How to Measure a Light Globe

How to Measure a Light Globe

Published by Light Bulb Surplus Staff on Aug 10th 2020

Remember the proverb measure twice and cut once? One should always double-check one's measurements for accuracy before cutting a piece of wood. This also holds true before ordering a replacement globe.  Even though globes are light, they cost a lot to ship because freight carriers charge for dimensional weight.  If you order the wrong size, it could end up costing more than the cost of the product.  The only one happy in that scenario is the freight company.  Here are some tips for making sure you get the right size lighting globe for your needs.

Supplies needed to measure the size of a light globe

  • Measuring tape or String (Use a ruler to measure the length of the string)
  • Globe you are replacing
  • Calculator (on most phones) or (you are just awesome at math)
  • Pencil or Pen

Identify what type base or opening you have 

4 Standard Globe Bases

  • Neckless
  • Neck Flange (Lip)
  • Twist & Lock
  • Screw Neck (Threaded)

Neckless Globes

Take a ruler and measure the "equator" or widest part of the globe's opening.  Don't forget to measure twice (wink wink) and take out your pencil and pen and record your measurement. Now you know your Neckless opening size.  Proceed below to determine your globe's diameter.

Neck Flange - Twist Lock - Screw Neck

You will need to take a ruler and "carefully" measure the outside diameter of the Neck Flange, Twist/Lock or Screw Neck base. This is the most outer part of the neck of the globe. Make note of the inner diameter as well.Take out your pencil and pen and record your measurement.

Measuring the Diameter

Caution: Remember to turn off the light and allow the globe to cool down if it was on.

Step 1.  Find a flat surface and set the old globe against a wall or hard surface.  

Step 2.  Take a box or a book (something straight) and put it on the other side of the globe.  

Step 3. Take your ruler and measure. You can take a pencil or chalk and mark the floor and measure it after you remove the globe or set the ruler and top and measure from there. Again, please measure twice.  Globes have variances of +/- of 5% due to the injection, blow molding and vacuum forming processes to manufacture round spheres.  Don't worry if your globe isn't exactly a round number, if it is within the 5% tolerances, you are most likely are safe. If the globe is shaped irregularly, measure the widest point in two directions perpendicular to each other and average the two measurements.

Step 4. Write down all your measurements.  Make sure the globe meets your specifications.  We will be happy to assist you.  Please contact us if you have any questions.

It's important to note that not all light globes are interchangeable, as they may have different base types or colors. Before purchasing a replacement globe, make sure to check the manufacturer's instructions or consult with a professional to ensure you select the correct one.