.quilt-calculator-wrapper {
max-width: 800px;
margin: 0 auto;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
background: #fdfdfd;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 20px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.quilt-calc-header {
text-align: center;
margin-bottom: 25px;
background-color: #6b4c9a;
color: white;
padding: 15px;
border-radius: 6px;
}
.quilt-calc-header h2 {
margin: 0;
font-size: 24px;
}
.quilt-form-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 20px;
}
.quilt-input-group {
display: flex;
flex-direction: column;
}
.quilt-input-group label {
font-weight: 600;
margin-bottom: 8px;
color: #333;
font-size: 14px;
}
.quilt-input-group input, .quilt-input-group select {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
}
.quilt-input-group .hint {
font-size: 12px;
color: #666;
margin-top: 4px;
}
.quilt-btn {
width: 100%;
padding: 12px;
background-color: #6b4c9a;
color: white;
border: none;
border-radius: 4px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.2s;
margin-top: 10px;
}
.quilt-btn:hover {
background-color: #563d7c;
}
.quilt-results {
margin-top: 25px;
padding: 20px;
background-color: #f4f0f9;
border-radius: 6px;
border-left: 5px solid #6b4c9a;
display: none;
}
.quilt-results h3 {
margin-top: 0;
color: #6b4c9a;
}
.result-row {
display: flex;
justify-content: space-between;
padding: 10px 0;
border-bottom: 1px solid #ddd;
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
font-weight: 600;
color: #444;
}
.result-value {
font-weight: bold;
color: #222;
}
.highlight-cut {
font-size: 24px;
color: #d32f2f;
font-weight: 800;
}
/* Article Styles */
.quilt-content {
max-width: 800px;
margin: 40px auto;
line-height: 1.6;
color: #333;
font-family: Georgia, serif;
}
.quilt-content h2 {
font-family: -apple-system, sans-serif;
color: #2c3e50;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
margin-top: 30px;
}
.quilt-content h3 {
font-family: -apple-system, sans-serif;
color: #6b4c9a;
margin-top: 25px;
}
.quilt-content ul {
background: #f9f9f9;
padding: 20px 40px;
border-radius: 6px;
}
.quilt-content li {
margin-bottom: 10px;
}
@media (max-width: 600px) {
.quilt-form-grid {
grid-template-columns: 1fr;
}
}
function calculateQuiltSquares() {
// Get Inputs
var finishedSize = parseFloat(document.getElementById('q_finished_size').value);
var seamAllowance = parseFloat(document.getElementById('q_seam').value);
var quiltWidth = parseFloat(document.getElementById('q_width').value);
var quiltLength = parseFloat(document.getElementById('q_length').value);
// Error Handling
if (isNaN(finishedSize) || finishedSize <= 0) {
alert("Please enter a valid finished block size greater than 0.");
return;
}
if (isNaN(seamAllowance) || seamAllowance 0 && !isNaN(quiltLength) && quiltLength > 0) {
hasDimensions = true;
// We divide the total dimension by the FINISHED size of the block, not the cut size.
// Math.ceil ensures we have enough blocks to cover the area.
squaresAcross = Math.ceil(quiltWidth / finishedSize);
squaresDown = Math.ceil(quiltLength / finishedSize);
totalSquares = squaresAcross * squaresDown;
}
// 3. Update UI
document.getElementById('res_cut_size').innerHTML = cutSize + '" x ' + cutSize + '"';
document.getElementById('res_seam_total').innerHTML = (seamAllowance * 2) + '"';
if (hasDimensions) {
document.getElementById('grid_results').style.display = 'block';
document.getElementById('res_grid_layout').innerText = squaresAcross + ' across by ' + squaresDown + ' down';
document.getElementById('res_total_squares').innerText = totalSquares + ' squares';
// Calculate actual finished dimensions based on block count (to see if it exceeds target slightly)
var actualWidth = squaresAcross * finishedSize;
var actualLength = squaresDown * finishedSize;
document.getElementById('res_final_dim').innerText = actualWidth + '" x ' + actualLength + '"';
} else {
document.getElementById('grid_results').style.display = 'none';
}
// Show Results Container
document.getElementById('quilt_results_box').style.display = 'block';
}
Mastering Quilt Math: The Square Size Guide
Whether you are a beginner quilter creating your first patchwork blanket or an experienced fiber artist designing a complex mosaic, getting your math right before cutting fabric is the single most critical step in the process. The Quilt Square Size Calculator above eliminates the guesswork by determining exactly how large to cut your fabric pieces to achieve your desired "finished" block size.
Why Do "Cut" and "Finished" Sizes Differ?
In quilting, dimensions are always discussed in two terms:
- Finished Size: The size the block will be after it is sewn into the quilt top. This is the visual size you see in the final pattern.
- Cut Size (Unfinished Size): The actual size you must cut the fabric from the bolt or stash. This includes the extra fabric necessary to sew the pieces together.
The difference between these two numbers is determined by the seam allowance. In standard quilting, the universal seam allowance is 1/4 inch (0.25″).
The Magic Formula for Squares
Because a square has seams on all four sides (left, right, top, and bottom), you must account for the seam allowance on opposing sides to determine the cut width and height.
If your seam allowance is 1/4 inch, you lose 1/4 inch on the left and 1/4 inch on the right. Therefore, the formula is:
Cut Size = Finished Size + 0.5 inches
Examples:
- For a 4″ finished square, cut your fabric to 4.5″.
- For a 10″ finished square (often used with Layer Cakes), cut your fabric to 10.5″.
- For a 12″ finished block, cut your fabric to 12.5″.
Planning a Full Quilt
When planning a quilt of a specific size (e.g., a Twin size approx. 70″ x 90″), you need to calculate how many blocks will fit into that grid. To do this, always divide the target quilt dimension by the Finished Block Size, not the cut size.
For example, if you want a quilt width of 60 inches using 5-inch finished squares:
60 inches รท 5 inches = 12 blocks across.
The calculator above performs this division for you, rounding up to the nearest whole block to ensure you have enough squares to cover your target area.
Tips for Precision Cutting
Even with the correct math, cutting accuracy is paramount.
- Press your fabric: Always iron fabric before cutting to remove wrinkles that distort measurements.
- Use a rotary cutter: Scissors are rarely accurate enough for geometric quilting. Use a rotary cutter, self-healing mat, and an acrylic ruler.
- Measure twice: "Measure twice, cut once" is the golden rule to avoid wasting expensive fabric.
- Check your seam allowance: Sew a test block and measure it. If your 4.5″ cut square doesn't result in a 4.0″ finished square, your sewing machine's 1/4″ foot might need adjustment.