Pixel Ratio Calculator
The Pixel Ratio Calculator converts between CSS pixels and physical (device) pixels using the device pixel ratio (DPR). Calculate the actual rendered resolution on Retina and HiDPI displays, and determine optimal image sizes for crisp rendering.
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What is Pixel Ratio?
Device pixel ratio (DPR) is the ratio of physical pixels to CSS pixels on a display. A DPR of 2 (Retina) means each CSS pixel is rendered using a 2×2 grid of physical pixels. A 375×812 CSS viewport on an iPhone at 3× DPR actually renders 1125×2436 physical pixels.
Understanding DPR is essential for web developers to serve appropriately sized images. A 200×200 CSS image needs a 400×400 source file for 2× displays and 600×600 for 3× displays to appear crisp. Without accounting for DPR, images appear blurry on high-density screens.
Fórmulas y Ecuaciones Utilizadas
Esta Pixel Ratio Calculator utiliza 5 ecuaciones principales:
1 Physical Pixels from CSS ▼
A 375px CSS width at 3× DPR: Physical = 375 × 3 = 1125 physical pixels.
2 CSS Pixels from Physical ▼
A 2560×1440 display at 2× DPR renders as 1280×720 CSS pixels.
3 Image Size for Target DPR ▼
A 300×200 CSS image area needs 600×400 source for 2× DPR, 900×600 for 3× DPR.
Cómo Usar esta Calculadora
Para usar esta Calculadora de Relación, siga 3 pasos:
Ingrese los Valores
Escriba los valores de relación conocidos en los campos de entrada. Deje un campo vacío; ese es el valor desconocido que resuelve la Calculadora de Relación.
Elija el Modo
Seleccione el modo de relación: Resolver, Simplificar o Escalar. Cada modo aplica diferentes ecuaciones a sus valores de entrada.
Obtenga Resultados
Haga clic en Calcular. La pantalla de resultados muestra la respuesta con una barra de relación visual, un gráfico circular y un desglose de la solución paso a paso.
Problemas de Ejemplo y Soluciones Paso a Paso
Aquí hay 3 problemas de ejemplo con soluciones paso a paso usando esta Calculadora de Relación:
Entrada 1 iPhone 14 Pro: 393×852 CSS at 3× DPR
Entrada 2 Image for 2× and 3× displays
Entrada 3 Calculate DPR from screen specs
Preguntas Frecuentes
What is device pixel ratio (DPR)? ▼
DPR is the ratio between physical display pixels and CSS (logical) pixels. DPR 1 = standard displays. DPR 2 = Retina/HiDPI (Apple, many laptops). DPR 3 = high-end phones (iPhones, Samsung flagships).
How do I find my screen's pixel ratio? ▼
In a browser, open the console and type window.devicePixelRatio. Common values: 1 (standard monitors), 1.25 or 1.5 (Windows scaling), 2 (MacBook Retina), 3 (iPhone Pro).
Why do images look blurry on Retina displays? ▼
A 200×200 pixel image displayed at 200×200 CSS on a 2× DPR screen is stretched to 400×400 physical pixels, causing blur. The solution: use a 400×400 source image to match the physical pixel count.
How does pixel ratio affect website performance? ▼
Higher DPR images are larger files (4× file size at 2× DPR). Use responsive images (srcset attribute) to serve appropriately sized images based on DPR, balancing quality and page load speed.
What is the pixel ratio for 4K monitors? ▼
A 4K (3840×2160) monitor at native resolution has DPR 1.0. With Windows scaling at 150%, effective DPR ≈ 1.5. At 200% scaling (common on 27" 4K), DPR = 2.0, rendering content at 1920×1080 CSS pixels.