How much overhang do I need for batting?

For domestic machine quilting, 5cm (2 inches) overhang on each side is sufficient. For longarm quilting, allow 10 to 15cm (4 to 6 inches) on each side as the fabric needs to be loaded onto the frame and kept taut during quilting.

Why does the backing need more overhang than the batting?

The backing needs extra overhang (typically 10cm per side for domestic, 15 to 20cm for longarm) because it is stretched and pinned or loaded onto a frame. It must be larger than the batting to ensure full coverage and allow for any shifting during quilting.

How do I piece a quilt backing?

If your quilt is wider than a single fabric width, sew two or more panels together with a 1cm seam allowance. Press seams open to reduce bulk. You can place the seam centrally or offset it for a less noticeable join. Avoid placing a seam directly down the centre of the quilt.

SewCalcs

Quilt Sandwich Calculator

Calculate batting and backing sizes needed for a quilt top, including overhang allowances.

Quilt Top Width

Finished quilt top width

Quilt Top Length

Finished quilt top length

Quilting MethodAffects overhang allowances

Backing Fabric Width

Bolt width: UK quilting cotton 112cm (44in); ~5cm is lost to selvedges leaving ~107cm usable

How We Calculate This

Batting Size

Batting = Quilt Top + (Overhang x 2) on both width and length

Backing Size

Backing = Quilt Top + (Backing Overhang x 2)

Usable fabric width is the bolt width minus ~5cm for selvedges, so 112cm cotton gives about 107cm of usable width.

If the backing is wider than a single usable width, panels are pieced together. The calculator works out the fabric needed both ways — panels running the length (vertical seams) and panels running the width (horizontal seams) — and quotes whichever uses less fabric.

Frequently Asked Questions

Related Calculators

Quilt Size Calculator

Calculate quilt dimensions for standard bed sizes with drop allowances.

Quilt Binding Calculator

Calculate binding strip fabric and length for finishing quilts.

Quilt Backing Calculator

Work out backing fabric needed with seaming for wide quilts.

Quilt Block Calculator

Calculate number of blocks and fabric for a quilt layout.

Strip Piecing Calculator

Calculate strip quantities for strip-pieced quilt blocks and designs.

Last updated: March 2026

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