How to Measure Cushions for Fabric: Width, Length & Thickness

Updated: May 26, 2026

What You Need

A rigid tape measure or metal ruler (fabric tapes stretch)
The cushion insert, foam pad, or existing cushion you’re covering
Notepad or phone to record dimensions

How to Measure a Box Cushion Insert

You need three measurements: width, length, and thickness.

Width

Measure across the shorter dimension of the cushion face — from edge to edge. If the cushion tapers or has irregular edges, measure at the widest point.

Length

Measure across the longer dimension — from front edge to back edge of the cushion face.

Thickness

Measure the depth of the cushion at its thickest point. For foam inserts, measure the foam block itself. For down/fiber fill, measure the existing cushion while it’s slightly compressed (overstuffed cushions will settle).

Measuring tip: For recovering existing cushions, measure the foam insert inside — not the old cover. Old covers often stretch; measuring the cover gives you incorrect numbers.

Measuring a Square Cushion Insert

Even if the insert looks square, measure both directions — many “square” cushions are slightly rectangular. Use both numbers separately.

Measuring for a Knife-Edge Pillow

Only two measurements needed:

Width (shorter side)
Height / Length (longer side, or the same if square)

No thickness measurement — knife-edge pillows have no boxing strip. The pillow puffs to its natural thickness when stuffed.

Tip for existing pillow covers: Measure the finished cover size, not just the insert. The finished cover is typically ½”–1” smaller than the insert to ensure a snug fit. Enter the cover size (slightly smaller than insert) as your finished width and length.

Measuring a Round Cushion

Only one measurement needed:

Diameter — measure across the widest point of the circle, through the center

If adding a boxing strip, also measure:

Thickness — same as box cushion

Tip: If tracing an existing cushion for a new cover, lay the cushion flat on paper, trace around it, and measure the diameter of the traced circle. This accounts for any slight irregularity in a hand-cut or worn cushion.

Measuring a Bench Cushion

Bench cushions are long rectangular box cushions. Measure:

Width — front to back of the bench seat
Length — left to right across the full bench width
Thickness — depth of the cushion/foam

For benches with a back panel or arm notches (T-shaped or L-shaped), note the notch dimensions separately. A standard box cushion calculator doesn’t cover notched shapes — those require custom pattern-making. For typical bench yardage by bench type, see Bench Cushion Fabric Guide.

Measuring a Chaise Lounge Cushion

Chaise cushions are typically very long (60”–84”) and may taper in width. Measure:

Width at the widest point (usually the top/head end)
Length along the longest dimension
Thickness at the thickest point (usually the seat area)

If the chaise cushion has an angled end or a two-part articulated design, measure each section separately.

Accounting for Foam Compression

Foam inserts compress under weight. A 4”-thick foam block feels “full” when the cover is made exactly to the foam’s uncompressed dimensions. If you want a “firm” look, make the cover ½” smaller than the foam in each direction — the foam compresses slightly to fill the snug cover.

If you want a “relaxed” look, make the cover exactly the foam size. The cover will look slightly loose when the cushion is unweighted.

Standard practice: Make the cover exactly the foam insert dimensions (enter the uncompressed foam size as finished dimensions in the calculator).

Double-Checking Before Cutting

After measuring, verify:

Does width × length × thickness describe the cushion insert accurately?
For bench cushions: Is the “length” going across the full bench (including any overhang) or just the seat area?
For outdoor cushions: Will the cover need to fit tightly or loosely? (Outdoor foam typically needs a tighter cover to prevent excess movement in wind.) See How to Calculate Fabric for Outdoor Cushions for outdoor-specific sizing and fabric notes.
For recovers: Did you measure the insert (foam) or the old cover? Use the insert.

Enter your measurements directly into the Cushion Fabric Calculator to get cut dimensions and total yardage.