What are standard bolster sizes?

Common bolster sizes are 15cm diameter x 40cm long (small), 20cm x 50cm (medium), and 25cm x 65cm (large). Neck roll bolsters are typically 15cm x 35cm. Measure your bolster pad or desired finished size.

How do I cut the end circles?

Cut circles with the diameter plus seam allowance. Use a compass or trace around a plate. Notch the circle into quarters. Clip the seam allowance of the circle to help ease it into the tube when sewing.

Where should I put the zip?

Place a concealed zip along the length of the main body piece. The zip should be about 5cm shorter than the bolster length. Alternatively, use an envelope-style opening at one end.

How do I get smooth end circles?

Pin the circle to the tube at quarter marks first, then ease the rest. Clip the seam allowance of the circle at 1cm intervals. Sew slowly around the curve. A piped edge hides any slight irregularities.

SewCalcs

Bolster Calculator — Bolster Cushion Fabric

Calculate fabric for cylindrical bolster cushion covers.

Bolster Diameter

Finished diameter of the bolster pad (e.g. 20 cm)

Bolster Length

Finished length end-to-end (e.g. 50 cm)

Seam Allowance

Per edge — 1.5 cm (⅝ in) is the UK/Big-4 standard

Fabric Width

Usable width of your fabric bolt — UK cottons ~110 cm, furnishing ~137-150 cm

Fabric Price (optional)

Price per metre to estimate cost (optional)

How We Calculate This

A bolster cover consists of a rectangular main body (circumference × length) and two circular end pieces. The main body wraps around the cylinder.

The formula

Circumference = π × Diameter

Main body = (Circumference + Seams) × (Length + Seams)

End circles = Diameter + (Seam × 2)

Fabric needed depends on your bolt width: if the body and both end circles fit side-by-side across the width they cut from a single band; if not, the circles drop to a second band below. When the wrap itself is wider than the fabric, the body must be railroaded down the length or pieced with a seam. The total is rounded up to the next 0.1 m.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before cutting or purchasing fabric.