The best foam grade for a seat cushion depends on the cushion thickness, the type of seat, how often it is used and the feel required. A dining chair pad, a deep sofa cushion and a thin commercial bench should not automatically use the same foam.
For most everyday seating, medium, high firm and Reflex upholstery foams are the main choices. Very firm and reconstituted grades are useful where extra support, contract use or thin sections demand a denser construction.
A practical starting point
For most everyday seat cushions, compare High Firm, Reflex Medium and Reflex Firm. Medium Foam suits softer or lighter use, while Severe Very Firm and reconstituted foam are better for specific thin or contract applications. Cushion thickness and the support beneath it matter just as much as the foam grade.
Start with the finished cushion thickness
Thickness changes how a foam grade behaves. A foam that feels balanced at 4 inches may feel too firm at 1 inch because there is less depth available to compress.
Before choosing a grade, measure:
- finished width and length
- required foam thickness
- cover seam allowance
- any taper or rounded edge
- the internal size of the furniture frame
Use the foam sheet thickness guide if you are replacing an existing cushion or changing the depth.
Medium foam for general purpose cushions
Medium Foam Sheet is a versatile open cell polyurethane foam. It suits a wide range of general padding and lighter seating uses where a balanced feel is required.
Consider medium foam for:
- occasional chairs
- back cushions
- lighter use bench pads
- craft and padding projects
- seating where a softer response is preferred
For heavily used seats or thinner cushions, a firmer grade may hold the user more effectively.
High firm foam for supportive seating
High Firm Foam Sheet is designed for seating and applications that need extra firmness.
It is a common starting point for:
- dining chair pads
- sofa seat replacements
- window seats
- bench cushions
- caravan seating
- firm upholstery repairs
The finished feel still depends on thickness and the support underneath. A firm foam over a hard timber board will feel different from the same foam over webbing or springs.
Reflex Medium for responsive comfort
Reflex Pink Medium Foam has a resilient, quicker recovery response. It is slightly softer than Reflex Firm and is suitable for seating and mattress applications.
It can suit customers who want:
- a responsive cushion
- quicker recovery after use
- a premium upholstery grade
- a medium rather than high firm feel
Reflex foam should be selected for its response and intended use, not simply because the word branded sounds more suitable.
Reflex Firm for firmer responsive seating
Reflex Grey Firm Foam gives a firmer, resilient feel than Reflex Medium.
It is useful for:
- supportive sofa seats
- frequently used bench cushions
- firmer dining or office seating
- cushions where quick recovery is important
Choose the grade with the finished cushion and user in mind. A very light person may experience the same cushion as firmer than a heavier person.
Severe Very Firm for thin or specialist seats
Severe Very Firm Foam is intended for applications where extra firmness is required, particularly thinner seat cushions around 2 or 3 inches.
It is not the automatic choice for every sofa. In a deep cushion, the result may feel much harder than intended. Use it when the design genuinely needs a very firm support layer.
Reconstituted foam for dense support
Reconstituted foam is made from bonded foam fragments. It has a mixed colour appearance and a dense, firm character.
The 6lb grade is suitable for contract seating and cost effective firm support. The 9lb grade is very dense and is more appropriate for industrial matting, protective uses, gym mats and specialist commercial seating.
Reconstituted foam is not chosen for a soft, luxurious sofa feel. Its strength is dense support and durability in suitable applications.
What about average soft or cot safe foam?
Soft grades have useful purposes, but not every soft foam is suitable for a seat base.
Average Soft Foam can suit soft padding, back cushions and light use applications. Cot Safe Foam is described for nursery mattresses, headboards, crafts and costumes and is not suitable for seating.
Always check the stated best use on the foam sheets page. Colour alone does not identify a grade or prove that it is suitable for furniture.
Does density equal firmness?
No. Density measures the mass of foam in a given volume. Firmness measures resistance to compression under a test.
A higher density foam may offer better material content and durability without always being the hardest. Use both the product description and technical data.
Read foam density vs firmness before comparing grades from numbers alone.
Check the support under the cushion
The furniture base affects comfort and lifespan.
Common supports include:
- solid timber or board
- webbing
- metal springs
- slats
- mesh
A rigid board makes the cushion feel firmer. Worn webbing can make even a good foam feel unsupportive. Repair the furniture base before replacing the cushion if it has failed.
Consider a layered cushion
Some cushions use more than one foam grade. A firmer base can be combined with a softer upper layer when the cover and construction allow it.
Layering should have a clear purpose. A thin soft sheet over a firm base changes the first contact feel, but it does not turn an unsuitable support foam into a good seat.
For simple rectangular replacement cushions, one correctly selected upholstery grade is often easier to fit and maintain.
Measure the cover carefully
Old foam can shrink, crumble or take a permanent set. Do not assume its current dimensions are the original dimensions.
Measure the inside of the cover and the furniture opening. Allow for the cover style and whether a slightly full fit is intended. A foam piece that is too large can distort seams, while one that is too small can leave loose fabric and moving edges.
Our how to measure foam guide covers replacement foam in more detail.
Fire information matters
Furniture grade applications need the correct foam and cover materials. Do not use packaging foam, acoustic foam or closed cell foam that is not fire retardant as a substitute for upholstery simply because it is the right size.
Review each product card and the relevant foam data sheet. For commercial or regulated applications, confirm the complete specification rather than relying on a general website statement.
Quick selection guide
For a broad starting point:
- Softer or lighter use cushion: Medium Foam
- Firm everyday seat: High Firm Foam
- Responsive medium seat: Reflex Medium
- Responsive firm seat: Reflex Firm
- Thin extra firm seat: Severe Very Firm
- Dense contract support: Reconstituted 6lb
- Industrial or specialist very dense use: Reconstituted 9lb
Use this as a starting point, then check the furniture design, finished cushion depth and any technical requirement before ordering.
Foam wrap, stockinette and covers
The finished cushion may include polyester wrap, stockinette or a fabric cover around the foam. These layers can soften edges, help the foam slide into the cover and change the first contact feel.
Do not add so much wrap that the cover is overfilled or seams are placed under excessive tension. If the original cushion used wrap, photograph and measure it before dismantling the cover.
When should seat foam be replaced?
Replace the foam when it remains compressed, crumbles, splits, smells damp or no longer supports the user evenly. A stretched cover can sometimes make good foam appear worn, so inspect both components.
If only one cushion has failed in a matched set, compare the age and feel of the others. Replacing one with a much firmer new grade can make the seating feel inconsistent.
Choosing foam for your seat cushions
For most seat cushions, start by comparing High Firm, Reflex Medium and Reflex Firm foam. Use the finished thickness, frequency of use and furniture base to choose between them. Medium foam suits softer or lighter duty work, while Severe Very Firm and reconstituted grades belong in more specific firm, thin or commercial applications.
Check the product description and data sheet, measure the cover accurately and repair any failed support beneath the cushion before ordering.