How to Make a Potato Powered Calculator

Long a science-fair project staple, this potato powered calculator is easy to recreate yourself!


Up next in How to Do Fun Tech & Science Projects (52 videos)

School science fair coming up? Don't worry: We've got step-by-step instructions to dozens of science projects in this Howcast video series, including how to build an erupting volcano, how to make glow-in-the-dark art, how to make a weather barometer, how to make disappearing ink, how to make 3-D glasses, and how to make a marshmallow gun.


You Will Need

  • Two potatoes
  • A marker
  • Two pieces of heavy copper wire
  • Two galvanized nails
  • Three alligator clips with wires
  • A low-voltage, battery-operated calculator


  1. Step 1

    Number potatoes

    Label your potatoes one and two.

  2. Step 2

    Remove battery

    Remove the batteries from the calculator. Take care to note where the positive and negative terminals are within the battery compartment.

  3. Step 3

    Insert nails

    Insert a nail into each potato and stick a copper wire into each potato, opposite the nail.

  4. Alligator clips, nails, and wire can be purchased at your local hardware store.

  5. Step 4

    Connect clips

    Connect one alligator clip to the copper wire in potato no. 1 and attach the other end to the positive battery terminal in the calculator's compartment.

  6. Step 5

    Create second connection

    Clip a second alligator clip to the nail in potato no. 2, and then connect the other end to the calculator's negative battery connection.

  7. Step 6

    Complete circuit

    Complete the circuit by clipping the third alligator clip to the nail in potato one and to the copper wire in potato two. Voila, a working calculator!

  8. Did you know? Americans eat 130 pounds of potatoes per person each year.