.ft-in-calc-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 25px;
border: 1px solid #ddd;
border-radius: 8px;
background-color: #f9f9f9;
color: #333;
box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}
.ft-in-calc-container h2 {
text-align: center;
color: #2c3e50;
margin-bottom: 20px;
}
.calc-row {
display: flex;
gap: 10px;
margin-bottom: 15px;
align-items: center;
}
.input-group {
flex: 1;
}
.input-group label {
display: block;
font-size: 14px;
font-weight: bold;
margin-bottom: 5px;
}
.input-group input, .input-group select {
width: 100%;
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
box-sizing: border-box;
}
.calc-btn {
width: 100%;
padding: 12px;
background-color: #0073aa;
color: white;
border: none;
border-radius: 4px;
font-size: 16px;
cursor: pointer;
transition: background-color 0.3s;
}
.calc-btn:hover {
background-color: #005177;
}
.result-area {
margin-top: 20px;
padding: 15px;
background-color: #e7f3ff;
border-left: 5px solid #0073aa;
border-radius: 4px;
display: none;
}
.result-item {
margin: 10px 0;
font-size: 18px;
}
.result-item span {
font-weight: bold;
color: #0073aa;
}
.calc-article {
margin-top: 30px;
line-height: 1.6;
color: #444;
}
.calc-article h3 {
color: #2c3e50;
border-bottom: 2px solid #0073aa;
padding-bottom: 5px;
}
.calc-article ul {
padding-left: 20px;
}
.operation-select {
text-align: center;
margin: 10px 0;
}
.operation-select select {
width: 60px;
font-weight: bold;
font-size: 20px;
text-align: center;
}
Feet and Inches Calculator
+
−
Calculate Total
Result:
Total Inches:
Decimal Feet:
Metric (cm):
How to Add and Subtract Feet and Inches
Calculating measurements in the imperial system can be tricky because it doesn't use a base-10 system. Unlike meters or centimeters, there are 12 inches in a foot . This makes simple addition and subtraction difficult when you need to "carry over" or "borrow" values.
This calculator simplifies the process for construction, woodworking, and DIY projects. Whether you are measuring a room for flooring or cutting timber, getting the math right is crucial to avoid wasting materials.
Manual Calculation Method
If you don't have a calculator handy, here is the standard manual process:
Step 1: Convert both measurements entirely into inches. (Feet × 12 + Inches).Step 2: Add or subtract the total inches.Step 3: Divide the total inches by 12 to find the number of feet.Step 4: The remainder from that division is the remaining inches.
Practical Example
Imagine you have a board that is 5 feet 8 inches long and you need to add another board that is 2 feet 10 inches long.
Board 1: (5 * 12) + 8 = 68 inches
Board 2: (2 * 12) + 10 = 34 inches
Total: 68 + 34 = 102 inches
Conversion: 102 / 12 = 8 feet with 6 inches remaining.
Result: 8′ 6″
Units Reference Table
Unit
Equivalent
1 Foot
12 Inches
1 Yard
3 Feet (36 Inches)
1 Inch
2.54 Centimeters
function calculateFeetInches() {
var f1 = parseFloat(document.getElementById('feet1').value) || 0;
var i1 = parseFloat(document.getElementById('inches1').value) || 0;
var f2 = parseFloat(document.getElementById('feet2').value) || 0;
var i2 = parseFloat(document.getElementById('inches2').value) || 0;
var op = document.getElementById('operation').value;
// Convert everything to total inches
var totalInches1 = (f1 * 12) + i1;
var totalInches2 = (f2 * 12) + i2;
var finalInches = 0;
if (op === 'add') {
finalInches = totalInches1 + totalInches2;
} else {
finalInches = totalInches1 – totalInches2;
}
// Handle negative results for subtraction
var isNegative = finalInches < 0;
var absoluteInches = Math.abs(finalInches);
var resFeet = Math.floor(absoluteInches / 12);
var resInches = (absoluteInches % 12).toFixed(2);
// Clean up .00 from inches
if (resInches.endsWith('.00')) {
resInches = Math.floor(resInches);
}
var formatted = (isNegative ? "-" : "") + resFeet + "' " + resInches + '"';
var decimalFeet = (finalInches / 12).toFixed(3);
var metricCm = (finalInches * 2.54).toFixed(2);
// Update UI
document.getElementById('formattedResult').innerText = formatted;
document.getElementById('totalInchesResult').innerText = finalInches.toFixed(2) + ' in';
document.getElementById('decimalFeetResult').innerText = decimalFeet + ' ft';
document.getElementById('metricResult').innerText = metricCm + ' cm';
document.getElementById('result-box').style.display = 'block';
}