---
title: "Foam vs Fiber Fill Cushion: Which Is Firmer for Stacking?"
url: "https://cushionguide.com/answers/foam-vs-fiber-fill-stacking-headboard/"
section: "The Cutting Table"
author: "Nate Kowalski, The Pattern Engineer of Detroit"
author_url: "https://cushionguide.com/masters/nate/"
published: "2026-02-23"
updated: "2026-09-24"
keywords: "foam vs fiber fill cushion, stacking floor cushions foam, headboard insert foam or fiber, French mattress cushion filling, firm cushion fill"
---

# Which is firmer for stacking cushions or a headboard: foam or fiber fill?

*Stack three pillows and you get a slope. Stack three foam blocks and you get furniture, partner. The difference is structural, not cosmetic.*

Also asked as: Foam filled or quilted?; I want to stack them on top of each other

> **The quick answer:** Foam is firmer than fiber fill: it makes a solid block that stacks and keeps its edges, which is why stacked Mah Jong-style floor cushions are foam-filled. Silicone fiber fill is softer and pillow-like, as in quilted French-mattress cushions. For a 60 in (152 cm) wide, 2 in (5 cm) deep headboard insert, fiber comes out very soft and foam firm.

![Purple velvet box cushion with self piping on a painted landing bench beside white stairs and a slatted balustrade](https://cushionguide.com/media/bench-cushions/purple-velvet-staircase-landing-bench-cushion-1600.webp "A purple velvet cushion with self piping turns a bench on the stair landing into a resting spot lit by a sconce and a small window.")

## Key facts

- Foam gives a firmer, more solid block than fiber fill, so it stacks better.
- Stacked modular floor cushions are foam-filled.
- A foam cushion is a high-density foam insert inside a zippered cover.
- A quilted French-mattress cushion is filled with silicone balls instead of foam.
- The workshop asks which filling you want before production starts.
- For a headboard insert, silicone fiber gives a very soft result and foam a firm one.
- Matching back cushions, such as 29 1/2 x 15 3/4 in (75 x 40 cm) for 29 1/2 x 29 1/2 in (75 x 75 cm) seats, can be made in the same fabric.

## Foam block vs fiber fill, line by line

|   | Foam insert | Silicone fiber fill |
|---|---|---|
| Feel | Firm, solid block | Soft, pillow-like |
| Stacking | [yes] Stacks well | Stacks less neatly |
| Build | High-density insert in a zippered cover | Silicone balls in a quilted French-mattress cover |
| Headboard insert | Firm | Very soft |
| Want it softer? | 28-density foam instead of 32, or a 3/4 in (2 cm) wadding layer | Already soft |

## Why a stack wants foam

A stack is a structure. Every cushion is the foundation for the one above it, so it has to hold its edges under load. A [high-density foam](https://cushionguide.com/glossary/#high-density-foam) block does; fiber moves toward wherever the weight isn't. Angles are just lengths in disguise, and a stack only stays square if its lengths stay put.

The quilted [French-mattress cushion](https://cushionguide.com/glossary/#french-mattress-cushion) earns its place elsewhere: a soft, lounging seat. The workshop asks which one you want before it cuts, so nothing gets decided by default. For the full comparison of fills, see [high-density foam vs memory foam, latex and fiber](https://cushionguide.com/guides/high-density-foam-vs-memory-foam-latex/); to dial in firmness, try the [foam firmness finder](https://cushionguide.com/studio/foam-firmness-finder/). Inserts on their own are under [foam inserts](https://cushionguide.com/cushions/foam-inserts/).

How many cushions high is your stack going to be?

## Specifying a headboard insert

1. **Measure the cover's inside**: Width and depth. One queen headboard cover called for 60 in (152 cm) wide and 2 in (5 cm) deep.
2. **Pick the feel**: Foam for a firm board, silicone fiber for a very soft one.
3. **Ask about natural fill**: None was offered for that headboard, though seats, backrests and pillows have been cotton-filled on custom orders.
4. **Confirm before production**: The workshop asks which filling you want before it starts.

> **Tailor's margin:** Stacked floor cushions are foam-filled for a reason: a foam block stays square under the next cushion, while fiber fill rounds into a pillow.

> A 60 in wide, 2 in deep headboard insert filled with silicone fiber comes out very soft; the same insert in foam comes out firm.
>
> — Nate

## Buyer questions

**A common question:** What's the difference between a foam cushion and the quilted French mattress style?

**The workshop's answer:** The foam version is a high-density foam insert inside a zippered cover. The quilted French-mattress style is filled with silicone balls. The workshop asks which you want before production begins.

**A common question:** For floor cushions I plan to stack, is foam better than pillow filling?

**The workshop's answer:** Both are made, but foam gives a firmer, more solid block that stacks well, which is why stacked modular sets are foam. Matching backs, such as 29 1/2 x 15 3/4 in (75 x 40 cm) for 29 1/2 in (75 cm) square seats, come in the same fabric.

**A common question:** Can you fill a queen headboard cover, 60 in wide and 2 in deep, with something natural?

**The workshop's answer:** The insert can be silicone fiber, which is very soft, or foam, for a firm result. A natural filler wasn't offered for that headboard.

**A common question:** Can I get something plusher than your firm foam?

**The workshop's answer:** Yes. Ask for 28-density foam instead of the standard 32 for a slightly sink-in feel, or add a 3/4 in (2 cm) wadding layer.

## Questions buyers ask next

### How dense is the standard cushion foam in US units?

The standard 32 kg/m³ foam is about 2.0 lb/ft³, above the usual 1.8 lb/ft³ high-density threshold. It's high-resilience cold foam at roughly ILD 42, firm enough that adults don't sink through, though no official ILD certificate is issued.

### Can a cushion be filled with cotton instead of polyester fiber?

Yes, through a custom order: seat cushions, backrests and pillows can be cotton or organic-cotton filled. Natural fibers cost a little more, and the quote shows the difference. Flax or linen stuffing isn't offered.

### Can I pair a firm foam seat with a softer back?

Yes. Foam backs hold their shape and stay put when wedge-shaped; pillow-style backs are softer and more relaxed. A firm foam seat with a softer filled back is an option the workshop offers.

## Related at the atelier

- [Is your cushion foam certified, and can I see the paperwork?](https://cushionguide.com/answers/cushion-foam-oeko-tex-certipur-certified/): The workshop does not claim a US foam-industry certification for its cushion foam; what it documents is fabric from OEKO-TEX Standard 100 certified mills, with certificates shared on request.
- [What is 32 kg/m³ foam in lb/ft³, and what's its ILD?](https://cushionguide.com/answers/32-kg-m3-foam-lb-ft3-ild-rating/): 32 kg/m³ foam is about 2.0 lb/ft³, so it clears the common 1.8 lb/ft³ high-density requirement.
- [Is your foam firm enough that it won't sag or flatten with daily use?](https://cushionguide.com/answers/high-density-cushion-foam-sag-flatten/): Yes: the standard foam is about 2.0 lb/ft³ (32 kg/m³) high-density, high-resilience foam with a medium-hard feel, and it keeps its shape for years without sagging or flattening.
- [Custom Bench Cushion in Speckled Navy Bouclé on Sage Walls](https://cushionguide.com/readings/speckled-navy-bench-cushion-sage-green-sash-window/): A dark speckled bouclé bench cushion suits a sunny window bench because cream flecks hide crumbs and fading better than a solid.
- [Velvet Bench Cushion Anatomy: Eight Colors, One Straight Gusset](https://cushionguide.com/readings/velvet-box-cushion-color-stack-sewing-workroom/): A velvet bench cushion is a box: top and bottom panels, an upright side gusset, piping at both seams, and foam cut to the cover's exact depth so the gusset stands without ripples.
- [Custom Bench Cushion in Dusty Mauve for a Library Reading Nook](https://cushionguide.com/readings/dusty-mauve-library-bench-cushion-built-in-shelves/): Take a bench cushion color from something already in the room and it will look planned.
- [Box edge, knife edge, bullnose: cushion edge styles explained](https://cushionguide.com/guides/box-edge-vs-knife-edge-cushion/)
- [A 1-to-10 cushion firmness scale for how your family actually sits](https://cushionguide.com/guides/cushion-firmness-scale-1-to-10/)

*± 1/4 in — Nate*

---

Written by Nate Kowalski (https://cushionguide.com/masters/nate/) for CushionGuide (https://cushionguide.com/about/). The site explains made-to-measure cushions and the partner workshop makes them; measurements are in inches first. This Markdown mirrors the page at https://cushionguide.com/answers/foam-vs-fiber-fill-stacking-headboard/