How To Make a Mattress Firmer if It’s Too Soft

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You spend one-third of your life in bed. Sleeping on a bed that doesn’t fit your comfort needs can be painful and leads to lifelong problems. It’s painful on your back, your shoulders, and can eat away at how many hours of sleep you get.

If your back pain usually goes away after you get up and move around for an hour or so, then your mattress is the crux of the problem. Back pain can be caused by sleeping on a mattress that is too soft and/or one that’s too firm. Before you go out and spend money on a new bed there are a few tricks that can help you get a few more years out of your current one.

The following information will guide you through these tricks and help you understand what the mattress industry calls “the comfort test.” Read on and you will find out just how to make a mattress firmer.

Traditional Mattresses

hand testing mattress firmness

Mattresses break in over time. If it’s is sagging in the middle and has adequate support underneath, that is a good indicator that its time for a new bed. This means the inner support system is breaking down. However, prior to going out and buying a new mattress, make sure to look into the warranty. Traditional innerspring beds like Sealy, Simmons, and Serta have stipulations for mattress replacement like sagging; it must be at or exceed one and a half inches. However, note that any stains void the warranty and many stains – no matter what they are – land in the zero-tolerance zone for a replacement.

It is always a good idea to protect it with a waterproof mattress pad, preferably one that carries the identical warranty as your mattress. Protect it with a waterproof mattress pad immediately after purchase. Regardless if it is sagging or not, there are a few ways you can make your mattress firmer.

Making It Firmer

traditional mattress on top of another

The very first step you should take to see if your mattress can get firmer is to place it on the floor. Traditional box springs have give or spring to them. They work like shocks for your car but are designed for your mattress. By placing it on the ground, you can easily identify if that change in the firmness works for you. If it does, you can mimic the floor by placing plywood on top of the box spring. This will dilute the spring that the box provides to your mattress. If your bedroom set allows for you to completely eliminate the box spring, replacing it with plywood will get an even firmer feel.

Be careful as this fix cannot be done on a standard metal frame. It needs to have supporting slats running from left to right under the plywood for two reasons:

  1. it will sag without them
  2. your warranty will be voided.

The great thing about this trick is that you can try it at home before you have to deal with getting plywood, measuring it out then running to the hardware store at least three times (three is the unspoken “rule” of do-it-yourself home projects after all).

Mattress Toppers

zipping a mattress cover

The mattress industry does offer mattress toppers that can assist you in making it firmer. These can be costly, especially if you have a king-size bed, but they can add life to it. Make sure you buy one with a return option because most places you are buying them from comes in the box off the shelf.

There aren’t many places that allow you to try them in the store, and even then, the real test is trying it on your mattress at home. Doubling up the last two tricks is an additional option to potentially enhance firmness. The combination of plywood under your bed plus a firm mattress topper can pay dividends if it’s is too soft, particularly if you have a pillow top mattress.

Foam Mattresses

Hand stamp on memory foam mattress

Not all beds have traditional innerspring. There is an entire industry of all foam beds made famous by Tempur-Pedic. The plywood trick stated above does not apply to Tempur-Pedic products because their box springs do not have any spring to them. They have the plywood trick already built in. It is critical to understand that all foam beds – especially memory foam – are sensitive to the temperature of your home. If you need to firm up your Tempurpedic, or any foam mattress, try setting the room temperature colder. This will harden the foam.

If you traditionally have the room temperature on the warmer side, the bed is already softer than normal. It goes both ways. Memory foam is the “top dog” of comfort layers. It’s pricey, comfortable, and lasts a long time. However, all memory foam, whether it is in a mattress topper, your mattress or is your mattress can be manipulated by the temperature of your home. For an all foam bed that needs to be firmer, you can enhance the impact by getting a firm pad and adjusting the temperature.

The best way to change the comfort of an all foam bed is to adjust the temperature of the room. Making the room cooler is easier because if you need to be warm and cuddly, you can just add more blankets. However, if you need it to be softer and can’t sleep in the heat, making the room warmer isn’t a viable option. In this case, finding a suitable mattress topper is your best bet because they come in all types of comfort and softness.

Making Foam Mattresses firmer

There tends to be a “set it and forget it” mentality when it comes to beds. You get it home, dress it up, and you go about your day. Over time you spend six to eight hours in the same spot on your bed and like footprints in the sand – your mattress will start to have body impressions.

Rotate and Flip method

lifting up mattress

That’s why it’s important to rotate it at least twice a year. The foot of your bed doesn’t support the same weight as the head of your mattress. By rotating it you are evening out the comfort layers and allowing it to break in evenly. This goes for both traditional and all foam mattresses.

Two-sided mattresses are a thing of the past. Most of the industry leaders moved away from making two-sided mattresses years ago but you might still have access to one. If you have a two-sided mattress it’s important to flip it as well as rotate it. Understandably life happens and remembering to rotate or flip it can fall off your radar.

Try rotating it concurrently with changing your smoke detector batteries during Daylight Savings time changes. If you are in Arizona (or another place that doesn’t acknowledge the absurd tradition of Daylight Savings time) set a calendar notification for every six months. Your mattress will thank you for this.

The Sagging Mattress

Sagging mattresses typically mean that it’s time for a new bed. There are four major ways you can correct the sagging without splurging:

  • the plywood trick
  • rotating the bed
  • replacing the box spring (more to follow)
  • purchase a firm mattress topper

These will help extend the life of your mattress. Unfortunately, if these tricks miss the mark, you may need to look into either purchasing a new bed or into the warranty of your current mattress.

Much like the spinal column in the human body, when it is sagging in the middle it means the support is starting to give out. That indicates that the most important part of your mattress is no longer functional. However, there is another solution.

Replace the Box Spring

hand holding spring

Box springs are vital to how your mattress feels. Over time box springs can lose their ability to support both you and the mattress. If so, sagging will be immediately evident as well as waking up with back pain. Fortunately, replacing the box spring on your mattress is relatively inexpensive compared to purchasing an entirely new set.

Another way to firm up the box spring is to use the plywood trick as stated earlier. Remember, both the mattress and the box spring work together. In order to have the best sleeping surface, the support underneath your bed needs to be strong and sturdy.


Hand pulling bed sheet

Bedding nowadays tends to be robust and glamorous. If you are trying to make it firmer, make sure to keep the top bedding of your bed sleek and tight. This means pulling the fitted sheet to mimic a wetsuit type fit (free of wrinkles and acting like a second layer of skin). Remember that mattress toppers add to the height of your bed. If you go with a firm mattress topper (or any topper), you may need to make sure you have deep-pocketed sheets to fit over it.

Water Weight

Did you know that beds can double even triple in their original weight? That’s due to the combination of condensation and sleeping on it night after night. Evaporation is another way to make your mattress firmer.

Carefully place it in the sun for a few hours and let nature do the work. This will harden the comfort layers that have been absorbing moisture every night. Think of it like a wet sponge – if you place a wet sponge out in the sun, it dries up and gets firmer. The same can be said about your mattress. An added bonus is this will also kill off unwanted bacteria.

Last Resort

woman sleeping on mattress

If nothing seems to work in your favour, the final step when it comes to trying to make your sagging mattress firmer, soft beds firmer, firm beds softer, or to even eliminate that nagging back pain is to purchase a new mattress either at the store or online.

They don’t last forever and if your mattress is long overdue for an upgrade, it might be a good time to consider purchasing a new mattress. Current technology in mattresses has been able to split hairs in comfort needs for all types of sleepers.

If it’s a firm bed you want, make sure you don’t get swept away into getting a pillow top with a firm layer. Stick to firm and medium because over time that pillow top will break in and you will be forced to re-evaluate your mattress situation all over again.

Also, be sure to purchase your mattress from a credible organization that offers a trial period. It takes time for your body to get used to it, and it takes time for it to break in. Remember that the bed you lay on in the store will not feel like the one you bring home. It takes time to acclimate to your body and the environment.

Wrapping it Up

You might be telling yourself that the mattress industry is as convoluted as their latex foam layers and you’d be right. But like any high price purchases – researching is key. The current mattress you have at home can be made firmer by several methods mentioned such as:

  • the plywood trick
  • getting a firm mattress topper
  • adjusting the temperature
  • rotating it regularly
  • placing it under the sun
  • keeping the bedding tight
  • replacing the box spring
  • purchasing a new mattress set.

It can be made softer by adding any number of mattress toppers available. If you are unsure of what comfort category works for you, step into a store and try them out. No matter what your situation is if your back, neck, shoulders or even your significant other is sore in the morning, pay attention to the signs your body is giving you.

It may seem like a lot of work to fix it but it will provide exponential value if it ends up giving you a few more years on your current mattress. Remember, spending six to eight hours a night out of alignment will really place a damper on your day, sleep, and your overall quality of life.

Rest assured, your comfort is worth the investment.

Additional Resources

Randall Sinkiewicz
Randall Sinkiewicz

Randall Sinkiewicz has nine years experience working in the mattress industry. He is currently a communications student at CSUG.

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