Calculate the exact pixel width of your screen or any display based on its height and diagonal measurement.
Your Screen Width is: N/A
Understanding Screen Width Calculation
The screen width calculator helps determine the precise pixel width of a display. This is particularly useful for graphic designers, web developers, and content creators who need exact display specifications for layout planning, asset creation, and ensuring content displays correctly across various devices. The calculation primarily relies on the screen's height in pixels and its diagonal measurement in inches, combined with its aspect ratio.
The Math Behind the Calculation
The relationship between a screen's width (W), height (H), and diagonal (D) is governed by the Pythagorean theorem:
W² + H² = D_pixels²
Where W and H are in pixels, and D_pixels is the diagonal length measured in pixels.
The diagonal measurement in inches (D_inches) is related to the diagonal in pixels by the screen's effective Pixels Per Inch (PPI):
D_pixels = D_inches × PPI
Substituting this back into the Pythagorean theorem:
W² + H² = (D_inches × PPI)²
To calculate the screen width (W) when the height (H) and diagonal in inches (D_inches) are known, we also need the screen's Aspect Ratio. The aspect ratio is the proportional relationship between the screen's width and its height (AR = W / H).
This calculator uses the following logic:
Aspect Ratio Determination:
If you provide both the Display Width (pixels) and Display Height (pixels), the calculator derives the Aspect Ratio from these values (AR = Display Width / Display Height).
If you only provide Display Height (pixels) (or an invalid Display Width), the calculator defaults to a standard 16:9 aspect ratio, which is common for most modern monitors and TVs.
Width Calculation:
Once the Aspect Ratio (AR) is determined, the screen width (W) is calculated using the provided Display Height (H):
W = H × AR
The Screen Diagonal (inches) is a required input for context and physical screen dimension validation, though the primary calculation for pixel width relies on height and aspect ratio.
Use Cases
Web Development: Plan responsive layouts and ensure elements scale correctly.
Graphic Design: Create assets (images, videos) at the correct resolution for specific display sizes.
Content Creation: Optimize video or image dimensions for display on monitors and screens.
Display Specification Verification: Understand the pixel dimensions implied by a screen's physical size and common aspect ratios.
By understanding and utilizing these calculations, you can ensure your digital content is presented optimally across the vast array of display technologies available today.
function calculateScreenWidth() {
var w_input_str = document.getElementById("displayWidthPixels").value;
var h_input_str = document.getElementById("displayHeightPixels").value;
var d_input_str = document.getElementById("screenDiagonalInches").value;
var w_input = parseFloat(w_input_str);
var h_input = parseFloat(h_input_str);
var d_input = parseFloat(d_input_str);
var resultSpan = document.getElementById("result").querySelector("span");
var calculated_width = NaN;
var display_value = "N/A"; // The value to put inside the span
// Validation: Height and Diagonal must be valid positive numbers for calculation
if (isNaN(h_input) || h_input <= 0) {
display_value = "Enter valid Height (px)";
} else if (isNaN(d_input) || d_input 0) {
// User provided Width, use it to determine AR (W:H)
// This means the aspect ratio is defined by the user's entered width and height
AR_ratio_w = w_input;
AR_ratio_h = h_input;
// Calculate width based on this AR and provided height.
// This recalculates width from height using the derived AR,
// which should be very close to the input w_input if inputs are consistent.
calculated_width = h_input * (AR_ratio_w / AR_ratio_h);
} else {
// User did NOT provide Width, use default AR (16:9)
// This calculates width assuming a standard 16:9 aspect ratio for the given height.
AR_ratio_w = 16;
AR_ratio_h = 9;
calculated_width = h_input * (AR_ratio_w / AR_ratio_h);
}
// Check for invalid calculation results (e.g., from division by zero if h_input was somehow 0 after parsing)
if (isNaN(calculated_width) || !isFinite(calculated_width)) {
display_value = "N/A";
} else {
display_value = calculated_width.toFixed(2) + " px";
}
}
resultSpan.innerHTML = display_value;
}