Crochet Sphere Calculator

Amigurumi Crochet Sphere Calculator

Calculate perfect stitch counts and rounds for any yarn weight.

10cm x 10cm 4″ x 4″ 1cm or 1″

How to Use the Crochet Sphere Calculator

Creating perfectly round spheres for amigurumi can be tricky when switching between different yarn weights. Whether you are using bulky velvet yarn or fine lace cotton, this calculator translates your physical size goals into a workable crochet pattern.

Understanding the Inputs

  • Target Diameter: The actual width you want the finished sphere to be.
  • Stitch & Row Gauge: This is the most critical part. Crochet a small square (e.g., 10cm x 10cm) with your chosen hook and yarn. Count how many stitches fit across and how many rows fit vertically.
  • Magic Ring Start: Most spheres start with 6 stitches (standard for SC). If you find your sphere is too "pointy" at the poles, some designers use 8 stitches (standard for HDC).

The Math Behind the Ball

The calculator uses the geometry of a circle to determine the "equator." The circumference of your sphere is Diameter × π. By applying your stitch gauge to that circumference, we find the maximum number of stitches required at the widest point. To maintain a round shape, the number of increase rounds must be balanced by an equal number of decrease rounds, with "even rounds" in the middle to account for the vertical height of the stitches.

Realistic Example

If you want a 10cm sphere and your gauge is 20 stitches and 20 rows per 10cm:

  • Max Stitches: Approximately 62-66 stitches.
  • Increase Phase: You will increase by 6 stitches every round for about 10-11 rounds.
  • Middle Phase: You will work several rounds even (no increases).
  • Decrease Phase: You will mirror the increases using invisible decreases.
function calculateSphere() { var diameter = parseFloat(document.getElementById('diameter').value); var gaugeSize = parseFloat(document.getElementById('gaugeSize').value); var stitchGauge = parseFloat(document.getElementById('stitchGauge').value); var rowGauge = parseFloat(document.getElementById('rowGauge').value); var incPerRound = parseInt(document.getElementById('incPerRound').value); if (isNaN(diameter) || isNaN(stitchGauge) || isNaN(rowGauge) || isNaN(incPerRound)) { alert("Please fill in all fields with valid numbers."); return; } // 1. Calculate target circumference var circumference = diameter * Math.PI; // 2. Calculate stitches at max diameter // (Circumference / gaugeSize) * stitchGauge var rawMaxStitches = (circumference / gaugeSize) * stitchGauge; // 3. Round max stitches to the nearest multiple of the increase rate var numIncRounds = Math.round(rawMaxStitches / incPerRound); var maxStitches = numIncRounds * incPerRound; // 4. Calculate total rows required for the full diameter height var totalRows = Math.round((diameter / gaugeSize) * rowGauge); // 5. The "even" rounds are the total rows minus the rows used for inc/dec // Increase phase takes numIncRounds. Decrease phase takes numIncRounds. var evenRounds = totalRows – (2 * numIncRounds); // Safety check for small spheres if (evenRounds < 0) { evenRounds = 1; } // 6. Calculate yarn estimate (total stitches) var totalStitchesInProject = 0; // Increases for (var i = 1; i = 1; j–) { totalStitchesInProject += (j * incPerRound); } // Add the final closure (approx 1 round) totalStitchesInProject += incPerRound; var resultDiv = document.getElementById('sphereResult'); resultDiv.style.display = 'block'; var output = '

Your Sphere Pattern Specifications

'; output += '
'; output += '
Maximum Stitches:' + maxStitches + ' sts
'; output += '
Increase Rounds:' + numIncRounds + ' rounds
'; output += '
Even Rounds:' + evenRounds + ' rounds
'; output += '
Total Rows:' + (numIncRounds * 2 + evenRounds) + ' rows
'; output += '
'; output += '
'; output += 'Total Project Stitches: ~' + totalStitchesInProject + ' stitches'; output += 'Estimate for yarn yardage calculation.'; output += '
'; output += '
'; output += 'Pattern Logic: Increase by ' + incPerRound + ' each round until round ' + numIncRounds + ' (' + maxStitches + ' sts). Work even for ' + evenRounds + ' rounds. Decrease by ' + incPerRound + ' each round until closed.'; output += '
'; resultDiv.innerHTML = output; }

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