Key takeaways
- Using the full chair width. Measure inside the arms, not across them.
- Ignoring the back cushion. On deep seating, the back cushion takes up 4–6 inches of seat depth. If you replace backs with thinner ones, the seat suddenly feels too deep.
- Mixing thicknesses across a sectional. A 4-inch cushion next to an older, compressed 5-inch one looks uneven. Replace a whole sofa or sectional at once.
- Ordering square for a tapered seat. Many deep seating chairs are 1–2 inches narrower at the back; a trapezoid cushion fits these better.
24 x 24 patio cushions are made for deep seating chairs, sofas and sectionals whose seat measures about 24 inches wide and 24 inches deep; if your chair is a standard dining or bistro chair, you almost certainly need 20 x 20 or 22 x 22 instead, because a cushion that is too large will buckle and slide.
The three sizes people search for most, 20, 22 and 24 inches, each belong to a different family of outdoor furniture. Knowing which one you own saves a return.
Which furniture each size fits
| Cushion size | Furniture type | Typical thickness | Typical seat height without cushion |
|---|---|---|---|
| 20 x 20 in | Dining chairs, bistro chairs, Adirondack seat pads | 2–3 in | 16–18 in |
| 22 x 22 in | Larger dining armchairs, rockers, smaller lounge chairs | 3–4 in | 14–17 in |
| 24 x 24 in | Deep seating club chairs, sectional pieces, sofa seats | 4–6 in | 12–15 in |
| 25 x 25 to 27 x 27 in | Oversized deep seating and modular lounge sets | 5–6 in | 11–14 in |
Deep seating frames sit low because the thick cushion brings you up to a normal sitting height. A 24 x 24 x 5 inch cushion on a 13-inch frame gives a seat height of about 17–18 inches once it compresses slightly, close to an indoor sofa.
Measure before you buy
Nominal sizes are rounded. A cushion sold as 24 x 24 can actually measure 23.5 x 23.5 inches, and chair frames vary just as much. Measure the frame, not the old cushion, since old cushions shrink and lose shape.
- Measure width between the inside of the arms at the front of the seat.
- Measure width at the back, where the seat meets the backrest.
- Measure depth from the front edge of the frame to the backrest.
- Note whether the front edge is straight or curved, and whether back corners are notched around posts.
Fit tolerance
| Cushion vs seat | Result |
|---|---|
| Cushion 0–0.5 in smaller | Ideal snug fit |
| Cushion 1–2 in smaller | Works with ties or straps; small visible gap |
| Cushion more than 2 in smaller | Slides forward; looks undersized |
| Cushion 0.5–1 in larger | Usually compresses in; slight bulge |
| Cushion more than 1 in larger | Buckles in the middle; uncomfortable |
So if your seat measures 23 x 23 inches, a 22 x 22 cushion is closer to a proper fit than a 24 x 24. If it measures 24.5 x 24, the 24 x 24 is right.
20 x 20 vs 22 x 22 vs 24 x 24 at a glance
20 x 20 inch
The standard for patio dining chairs. These are mostly seat pads 2–3 inches thick, with ties at the back corners. On a dining chair, a thicker cushion lifts you too high relative to a 28–30 inch table, so stay thin here.
22 x 22 inch
The in-between size. It fits many wide resin and wicker armchairs, rocking chairs and compact lounge chairs. Thickness usually runs 3–4 inches. This is the size most often bought by mistake for deep seating, where it leaves a 2-inch gap.
24 x 24 inch
Deep seating territory. Expect boxed edges, 4–6 inches of foam, often a zippered cover, and usually a matching back cushion. Back cushions for these chairs commonly measure about 24 x 20 to 24 x 22 inches. Sold as a set of seat and back, pricing typically runs $80–$250 per chair, depending on fabric and foam quality.
What makes a 24 x 24 cushion comfortable for years
| Feature | Budget | Mid-range | Premium |
|---|---|---|---|
| Fill | Polyester fiber or low-density foam | Fiber-wrapped foam, about 1.5–1.8 lb/ft³ density | High-resilience or reticulated quick-dry foam |
| Thickness | 3–4 in | 4–5 in | 5–6 in |
| Cover fabric | Printed polyester | Solution-dyed olefin or polyester blend | Solution-dyed acrylic |
| Zippered cover | Often no | Usually | Yes, often with replaceable cover |
| Expected life outdoors | 1–2 seasons | 3–4 seasons | 5+ seasons |
| Typical price per seat cushion | $30–$60 | $60–$120 | $120–$250+ |
Foam density is the number that predicts sagging. Low-density foam feels fine in the first summer and develops a seat-shaped dip by the second. If density is not listed, a firm cushion with a zipper that lets you see a solid foam block is a good sign.
Common sizing mistakes
- Using the full chair width. Measure inside the arms, not across them.
- Ignoring the back cushion. On deep seating, the back cushion takes up 4–6 inches of seat depth. If you replace backs with thinner ones, the seat suddenly feels too deep.
- Mixing thicknesses across a sectional. A 4-inch cushion next to an older, compressed 5-inch one looks uneven. Replace a whole sofa or sectional at once.
- Ordering square for a tapered seat. Many deep seating chairs are 1–2 inches narrower at the back; a trapezoid cushion fits these better.
Keeping cushions in shape
Deep seating cushions hold more water than thin seat pads, so drainage matters. Stand them on edge after rain, store them in a deck box during long wet stretches, and flip and rotate them every couple of weeks so the foam and fabric wear evenly. With zippered covers, wash covers on a gentle cycle and air dry them on the foam slightly damp so they stretch back into place.
Follow-up questions
Can I put a 24 x 24 cushion on a 22 inch chair?
Only if the chair has no arms and you accept a 1-inch overhang on each side. In an armchair, the extra 2 inches has nowhere to go and the cushion domes up in the middle. Buy 22 x 22 instead.
Do 24 x 24 cushions fit sectional corner pieces?
Often, but not always. Many corner seats are 26–30 inches square or have a notched back corner. Measure each sectional piece separately, since corner, armless and end pieces in the same set can differ by several inches.
Is a 6 inch cushion better than 4 inch for deep seating?
Six inches feels more like an indoor sofa and lasts longer before bottoming out, but it raises seat height by about 2 inches. On a low frame that is usually welcome; on a frame already 15 inches high, 4–5 inches keeps your feet flat on the ground.
Measure the frame, pick the size within half an inch, choose foam that will not sag, and 24 x 24 patio cushions will make a deep seating set feel like indoor furniture again.
