I can’t believe I did this. I ordered a foundation from Sleep EZ for my new latex mattress that is coming from Brooklyn Bedding.
However, I failed to measure the width of the space in between the boards on my old bed. It is 53 5/8, and Sleep EZ says the foundation is 54" Now I’m going to have to return it and find a narrower one. Strange that they make a foundation that is wider than the standard 53" box spring.
Anyway, just passing on this advice to everyone: measure carefully before buying anything!
cathye, I’d try putting the foundation on your bed boards and see if it fits before going through the trouble of returning it. Sometimes because of curves or whatever… 3/8" isn’t much.
Hi cathye,
The “standard” sizes for both mattresses and box springs can vary to some degree and there is really no consensus on what a standard size really is.
In the case of a full size foundation or box spring you will usually find them in a range between 53" and 54". Part of the reason for this is the slight differences between metric measurements and Imperial measurements.
A common box spring or foundation size is 137 CM x 191 CM which is approximately 54" x 75". Another common size is 135 cm x 190 cm which is approximately 53" x 75".
Singles are similar and can be found in both 38" and 39" width.
You can see the Serta “standard” size chart here which says that a full size is 53" x 74.5" +/- .5"
Their foundation here is 52.5" and their foundation for the iSeries here is 54"
The Sealy “standard” size chart here says that a full size is 53" x 74" +/- 1" and you can see here that their “standard” posturepedic foundation is 54"
The Simmons size chart (scroll down to the standard sizes question) says a full size is 52.5" x 74" and yet their Triton foundation here is 54" x 75"
There is a good multinational size chart in Wikipedia here (which lists 54") and another one with many unusual sizes here.
The "moral of this story is that there is no exact “standardization” unfortunately in either mattresses, box springs, foundations, or beds which means that your suggestion to measure first is always a good one 
Phoenix
Well, I found something on the Sleep EZ site that says it’s 53", so maybe the guy on the phone told me the wrong size. Keeping my fingers crossed! Thanks for the good info, Phoenix.