fiber_pattern

Tools for pattern sizing, stitch repeats, and gauge-based calculations for knitting and crochet.

fiber_pattern builds on the primitives provided by:

• fiber_units — typed units for stitches, rows, and measurements
• fiber_gauge — gauge swatch math

Together they enable reliable pattern sizing and repeat calculations.

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Installation

Add this line to your application's Gemfile:

gem "fiber_pattern"

Then run:

bundle install

Or install directly:

gem install fiber_pattern

Dependencies

fiber_pattern is designed to work with:

fiber_units
fiber_gauge

These libraries provide the domain primitives used throughout the API.

Basic Usage

Patterns often require calculating stitch counts from gauge and measurements.

Example gauge:

18 stitches over 4 inches
24 rows over 4 inches

Create a gauge object:

gauge = FiberGauge::Gauge.new(
  stitches: 18.stitches,
  rows: 24.rows,
  width: 4.inches
)

Calculate Cast-On Stitches

You can determine how many stitches are needed for a target width.

sizing = FiberPattern::Sizing.new(gauge: gauge)

sizing.cast_on_for(20.inches)
# => 90 stitches

Because:

18 stitches / 4 inches = 4.5 stitches per inch
20 inches × 4.5 = 90 stitches

Pattern Stitch Repeats

Use FiberPattern::Repeat when a pattern requires stitch counts to align to a repeat.

Many patterns require stitch counts to be a multiple of a repeat.

Example: multiple of 8 stitches

sizing = FiberPattern::Sizing.new(
  gauge: gauge,
  repeat: FiberPattern::Repeat.new(multiple: 8.stitches)
)

sizing.cast_on_for(38.inches)
# => 176 stitches

Calculation:

38 inches × 4.5 spi = 171 stitches
rounded to nearest multiple of 8 → 176

Repeats With Offsets

Some stitch patterns require multiples plus an offset.

Example:

multiple of 8 + 2

sizing = FiberPattern::Sizing.new(
  gauge: gauge,
  repeat: FiberPattern::Repeat.new(
    multiple: 8.stitches,
    offset: 2.stitches
  )
)

sizing.cast_on_for(38.inches)
# => 178 stitches

Calculation:

171 stitches
→ adjusted to (multiple of 8 + 2)
→ 178 stitches

Gauge Scaling

You can also scale stitch and row counts from a pattern's gauge to a knitter's gauge.

pattern_gauge = FiberGauge::Gauge.new(
  stitches: 20.stitches,
  rows: 28.rows,
  width: 4.inches
)

knitter_gauge = FiberGauge::Gauge.new(
  stitches: 18.stitches,
  rows: 24.rows,
  width: 4.inches
)

FiberPattern::Scaling.scale_stitches(
  100.stitches,
  pattern_gauge,
  knitter_gauge
)
# => 90 stitches

FiberPattern::Scaling.scale_rows(
  56.rows,
  pattern_gauge,
  knitter_gauge
)
# => 48 rows

Example: Sweater Sizing

gauge = FiberGauge::Gauge.new(
  stitches: 20.stitches,
  rows: 28.rows,
  width: 4.inches
)

sizing = FiberPattern::Sizing.new(
  gauge: gauge,
  repeat: FiberPattern::Repeat.new(multiple: 8.stitches)
)

chest = 40.inches

cast_on = sizing.cast_on_for(chest)
# => 200 stitches

Design Goals

fiber_pattern is designed to:

• make pattern math predictable
• integrate with typed fiber measurement units
• support repeat-based stitch patterns
• help scale instructions between gauges
• stay small and composable

It forms part of a broader fiber tooling ecosystem:

• fiber_units
• yarn_skein
• fiber_gauge
• fiber_pattern

Contributing

Bug reports and pull requests are welcome.

License

MIT License