machines? I also wanted to say I only have 1 or 2 energy drinks a month thanks for warning me, bye. ;)

    • Thanks for leaving us another GREAT comment, Abby! We are real people here in Wonderopolis! We appreciate every comment we receive from our Wonder Friends, because it lets us know what you guys think about the Wonders of the Day and Wonderopolis over all! We especially like when our Wonder Friends share stories or personal connections to that day’s Wonder! :-)


  11. Hi wonderpoplis ,
    I learned that in Japan, they have big vending machines. You can do grocery shopping in them. I also learned that at church, you put a quarter and out comes water. I also learned you can buy iPods at an airport. I was thinking that I could make a wonder vending machine. It is where you put wonders in the machine, the wonder will have a number, you will push the number and out comes the wonder and facts will be on the back. How did you come up with how smart vending machine are? Love, Allison

    • WOW, WOW, WOW, Allison! We really LOVE your creative thinking about the Wonder vending machine! We think that would be really cool! Thanks for sharing your idea with everyone in Wonderopolis today! :-)

  12. I liked this wonder because I like learning. The wonder is really interesting. I also like Japan. Can there be some wonders about Japan and China?

    • We’re super glad you learned something new by exploring this Wonder of the Day®, Michael! We thought it was really neat to learn what vending machines really “know,” too! :-)

    • Your comment makes us super happy, Simone! We really appreciate that you like visiting Wonderopolis every morning! YOU ROCK! :-)

  13. Hi, I’m Mukund from Mrs. Caplin’s class. I learned that a quarter is 0.955 inches in diameter, 0.069 inches thick, and a quarter has 119 ridges along its outer edge. I also learned that some vending machines use ultraviolet scanners to make sure that dollar bills are real. Sometimes when I want to buy something out of a vending machine, I put the money in but I don’t get what I want out. I was really surprised when I read that vending machines could hold cars, electronics, and blue jeans. I learned that some vending machines can accept orders without being touched. I really liked this wonder.

    • We really liked learning those cool things about vending machines, too, Mukund! We have also put money into a vending machine and had something different than what we picked drop down or, even worse, we didn’t get anything at all! :-( We think lots of other Wonder Friends have experienced that, as well. THANK YOU so much for visiting Wonderopolis on your spring break…you are a true Wonder Friend! :-)

  14. Cool! I had no idea that ink from a dollar bill glowed under an ultraviolet light! Or the diameter of a quarter! When were the motion sensing vending machines invented? And the ones that reply to your text messages? I used a bit of background knowledge to figure out what “ultraviolet” meant. This wonder was phenomenal (Yes! I spelled phenomenal right on my first try!) and I learned many new facts, such as: a Greek hero built a water dispenser that took coins and gave water in return, vending machines were not very popular until the 1880’s when the first coin operated postcard machine was built, and that today vending machines sell a wide variety of things starting from cars to live bait, from iPads to bubble gum. Wow! Vending machines sell everything! Thank you for this wonderful wonder of the day!

    • Ryan,

      We’re so glad you enjoyed the Wonder about vending machines! Thanks for sharing your knowledge with us. It’s WONDERFUL that you explored vending machines and learned so much about them on your own! It’s safe to say motion sensing and text message vending machines are MUCH younger than the Greek water dispenser! :)

      Have you seen the cupcake vending machines? They are pretty neat. You choose from options on a touch screen computer, and the machine makes your cupcake!

      Thanks for being a great Wonder Friend, Ryan! :)

  15. Hello Wonderopolis,
    I thought today’s wonder of the day was cool. If things stay on their current path, we will have a whole self served mall! Not good, not bad. Many people work at malls and banks. If self service becomes the new silly band, then many people will lose jobs and America’s economy is already in trouble. On the other side, I think it’s so sweet that you can mix and match your own Coca Cola products. What about vending machines vending iPods? I’m planning on getting an iPod at the end of the year, maybe that’s where I’ll get them from. 0_o

    • Hello, Team McNeil 1! We tried one of those “mix and match” soda fountains in Wonderopolis the other day…it was so much FUN and our soda creation was WONDERful! Thank you for sharing your thoughts about vending machines today! :-)

    • Did you know that corn is already available in vending machines around the world, “Corn is Good?” You can purchase popCORN, CORN chips and even warm CORN soup from vending machines! We don’t think that’s CORNY at all…we think that’s WONDERful! :-)

    • Thanks for letting us know you liked the video for this Wonder of the Day®, James! We appreciate hearing from you today! :-)

  16. I like vending machines and once I tied a quarter to a string and put it in for a soda and when the soda came out I pulled the quarter back out.

    • What a WONDERful question, Audrey!

      According to the Wonder, “most vending machines simply compare physical characteristics of coins, such as their diameter, thickness and the number of ridges on the edge.”

      Vending machines sure are smart! Thanks for WONDERing with us today, Audrey! :-)

    • Sorry, about that Wonder Friend. We must have missed your comment. Would you mind resubmitting it for us? Thanks, for WONDERing with us, Hawa! :-)

    • Hi, WonderWoman! We like the red or blue colored vending machines. Which color is your favorite? Thanks, for WONDERing with us! :-)

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Have you ever wondered…

  • How smart are vending machines?
  • What types of things are sold in vending machines?
  • What is optical scanning?

Wonder Gallery

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Try It Out

Did you have any clue vending machines had gotten so complex and technologically advanced? Keep learning more as you check out one or more of the following activities with a friend or family member:

  • Did you know that vending machines can also help you in math by teaching you how to count money? It’s true. Try this fun online Vending Machine game to practice counting change! You can also get some real change from your piggy bank or your parents to practice counting. In fact, that spare change might come in handy during the next activity.
  • Ask an adult to take you on a field trip to check out vending machines. Do you know of a location that has several vending machines? If not, you can often find them near areas where people tend to wait. You could try a local airport, train station, or hospital for starters. Find some vending machines and check them out up close. What items are offered for sale? Do any of the machines accept credit cards? Can you tell what kinds of technology the machines that accept bills use? Have fun checking out some vending machines. Don’t forget to reward yourself with a drink or snack!

Still Wondering

In Illuminations’ Coin Box student interactive, children learn how to count, collect, exchange and make change for coins.


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