Own a Piece of Computing History with a Mechanical Calculator

For thousands of years, people have been working to automate mathematical computations. Mechanical calculators date back to the 17th century. While you may not find the first mechanical calculator on eBay, you can find many models dating from 1900 to 1960, which is the period that many people consider to be the heyday of mechanical calculators.

What are the most common types of mechanical calculators?

If you want a conversation piece and a connection to computing's past, a mechanical calculator is a great place to start. When looking for a mechanical calculator for sale on eBay, watch for several common types, some of which include the following:

  • Add-lister: These models have a crank that must be pulled to add the numbers. They could have 10 sets of numbers or just one.
  • Comptometer: This is a faster, key-driven machine that calculates automatically and does not have a crank. The keys usually have two numbers on them: one for adding, and a smaller one for subtracting.
  • Electromechanical: These use electricity to work the mechanics. Starting in the 1950s, manufacturers added electricity to make the machines faster.
  • Stepped Gear: These use accumulating gears to add and subtract.

What are some common brand names of mechanical calculators?

You can often find reasonably priced eBay items with the names of mechanical calculator pioneers. Look for these brands:

  • Facit: These pinwheel calculators were made in Sweden. Facit calculators come in several styles from the years 1918-1970.
  • Curta: Many consider these to be the first handheld calculator. Curta mechanical calculators for sale come in different types, but all share the same cylindrical shape.
  • Burroughs: Founded in 1892, the Burroughs Adding Machine company made many models of mechanical calculators into the 1970s.
  • Monroe: This major producer of mechanical calculators is still in business.

How can you evaluate a mechanical calculator before buying?

When you're looking at a mechanical calculator on eBay, look carefully at the following factors to help you decide which one to buy.

  • Age: Use the materials (metal or plastic) and the color (black models are probably older) to determine the age.
  • Condition: Read descriptions carefully to determine if a calculator is in working condition. Choose one that is working or can be repaired easily and has all its parts.
  • Manuals: Manuals for these old calculators are quite rare, so watch for these in listings.
  • Price: Research completed auctions to make sure you are paying a fair price for your purchase.