---
title: "Window Seat Back Cushion Height: Clear the Sill and the Lever"
url: "https://cushionguide.com/answers/back-cushion-height-under-window/"
section: "The Cutting Table"
author: "Harlan Pruitt, The Elder of High Point"
author_url: "https://cushionguide.com/masters/harlan/"
published: "2026-02-22"
updated: "2026-02-22"
keywords: "window seat back cushion height, back cushion under window, bench back cushion size, window bench backrest, low sill backrest"
---

# How tall should a back cushion be on a bench under a window?

*Let the window tell you, my friend. The sill and the latch settle the height before the tape measure ever comes out of the drawer.*

Also asked as: What depth and height would you recommend?; Keep guests from hitting the window lever.

> **The quick answer:** A back cushion on a bench under a window should stand taller than the window hardware and stay loose. With a lever about 11 in (28 cm) above the seat cushion, a back 14-16 in (36-41 cm) tall and 3-4 in (8-10 cm) thick keeps the lever safely behind it. Under a very low sill, a short flat back replaces the round bolster.

![Close-up of a black and cream geometric jacquard back cushion resting on a terracotta bouclé seat cushion by arched windows](https://cushionguide.com/media/backrest-cushions/geometric-backrest-terracotta-boucle-seat-closeup-1600.webp "Two fabrics, one seat: a crisp geometric back cushion lifts a warm terracotta bouclé base.")

## Key facts

- Back cushion height is set by the sill and the window hardware.
- With a lever about 11 in (28 cm) above the seat cushion, the back is 14-16 in (36-41 cm) tall.
- That back is 3-4 in (8-10 cm) thick.
- Back cushions stay loose so the window can still be opened.
- A 4 in (10 cm) floor cushion under an 11 in (28 cm) sill leaves 7 in (18 cm) for the back.
- A low flat back piece can replace the round bolster under a low sill.
- Matching backs are made in the same fabric as the seat.

## Measure these before you order the back

- ✓ From the top of the seat cushion up to the window lever or latch.
- ✓ From the floor or seat up to the bottom of the sill.
- ✓ How the window opens, since the back has to lift away for it.
- ✓ The seat cushion's thickness, because the back stands on it.

## Two windows, two answers

A buyer in the US had a bench against a windowsill with the lever about 11 in (28 cm) above the seat cushion, and wanted to keep people from knocking into it. The workshop's advice: a back 14-16 in (36-41 cm) tall, so the lever sits safely behind it, and 3-4 in (8-10 cm) thick, left loose so the window still opens.

Another buyer had a [floor cushion](https://cushionguide.com/cushions/floor-cushions/) under a sill only 11 in off the floor. The seat is 4 in (10 cm) thick, which leaves 7 in (18 cm), no room for a round [bolster](https://cushionguide.com/glossary/#bolster). So the workshop made a low flat back piece instead.

How high off your seat does the latch sit? Buy the cushion once, cry once. The [back cushion height Pattern](https://cushionguide.com/guides/back-cushion-height-sizing/) and the [backrest cushions](https://cushionguide.com/cushions/backrest-cushions/) page carry it further.

## Where backs under windows go wrong

- ✗ A back shorter than the lever, which leaves the hardware where shoulders land.
- ✗ A back fixed in place, when the window has to open.
- ✗ A round bolster squeezed under a sill with only 7 in (18 cm) to spare.

> **Tailor's margin:** If a window lever sits 11 in above the bench cushion, make the back cushion 14 to 16 in tall and keep it loose, so the window still opens.

> Under a sill 11 in off the floor, a 4 in floor cushion leaves 7 in for a back, so a low flat back piece takes the place of the round bolster.
>
> — Harlan

## Buyer questions

**A common question:** Do you make back cushions to match a bench cushion, and how tall should they be against a window?

**The workshop's answer:** Yes, in the same fabric so the set coordinates. With a window lever about 11 in above the seat cushion, the advice was 14-16 in tall, so the lever sits safely behind, and 3-4 in thick. The backs stay loose so the window can still be operated.

**A common question:** Can the backrest be short enough to fit under a low window sill?

**The workshop's answer:** Yes. The floor cushion is 4 in thick, so a sill 11 in off the floor leaves 7 in for the back. A low flat back piece is made instead of the round bolster.

**A common question:** French-style tufted cushion set: is a backrest included?

**The workshop's answer:** Yes: the set has the seat cushion, one backrest and two round armrest bolsters. The backrest is 16 in (40 cm) by 4 in (10 cm) and matches the seat length.

## Questions buyers ask next

### Should a back cushion under a window be fixed in place?

Not under a window you open. Loose backs lift away when you need the window, which is why the 14-16 in backs on one bench were left loose rather than attached.

### How thick should a window bench back cushion be?

The workshop advised 3-4 in (8-10 cm) for a bench under a window, paired with a 14-16 in (36-41 cm) height. Matching backs are made in the same fabric as the seat cushion.

### Do I measure the back height from the bench or from the seat cushion?

From the top of the seat cushion, since the back stands on it. The 11 in lever height in the workshop's example was measured above the seat cushion, not above the bench.

## Related at the atelier

- [How do I measure backrest height: from the top of the seat cushion or from the bench?](https://cushionguide.com/answers/how-to-measure-backrest-cushion-height/): Measure backrest height from the top of the seat cushion, so the backrest sits on the bottom cushion; the shop usually recommends this because it looks and fits better.
- [How can I attach a back cushion to the wall?](https://cushionguide.com/answers/attach-back-cushion-to-wall/): Attach a back cushion to the wall with hook-and-loop fastener: the workshop sews one side onto the back of the cushion, and you fix the matching strip to the wall with strong adhesive, or screws for…
- [Can I buy just the back cushion without the seat?](https://cushionguide.com/answers/buy-back-cushion-only-without-seat/): Yes, a back cushion can be ordered on its own, in any size and color, with no seat cushion attached.
- [How tall should a back cushion be? Sizing backrests to your seat](https://cushionguide.com/guides/back-cushion-height-sizing/): A standard back cushion is 16 in (40 cm) tall and 4 in (10 cm) thick, made the same length as the seat, with its height measured from the top of the seat cushion.
- [Outdoor Back Cushion Proportion: Amber on a Gray Patio Sofa](https://cushionguide.com/readings/amber-outdoor-back-cushion-gray-garden-sofa/): A patio back cushion should come close to the thickness of the seat cushion below it, because that proportion props the sitter upright the way the sofa was designed.
- [Back cushion filling compared: shredded foam, a solid wedge or fiber](https://cushionguide.com/guides/back-cushion-fill-shredded-foam-vs-wedge/): For most benches and banquettes, a shredded-foam back pillow over a firm foam seat is the right default: soft to lean on, yet it keeps its shape against a wall.
- [Replacement cushions for a nursery glider, piece by piece](https://cushionguide.com/guides/glider-rocker-replacement-cushions/)

*Sit well. — Harlan*

---

Written by Harlan Pruitt (https://cushionguide.com/masters/harlan/) 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/back-cushion-height-under-window/