What pieces need interfacing?

Common interfaced pieces include collars, collar stands, cuffs, front button bands/plackets, facings (neckline, armhole), waistbands, pocket flaps, and any area that needs extra body or structure.

What type of interfacing should I use?

Fusible (iron-on) interfacing is quickest to apply and suitable for most projects. Sew-in interfacing is better for heat-sensitive fabrics, sheers, and very textured fabrics where fusible may not bond properly. Choose a weight lighter than or equal to your fabric weight.

What width does interfacing come in?

Fusible interfacing is commonly 90cm wide. Some brands offer wider rolls at 112cm or 150cm. Woven interfacings tend to be 90cm, while non-woven fusible may be wider. Check before purchasing.

Should I pre-shrink interfacing?

Yes, fusible interfacing should be pre-shrunk by soaking in lukewarm water for 10 minutes and air drying before use. This prevents puckering when the finished garment is washed. Non-fusible sew-in interfacing should also be pre-shrunk.

SewCalcs

Interfacing Calculator — Fusible & Sew-In Interfacing

Calculate how much interfacing you need for garment pieces such as collars, cuffs, facings and waistbands.

Number of Pieces

Total interfacing pieces to cut

Interfacing Width

Roll width of your interfacing

Piece Length

Piece Width

Price Per Metre (optional)

How We Calculate This

This calculator works out how many interfacing pieces fit across the roll width, then calculates the total length needed.

The formula

Pieces across = floor(Interfacing width ÷ Piece width)

Rows = ceil(Number of pieces ÷ Pieces across)

Length needed = Rows × Piece length

Frequently Asked Questions

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Last updated: February 2026

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