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Calcimator

Hat Sizing Calculator

Calculate cast-on stitches and crown decrease rounds for a knit hat based on head circumference, desired height, and gauge.

Inputs

in
in

Results

Cast-On Stitches

96 sts

Decrease Rounds

6

Body Rows (before decreases)44
Total Rows56
Adjusted Circumference19.8 in
Crown Diameter6.3 in
How to Use This Calculator
  1. Measure head circumference in inches with a flexible tape at the widest point above the ears.
  2. Enter your stitch gauge in stitches per inch from a blocked gauge swatch.
  3. Set the negative ease percentage (typically 10-15% for a fitted hat).
  4. Review the cast-on stitch count and expected hat height in rows.
  5. Use the recommended decrease round schedule to shape the crown.

How the result changes with Head Circumference

Head CircumferenceCast-On StitchesDecrease Rounds
1572 sts5
1988 sts6
23104 sts7
27120 sts8

What each input means

Head Circumference
Measure around the head just above the ears in inches. 10% negative ease is applied.
Hat Height
Total height of the hat from brim to crown in inches.
Stitch Gauge (per inch)
Stitches per inch from your gauge swatch.
Row Gauge (per inch)
Rows per inch from your gauge swatch.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Head Circumference = 22, Hat Height = 9, Stitch Gauge (per inch) = 5, Row Gauge (per inch) = 7 = 4 input(s) provided
  2. Calculate Cast-On Stitches
    96 = 96
  3. Calculate Decrease Rounds
    Decrease Rounds
    6 = 6
  4. Calculate Body Rows
    Body Rows
    44 = 44
  5. Calculate Total Rows
    Total Rows
    56 = 56

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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