Most freestanding microwaves feature a plate or disc known as the glass turntable. It’s responsible for turning the food so that it’s equally exposed to microwave radiation on all sides. The whole thing is composed of the glass plate, turning wheels, and a turning mechanism included with the microwave.
With that said, do you know how to measure microwave plate size? For the most part, the measurement (in diameter) is provided by the specs, but do you know how to measure the plate just in case?
How Do You Measure a Microwave Plate Size?
You can get the diameter of the microwave plate and compare it to the measurement provided by the specs of the make and model of your microwave care of a measuring tape or sufficiently long ruler. Take note that the accuracy of the measuring stick or tape varies from product to product.
You can also compare the plate size relative to the size of your china plates. If it’s able to fit 10-inch to 12-inch plates then it’s likely to be a pretty big plate that’s at least around that size so that it’d have room to rotate.

Why Does the Turntable Disc or Plate Exist?
By the way, the turntable exists because if you don’t rotate the food while it’s being microwaved it’s like not turning your body when getting a tan at the beach. Parts of the food will remain cold while other parts get extremely hot. The cold parts are susceptible to bacterial spread, especially meat.
Aside from the microwave plate or turntable, there are also flatbed microwaves that instead make use of rotating antennas that bounce the waves all over the food instead of making the food rotate around stationary short-frequency radiowaves. This makes for a more even heating.
Further reading: What is a Microwave without a Turntable (A Flatbed Microwave)? Things To Consider Before Buying
What’s the Best Microwave Size for You?
The standard microwave size measures 47 to 48 inches in height (including backsplash), 26 to 28 inches deep, and about 30 inches wide. It varies from microwave to microwave or whether you’re getting a consumer-grade model or an outright commercial-grade one with extra inches and power.
As a rule of thumb, the power tends to match the capacity. If you have a 1-kilowatt microwave wattage then it’s usually (not always) paired up with a 1 cubic foot capacity for the microwave cavity. Smaller spaces require 20-inch wide spaces or up to 60-inches wide for designer kitchens.
A mini microwave, in contrast, tests the limits of a smaller kitchen inside an RV or trailer home by offering 700 watts of power and about 0.7 cubic feet of capacity.

How Do You Measure the Bottom of the Microwave?
The bottom of the microwave is tricky to measure because it rises and falls in order to accommodate the microwave plate or turntable disc along with the plastic turntable guide and its wheels. Take measurement of not only the depth but the indentation.
The turntable drive is in the middle of the ring and the turntable. It isn’t easy to get a clear view of the indentation for measurement when peering inside the microwave, so you’ll have to improvise and estimate at times or base it relative to the turning wheel and glass plate.
How Do You Replace a Microwave Turning Wheel or Turntable Guide?
It’s much easier to replace the turntable disc or glass plate than a turning wheel. Just buy a new one based on the make and model of your microwave or use measurements of the microwave interior to fit the right diameter of turntable for your device.
Now, you might need to get a measurement of your turntable to help fix the turntable guide or replace it. Otherwise, the disc will keep stopping and tilting whenever you use the microwave. Of course, you can always spare $20 to get a new guide, but you still need to know the size of the guide you need.
Making the Replacement Ring or Turning Wheel
To make a ring to hold the plastic rollers, you need to measure the bottom and decide the inner and outer diameters of the replacement ring. You need to figure out how much space is available so as to avoid undue binding between the glass turntable and the microwave bottom.
Cut a Circle from the ⅛-Inch Fiberboard
For example, let’s say the scribed circle for the roller is 10⅝ inches for the outer diameter. Cut the disc from your fiberboard to about 11½ inches in diameter then mark the center as precisely as possible. Scribe another circle of about 10⅝ inches on your 11½ inches disc then cut the excess out.
Mark Holes for the Rollers
Put up rectangular holes needed to insert the plastic rollers. Cut it in a way wherein the rollers rest on the edges of the old turntable guide or turning wheel. The holes should be placed on 120° radial lines. Drill two holes to remove the material needed to make the openings.
File Down the Holes to Make Them Smooth
Use a small file in order to clear and clean out the holes. File the rough edges down until all the excess material is gone but don’t overdo it or else the wheels won’t fit inside the holes. The plastic rollers should slide into the holes as comfortably as possible without extra space or play.
Keep the Rollers Vertical Inside the Holes
You need to lift off the turntable guide above the bottom of the microwave to allow it to turn. It also requires a bigger face that acts against the roller sliding in order to stay upright. Cut some rectangles from scrap fiberboard to glue unto the turntable.
One scrap will be above the new guide you’ve made while the other should be below it. It’s a primitive fix to keep the rollers vertical but it’s a serviceable solution.
The Final Verdict
There are many reasons why you’d need to know the size of your microwave plate, chief among them to see if they can fit the size of your 9-inch, 10-inch, 11-inch, or 12-inch serving plates. If the microwave is small, you’ll naturally need smaller saucers or plates to match.
It’s also possible that someone has donated an old microwave to your local NGO or church. The plastic frame of its turntable guide might be distorted after years of use, with the white rollers coming off the ends of their axles.
References:
- “Choosing a Microwave Oven that Best Fits Your Needs“, James core
- Phil B., “Microwave Turntable Guide–make a Replacement“, Instructables.com, Retrieved July 31, 2021