---
title: "How to measure a window seat cushion: five edges, one sketch"
url: "https://cushionguide.com/answers/how-to-measure-window-seat-cushion/"
section: "The Cutting Table"
author: "Nate Kowalski, The Pattern Engineer of Detroit"
author_url: "https://cushionguide.com/masters/nate/"
published: "2026-04-13"
updated: "2026-09-24"
keywords: "how to measure a window seat cushion, window seat cushion measurements, built-in bench cushion, measure bench for cushion, custom window seat cushion"
---

# How do I measure a window seat or built-in bench for a custom cushion?

*Measure the seat, not the room. Then draw what you measured, edge by edge.*

Also asked as: Just had a window seat built, unsure how to measure.; Measure inside or outside of the bench?

> **The quick answer:** To measure a window seat cushion, tape the seat top itself with a rigid tape: the front edge wall to wall, the back edge along the window, the depth on the left and right, and each angled side separately. Inside a bench frame, measure wood to wood. Send a top-view sketch with a photo so the workshop can confirm the shape.

![Amber and black leopard-print box cushion on a white bench with oak top, olive and black pillows, mustard curtain beside](https://cushionguide.com/media/bench-cushions/amber-leopard-bench-cushion-mustard-velvet-curtain-1600.webp "Classic leopard in golden amber, framed by mustard velvet and a snake plant for a warm, glamorous corner.")

## Key facts

- Measure the bench top, not the floor; the two can differ.
- Use a rigid tape on the seat surface.
- Take the front edge, back edge, depth on the left and right, and each angled side.
- The back edge along a window is often shorter than the front.
- Inside a bench frame, measure wood to wood, not the outside of the bench.
- Exact depth matters: 20 in (51 cm) is not 19¾ in (50 cm).
- Sizes are double-checked before shipping.

## Each measurement, where to take it, and the usual slip

| Measurement | Take it | Common slip |
|---|---|---|
| Front edge (length) | Wall to wall, straight, on the seat top | Measuring the floor below |
| Back edge | Along the window | Assuming it equals the front; it's often shorter |
| Depth (width) | Front to back, on the left and on the right | Rounding 20 in (51 cm) to 19¾ in (50 cm) |
| Angled sides | Each side edge on its own | Measuring one side and doubling it |
| Inside a frame | Inside, wood to wood | Using the bench's outer size |

## Why the seat top gets the tape

Built-ins aren't always square, partner. The floor line and the seat top can differ, and a window wall often pinches the back edge shorter than the front. So measure where the cushion will lie, with a rigid tape that won't sag.

Length means side to side; width means front to back, the seat depth. Draw a top view with each number on its edge and send it with a photo. Angled sides go through the [trapezoid cushion calculator](https://cushionguide.com/studio/trapezoid-cushion-calculator/) or the [bay window calculator](https://cushionguide.com/studio/bay-window-calculator/). The [window seat measuring Pattern](https://cushionguide.com/guides/how-to-measure-window-seat-cushion/) covers older homes, and finished shapes live under [window seat cushions](https://cushionguide.com/cushions/window-seat-cushions/). How does your back edge compare with the front?

## The three-sided bench and the laser

One buyer wrote in about an entryway bench enclosed on three sides, measured by laser at 24¼ x 76¾ in (61.7 x 195.1 cm). The workshop said to write 24¼ x 76¾ in (61.5 x 195 cm), a hair under the reading. Handmade cushions vary slightly, but not enough to cause fitting trouble here, and sizes are double-checked before shipping so a cushion never comes out larger than ordered. Elsewhere the rule stands: exact inside measurement, no deduction.

> **Tailor's margin:** Measure a window seat cushion on the seat top, not the floor: the two can differ, and 20 in of depth is not 19¾ in.

> For a cushion inside a bench frame, measure the inside from wood to wood and order those exact numbers, not the bench's outer size.
>
> — Nate

## Buyer questions

**A common question:** What's the right way to measure a window seat for a made-to-measure cushion?

**The workshop's answer:** Front edge wall to wall, back edge along the window, depth on both the left and right, and each side edge separately if the walls are angled. Use a rigid tape on the seat surface, sketch a top view with every number, and send it with a photo; the shop confirms the shape.

**A common question:** How should I send the numbers for a built-in bench?

**The workshop's answer:** Draw the seat on paper with every dimension and send it. Measure the bench top, not the floor, since they can differ, and be exact about depth: 20 in (51 cm) is not 19¾ in (50 cm).

**A common question:** Should I order the exact bench measurement or size down?

**The workshop's answer:** If the cushion sits inside a bench frame, measure the inside wood to wood and order those exact inside measurements, not the outer dimensions. The cushion is made to fit that inside space.

## Questions buyers ask next

### On a window seat cushion, which way is length and which is width?

Length runs side to side along the window; width is front to back, the seat depth. Write both on a top-view sketch so nothing gets swapped, and give the thickness separately.

### Will I see a drawing of my window seat cushion before it's cut?

Yes. The workshop sends a drawing of your dimensions and makes the cushion exactly to the approved layout. It builds strictly to your numbers and won't choose the final size for you.

### Where is depth measured on an angled window seat?

Straight from front to back at 90 degrees, at the deepest point, not along the angle. Length is the total between the outer corners. Then add the long edge, the short edge and each angled side.

## Related at the atelier

- [Window Seat Cushion in Black Velvet: Thickness vs Seat Height](https://cushionguide.com/readings/black-velvet-l-shaped-window-seat-cushion-column-step/): For a window seat cushion, finished seat height equals the bench top plus the cushion thickness, so choose the thickness last.
- [Trapezoid Window Seat Cushion in Rust for a Small Stair Landing](https://cushionguide.com/readings/rust-trapezoid-landing-window-seat-cushion/): A small landing window seat feels generous when the cushion fills the whole trapezoid, wall to wall, with no bare board at the angled ends.
- [Window Seat Cushion Edges: Box, Knife, Rounded or Clipped](https://cushionguide.com/readings/tobacco-brown-awning-stripe-window-seat/): Choose a box edge for a window seat cushion when you want it to look built in: a side band gives straight, upright sides, and a tall one shows off a stripe.
- [What if my window seat measurements don't add up because the corners aren't square?](https://cushionguide.com/answers/cushion-measurements-dont-add-up-not-square/): If your window seat measurements don't add up, nothing is cut: the workshop draws the cushion to scale, checks that the shape closes, and asks you to re-measure named edges, measure both diagonals…
- [Can you notch a cushion to fit around a window casing?](https://cushionguide.com/answers/cushion-with-notch-cut-out-around-casing/): Yes, a window seat cushion can be notched to clear a window casing so it sits fully against the wall.
- [Which side of a cushion is the length and which is the width?](https://cushionguide.com/answers/cushion-length-vs-width-which-side-is-which/): On a cushion, length is the long side, measured left to right across the front, and width is the short side, measured from the front edge to the back edge, the same as seat depth.
- [How to measure a window seat cushion when the walls aren't square](https://cushionguide.com/guides/how-to-measure-window-seat-cushion/)
- [One long cushion or two? Splitting a long bench or window seat](https://cushionguide.com/guides/long-bench-cushion-one-piece-or-two/)

*± 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/how-to-measure-window-seat-cushion/