Australia
How Thick Should a Seat Cushion Be? A Foam Thickness Guide in mm
A quick guide to choosing the right foam thickness in mm for chairs, benches, window seats, lounges and daybeds.
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Quick answer: As a guide: 40 to 50 mm for dining chair and bar stool pads, 50 to 75 mm for kitchen benches, 50 to 100 mm for window seats, 100 to 150 mm for outdoor lounge seats and daybeds, and 125 mm or more for deep-seat lounges. Thicker is not always better: on a bench or window seat, too much foam raises the seat height and can make it uncomfortable.
Foam thickness is the decision that most changes how a cushion feels, and it is the one people most often guess. Too thin and you feel the frame; too thick and a bench becomes too high to sit on comfortably. Here is a practical guide in mm.
Thickness by use
| Where it goes | Typical thickness | Why |
|---|---|---|
| Dining chair and bar stool pads | 40 to 50 mm | Adds comfort without changing seat height much. |
| Kitchen benches and banquettes | 50 to 75 mm | Comfortable for a long meal and keeps the table height right. |
| Window seats | 50 to 100 mm | Thicker for lounging, thinner if the sill sits low. |
| Outdoor chairs and lounges | 100 to 150 mm | Fills the frame and supports longer sitting. |
| Daybeds and swing beds | 100 to 150 mm | Good for lying down without feeling like a mattress. |
| Deep-seat lounges | 125 to 200 mm | Plush, sink-in comfort for generous frames. |
Check the seat height
Before choosing, measure from the floor to the top of the seat base, then add the foam thickness. A comfortable dining or bench seat usually finishes around 450 to 480 mm from the floor. If the result is much higher, choose thinner foam.
Thickness isn't the only factor
- Firmness: a thinner, firmer foam can feel more supportive than a thick soft one.
- Wrap: a polyester fibre wrap softens the edges and fills the cover for a fuller look.
- Indoor or outdoor: for uncovered outdoor seating, quick-dry foam drains water and dries quickly, which helps prevent mould.
Foam for Australian orders is made in Australia by our foam partner. You can buy foam on its own, a cover on its own, or a complete cushion: see custom cut foam and covers and replacement foam.
Foam types and how they feel
- High-density foam: a firm, supportive seat foam for everyday indoor seats.
- Super Soft foam: for back cushions only; it is too soft for seats.
- Dryfast (quick-dry) foam: open-cell foam for uncovered outdoor and boat seats. See Dryfast foam.
- Dacron wrap: adds about 6 mm and gives a rounder edge.
How thick can you go?
Our online builder takes most cushions up to 203 mm thick. Double chaise and daybed cushions can go up to 305 mm. If you need something thicker, email us for a quote.
Worked example: a kitchen bench
Say your bench base is 410 mm from the floor. A 50 mm cushion finishes at 460 mm, which sits comfortably at a standard table. A 100 mm cushion would finish at 510 mm, too high for most tables. So choose 50–75 mm.
Mistakes to avoid
- Matching the old cushion's thickness after it has compressed.
- Choosing back-cushion foam for a seat.
- Forgetting that piping and a wrap add a little height.
- Going thick on a window seat with a low sill, which can block the window.
Accuracy and delivery
We cut every cushion within ±13 mm of your measurements. If your foam arrives vacuum-packed, give it 12–18 hours to expand to full thickness before you judge the feel. GST is handled for you. For daybeds, see our outdoor daybed cushion guide, and for window seats, our window seat guide.
Thickness for back cushions
Back cushions are usually 75–150 mm and softer than the seat. On a deep outdoor lounge, thicker backs bring the seat depth forward so shorter people can sit back comfortably.
Next step
Measure your seat with our mm measuring guide, then build your cushion on the custom cushions page. Shipping is free anywhere in Australia, and prices are shown in AUD.
Frequently asked questions
What is the standard thickness for a seat cushion?
Most seat cushions are 75 to 125 mm thick. Dining chair pads are thinner, at 40 to 50 mm, and deep-seat lounges can go up to 200 mm.
Is thicker foam more comfortable?
Not always. Thick foam raises the seat height, and a firmer, thinner foam often feels more supportive.
What thickness is best for a window seat?
50 to 100 mm, depending on how high the sill sits and whether you want to lounge on it.
Which foam is best for outdoor cushions?
Quick-dry foam for uncovered areas, because it drains water and dries quickly. Standard high-density foam suits covered areas.
Where is your foam made for Australian orders?
Foam for Australian orders is made in Australia by our foam partner.
