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Directional Fabric Calculator — One-Way Print & Nap Allowance
Calculate extra fabric needed when using directional prints, napped fabrics, or large pattern repeats.
How We Calculate This
Directional fabrics require all pattern pieces to be laid out in one direction, which wastes more fabric. These tiers are approximate rules of thumb — always use the “with nap” yardage printed on your pattern envelope when one is given. If it is not, the common convention is to add about 20% to the standard requirement for any napped or one-way fabric.
- Slight directional: +10%
- One-way print: +15%
- Nap/pile (velvet, corduroy): +20%
- Large pattern repeat / plaid: +25% (12″+ repeats can need up to 50%)
Narrower bolts also nest one-way pieces less efficiently, so this tool adds a small extra allowance on 137 cm and 112 cm widths compared with wide 150 cm cloth.
The formula
Total fabric = Base × (1 + Directional% + Width%) × (1 + Shrinkage%) + Selvedge
The core estimate is Base × (1 + Extra%); the shrinkage factor and flat selvedge allowance (both in Advanced Options) are then applied and the result is rounded up to the nearest 0.1 m.
Frequently Asked Questions
A directional fabric has a design, texture or shading that runs in one direction. One-way prints (flowers pointing up, animals facing one way), napped fabrics (velvet, corduroy, brushed cotton), and fabrics with a visible grain direction all require all pattern pieces to be laid in the same direction.
With non-directional fabric, you can flip pattern pieces upside down to fit them more efficiently. With directional fabric, all pieces must point the same way, so there is more wasted space between pieces. This typically adds 10–25% to your requirements.
Hold the fabric upright and look at the print — if it looks wrong upside down, it is directional. For nap, run your hand along the fabric in both directions — if the colour looks different, it has a nap.
Related Calculators
Nap Layout Calculator
Calculate extra fabric needed for one-way, nap and directional pattern layouts.
Pattern Matching Calculator
Calculate extra fabric needed for pattern matching across multiple garment pieces.
Bias Binding Calculator
Calculate fabric needed to make continuous bias binding strips.
Bias Tape Calculator
Calculate the fabric square size needed to make bias tape and see how much tape a given square will yield.
Fabric Shrinkage Calculator
Calculate how much extra fabric to buy to account for pre-wash shrinkage.
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Last updated: February 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.