Knitting Decrease Calculator
How to Calculate Knitting Decreases Evenly
Whether you are shaping the crown of a hat, tapering a sleeve, or adjusting the waist of a sweater, calculating evenly spaced decreases is a fundamental skill for any knitter. While the math isn't overly complex, it can be tedious to perform manually in the middle of a project.
This Knitting Decrease Calculator determines exactly how to space your decreases across a row or round so that the fabric shapes smoothly without puckering or bias.
Why Even Spacing Matters
If you bunch all your decreases together (for example, at the beginning or end of a row), your fabric will slant aggressively in one direction. By distributing the decrease stitches (usually K2tog or SSK) evenly across the total stitch count, you ensure that the reduction in circumference or width happens symmetrically.
Understanding the Logic
The logic behind the decrease calculation involves dividing your current stitch count by the number of stitches you need to remove. This gives you a "group size."
Formula:
Total Stitches รท Decreases Needed = Stitch Interval
Total Stitches รท Decreases Needed = Stitch Interval
Often, the numbers don't divide perfectly. In these cases, the calculator splits the row into two slightly different group sizes to handle the remainder stitches seamlessly.
Common Abbreviations Used
- K: Knit
- K2tog: Knit two stitches together (a right-leaning decrease).
- SSK: Slip, Slip, Knit (a left-leaning decrease).
- Sts: Stitches.
Tips for Best Results
- Hat Crowns: When decreasing for a hat, you usually decrease a set number of stitches (often 8 or 10) every other round. Use the "Target Stitches" field to calculate one round at a time.
- Sleeves: Sleeve decreases are usually done at the edges (e.g., K1, K2tog… SSK, K1). This calculator is designed for distributed decreases across the whole row, not edge shaping.
- Check your count: Always count your stitches after a decrease row to ensure you hit your target number before proceeding to the next section of your pattern.
Calculation Result
" + "Decreases Needed: " + decreaseCount + " stitches" + "Warning: You are trying to decrease more than 50% of your stitches in a single row. Standard K2tog/SSK decreases cannot achieve this (as they turn 2 stitches into 1). You would need double decreases (K3tog) or binding off."; return; } // Calculation Logic // We need to divide 'current' stitches into 'decreaseCount' groups. // Each group will end with a decrease (consuming 2 stitches). var baseGroupSize = Math.floor(current / decreaseCount); var remainder = current % decreaseCount; // Logic explanation: // We have 'decreaseCount' total groups. // 'remainder' groups will be size (baseGroupSize + 1). // (decreaseCount – remainder) groups will be size (baseGroupSize). var largerGroups = remainder; var smallerGroups = decreaseCount – remainder; var largerGroupStitches = baseGroupSize + 1; var smallerGroupStitches = baseGroupSize; // The number of plain knit stitches before the K2tog is (GroupSize – 2). // If GroupSize is 2, we knit 0, then K2tog. var knitInLarger = largerGroupStitches – 2; var knitInSmaller = smallerGroupStitches – 2; var outputHTML = "Calculation Result
"; outputHTML += "Total Decreases: " + decreaseCount + " stitches
";
outputHTML += "Target: " + target + " stitches
";
outputHTML += "Pattern Instruction:";
var steps = [];
if (largerGroups > 0) {
var instruction = "";
if (knitInLarger > 0) {
instruction = "K" + knitInLarger + ", K2tog";
} else {
instruction = "K2tog";
}
if (largerGroups === 1) {
steps.push(instruction + " (once)");
} else {
steps.push("*" + instruction + "* " + largerGroups + " times");
}
}
if (smallerGroups > 0) {
var instruction = "";
if (knitInSmaller > 0) {
instruction = "K" + knitInSmaller + ", K2tog";
} else {
instruction = "K2tog";
}
if (smallerGroups === 1) {
steps.push(instruction + " (once)");
} else {
steps.push("*" + instruction + "* " + smallerGroups + " times");
}
}
outputHTML += steps.join(", then ") + ".
";
outputHTML += "Note: K2tog can be substituted with SSK depending on desired slant.";
resultDiv.style.display = "block";
resultDiv.innerHTML = outputHTML;
}