What Size Box Spring for a King Mattress?

Essentially, a box spring acts as the foundation for your mattress while it is on the bed. It can also protect the mattress from dirt, absorb shock, prolong its life, and elevate it. However, the box spring will be useless if it is not the right size for your mattress. 

The Correct Size for a King-Sized Mattress

76″ wide by 80″ long box spring is the correct size for king-sized mattresses. However, some king-size box springs measure about  72″ wide by 84″ long and since this is the case, it would be best if you measure your box spring instead of the mattress considering that the box spring will be fitted to the frame of your bed.

Here are some tips to help you make the right choice.

Measure Your Mattress

Box springs usually come in the same size as mattresses so you can choose from king, queen, double, twin, or California king sizes. If you are not sure about your mattress fitting into your box spring, the best course of action would be to measure it.

In this case, we are looking at a king-size mattress that typically measures 76 inches by 80 inches so your box spring should have the same dimensions.

What Size Box Spring for a King Mattress

Plan for Your Anticipated Bed Height

Box springs add to the height of a bed. Therefore, you want to think about the height of your bed as well as the additional height that will be brought about by the bed spring. There are two common box spring heights  – a low profile 5-inch and a standard 9-inch.

Considering the popularity of high-profile luxurious mattresses and memory foam toppers, a 9-inch box spring is likely to make an extremely tall bed. As such, you want to go for a low-profile spring box if your mattress already has the desired height.

While a low-profile box spring is smaller, it does offer the same level of durability and support that a standard one does and it will not compromise the performance of your mattress either.

Choose Between a Standard and Split Box Spring

A standard box spring comes as a single unified piece while a split one features two sections that you can use to make up the dimensions of your mattress. Now, a box spring cannot be, manipulated or compressed to fit through doorways and narrow halls so if you have a king size bed, you may want to buy a split box spring.

Of course, a split box spring will cost you more,  but it is worth paying the price for the convenience you get when moving. Note that this kind of box spring will require extra support at the core so ensure that your box spring can accommodate that.

Pick a Box Spring that Fits Your Bed Frame

The last thing you want is for your mattress not to fit your box spring. So, if you have a rigid bed frame, check to confirm that the box spring can rest on top of it or slide in. Your bed frame also needs to be sturdy so that the box spring can fit in securely.

You may love to read: Indigo Sleep Mattress Reviews: Latest Insights and Facts


The right size box spring for a king mattress should measure 76 inches wide and 80 inches long. Nevertheless, you always want to measure the two to ensure that they make the perfect match otherwise you may have to spend more money making corrections.

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