body {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f8f9fa;
color: #333;
line-height: 1.6;
margin: 0;
padding: 20px;
}
.wallpaper-calc-container {
max-width: 700px;
margin: 30px auto;
background-color: #ffffff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}
h1, h2 {
color: #004a99;
text-align: center;
margin-bottom: 20px;
}
.input-group {
margin-bottom: 15px;
display: flex;
flex-direction: column;
}
.input-group label {
display: block;
margin-bottom: 8px;
font-weight: bold;
color: #004a99;
}
.input-group input[type="number"] {
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 1em;
box-sizing: border-box; /* Ensures padding doesn't affect width */
}
.input-group input[type="number"]:focus {
border-color: #004a99;
outline: none;
box-shadow: 0 0 0 2px rgba(0, 74, 153, 0.2);
}
button {
background-color: #28a745;
color: white;
padding: 12px 20px;
border: none;
border-radius: 4px;
font-size: 1.1em;
cursor: pointer;
transition: background-color 0.3s ease;
width: 100%;
margin-top: 20px;
}
button:hover {
background-color: #218838;
}
#result {
margin-top: 30px;
padding: 20px;
background-color: #e9ecef;
border: 1px solid #dee2e6;
border-radius: 4px;
text-align: center;
}
#result h3 {
margin-top: 0;
color: #004a99;
}
.result-value {
font-size: 1.8em;
font-weight: bold;
color: #004a99;
}
.notes {
font-size: 0.9em;
color: #6c757d;
margin-top: 10px;
}
.article-section {
margin-top: 40px;
padding-top: 30px;
border-top: 1px solid #eee;
}
.article-section h2 {
text-align: left;
color: #004a99;
}
.article-section p, .article-section ul {
margin-bottom: 15px;
}
.article-section li {
margin-bottom: 8px;
}
/* Responsive adjustments */
@media (max-width: 768px) {
.wallpaper-calc-container {
padding: 20px;
}
button {
font-size: 1em;
}
.result-value {
font-size: 1.5em;
}
}
Understanding Wallpaper Calculations
Wallpapering a room can seem daunting, but with the right calculations, you can ensure you buy enough material without overspending. This calculator simplifies the process by estimating the number of wallpaper rolls required based on your room dimensions and wallpaper specifications.
How the Calculation Works
The core of the calculation involves determining the total surface area of the walls to be wallpapered and then dividing that by the area covered by a single roll of wallpaper. We also account for common obstacles like doors and windows, and the crucial factor of pattern repeat.
1. Calculate Wall Surface Area:
The total perimeter of the room is calculated by adding the lengths of all four walls: `Perimeter = 2 * (Room Width + Room Length)`. The total wall area is then the perimeter multiplied by the room's height: `Total Wall Area = Perimeter * Room Height`.
2. Subtract Obstacle Areas:
Areas like doors and windows do not need wallpaper. We calculate their individual areas: `Door Area = Door Width * Door Height` and `Window Area = Window Width * Window Height`. These are then subtracted from the Total Wall Area to get the net area to be covered: `Net Wall Area = Total Wall Area – Door Area – Window Area`.
3. Account for Wallpaper Roll Coverage:
Each roll of wallpaper has a specific width and length. The area covered by one roll is `Roll Area = Wallpaper Roll Width * Wallpaper Roll Length`.
4. Incorporate Pattern Repeat:
Wallpaper often has a design that needs to align between strips (pattern repeat). This means you lose some usable length from each strip to match the pattern. For each strip, you effectively need to account for the pattern repeat. The number of full strips you can get from a roll is calculated as `Number of Strips per Roll = Floor(Wallpaper Roll Length / (Room Height + Pattern Repeat))`. The total area covered by one roll, considering pattern repeat, is then `Effective Roll Area = Number of Strips per Roll * Wallpaper Roll Width * Room Height`.
Note: If the pattern repeat is 0, this simplifies to `Effective Roll Area = Roll Area`. The calculator uses a more direct method of calculating the number of drops needed and then how many drops come from a roll.
5. Calculate Total Rolls Needed:
The total number of wallpaper strips required is determined by dividing the room's perimeter by the wallpaper roll's width: `Total Strips Needed = Ceiling(Perimeter / Wallpaper Roll Width)`. However, this doesn't account for pattern repeat and wastage. A more robust method is to calculate how many vertical strips (drops) of wallpaper, each equal to the room's height plus any required pattern repeat, can be obtained from a single roll.
The calculator determines:
- The number of vertical drops needed: `Drops Needed = Ceiling(Net Wall Area / Wallpaper Roll Width)`. (This is a simplification, the actual calculation is more complex).
- The number of full vertical strips (drops) you can cut from one roll: `Drops per Roll = Floor(Wallpaper Roll Length / (Room Height + Pattern Repeat))`.
- The total number of rolls is then `Total Rolls = Ceiling(Drops Needed / Drops per Roll)`.
Wastage & Practicality: This calculation provides an estimate. It's always recommended to add 10-15% extra for cuts, potential mistakes, future repairs, or if you have a large pattern repeat that requires more trimming. This calculator aims for a precise minimum, so purchasing an extra roll is a common practice.
When to Use This Calculator:
- Estimating wallpaper quantities for living rooms, bedrooms, hallways, and accent walls.
- Comparing different wallpaper roll sizes and pattern repeats.
- Budgeting for a wallpapering project.
By accurately calculating your wallpaper needs, you can ensure a smooth and successful decorating project.
function calculateWallpaper() {
var roomWidth = parseFloat(document.getElementById('roomWidth').value);
var roomLength = parseFloat(document.getElementById('roomLength').value);
var roomHeight = parseFloat(document.getElementById('roomHeight').value);
var doorWidth = parseFloat(document.getElementById('doorWidth').value);
var doorHeight = parseFloat(document.getElementById('doorHeight').value);
var windowWidth = parseFloat(document.getElementById('windowWidth').value);
var windowHeight = parseFloat(document.getElementById('windowHeight').value);
var wallpaperRollWidth = parseFloat(document.getElementById('wallpaperRollWidth').value);
var wallpaperRollLength = parseFloat(document.getElementById('wallpaperRollLength').value);
var patternRepeat = parseFloat(document.getElementById('patternRepeat').value);
var errorMessage = "";
if (isNaN(roomWidth) || roomWidth <= 0) errorMessage += "Please enter a valid Room Width.\n";
if (isNaN(roomLength) || roomLength <= 0) errorMessage += "Please enter a valid Room Length.\n";
if (isNaN(roomHeight) || roomHeight <= 0) errorMessage += "Please enter a valid Room Height.\n";
if (isNaN(doorWidth) || doorWidth < 0) errorMessage += "Please enter a valid Door Width (or 0).\n";
if (isNaN(doorHeight) || doorHeight < 0) errorMessage += "Please enter a valid Door Height (or 0).\n";
if (isNaN(windowWidth) || windowWidth < 0) errorMessage += "Please enter a valid Window Width (or 0).\n";
if (isNaN(windowHeight) || windowHeight < 0) errorMessage += "Please enter a valid Window Height (or 0).\n";
if (isNaN(wallpaperRollWidth) || wallpaperRollWidth <= 0) errorMessage += "Please enter a valid Wallpaper Roll Width.\n";
if (isNaN(wallpaperRollLength) || wallpaperRollLength <= 0) errorMessage += "Please enter a valid Wallpaper Roll Length.\n";
if (isNaN(patternRepeat) || patternRepeat < 0) errorMessage += "Please enter a valid Pattern Repeat (or 0).\n";
if (errorMessage !== "") {
alert(errorMessage);
document.getElementById('rollsNeeded').innerHTML = "–";
return;
}
// Calculate perimeter
var perimeter = 2 * (roomWidth + roomLength);
// Calculate total wall area
var totalWallArea = perimeter * roomHeight;
// Calculate area of door and window
var doorArea = doorWidth * doorHeight;
var windowArea = windowWidth * windowHeight;
// Calculate net wall area to be covered
var netWallArea = totalWallArea – doorArea – windowArea;
// Ensure net area is not negative
if (netWallArea 0 && dropLengthWithRepeat > 0) {
// Fallback: Assume we can get at least one drop if roll length is sufficient for room height only
// Or signal an error if roll isn't long enough for even one height + repeat.
if (wallpaperRollLength = room height
} else if (dropsPerRoll === 0) { // Handle cases where roll length or height might be 0 or invalid leading to 0
dropsPerRoll = 1; // Default to 1 if calculation yields 0 unexpectedly but inputs are valid
}
// Calculate total number of strips (drops) needed for the perimeter
// Each strip is wallpaperRollWidth wide.
var totalStripsNeeded = Math.ceil(perimeter / wallpaperRollWidth);
// Calculate total rolls required
var totalRolls = Math.ceil(totalStripsNeeded / dropsPerRoll);
// Ensure at least one roll is suggested if any area needs covering
if (netWallArea > 0 && totalRolls < 1) {
totalRolls = 1;
} else if (netWallArea === 0) {
totalRolls = 0; // No wallpaper needed if net area is zero or less
}
document.getElementById('rollsNeeded').innerHTML = totalRolls;
}