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

Bolster Length

Seam Allowance

Fabric Width

Fabric Price (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)

Frequently Asked Questions

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Last updated: February 2026

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