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Aspect Ratio Calculator

The Aspect Ratio Calculator computes the proportional relationship between width and height for displays, videos, and images. Enter any two values — width, height, or target ratio — and get the missing dimension instantly. Supports standard ratios like 16:9, 4:3, 21:9, and 1:1.

Aspect Ratio Calculator — Live Preview
Aspect Ratio
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Widgets

Quick interactive ratio calculators — solve proportions, scale values, and simplify ratios.

Proportion Solver

Provide any three values below to calculate the fourth in the ratio A : B = C : D.

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Solved Proportion
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Simplified
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Percentages
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Decimal
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Fraction
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Visual Ratio
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    Scale Multiplier

    Scale a ratio up or down by a multiplier.

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    Scaled Ratio
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    Original
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    Factor
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    Percentages
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      Simplifier

      Reduce any ratio to its simplest form.

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        What is an Aspect Ratio?

        An aspect ratio describes the proportional relationship between the width and height of a rectangle. Expressed as W : H, it tells you the shape of a screen, image, or video frame. A 16:9 aspect ratio means for every 16 units of width, there are 9 units of height — the standard for modern widescreen displays.

        Common aspect ratios include 16:9 (HDTV, YouTube), 4:3 (classic TV, presentations), 21:9 (ultrawide monitors, cinema), 1:1 (Instagram square), and 9:16 (TikTok, Stories). Maintaining correct aspect ratios prevents image stretching and distortion during resizing.

        Formulas & Equations Used

        This Aspect Ratio Calculator uses the following core equations:

        1 Aspect Ratio from Dimensions ▼
        Aspect Ratio = Width : Height (simplified by GCD)

        Divide both width and height by their GCD. 1920 × 1080: GCD(1920, 1080) = 120. Ratio = 16 : 9.

        2 Height from Width and Ratio ▼
        Height = Width × (Ratio H / Ratio W)

        Given a width of 1280 and a 16:9 ratio: Height = 1280 × (9/16) = 720 pixels.

        3 Width from Height and Ratio ▼
        Width = Height × (Ratio W / Ratio H)

        Given a height of 1080 and a 16:9 ratio: Width = 1080 × (16/9) = 1920 pixels.

        How to Use This Aspect Ratio Calculator

        Follow these 3 simple steps:

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        Enter Your Values

        Type the known values into the input fields above. The Aspect Ratio Calculator accepts any positive numbers.

        2

        Choose Calculation Mode

        Select Solve, Simplify, or Scale mode in the calculator. Each applies different equations to your inputs.

        3

        View Results

        Click Calculate to see your answer with a visual ratio bar, pie chart, and step-by-step solution breakdown.

        Example Problems & Step-by-Step Solutions

        Here are 3 worked examples using this Aspect Ratio Calculator:

        Example 1 Find aspect ratio of 2560 × 1440
        1 Find GCD(2560, 1440) = 160
        2 Width: 2560 / 160 = 16
        3 Height: 1440 / 160 = 9
        ✓ Aspect ratio is 16 : 9
        Example 2 Find height for 1920px wide at 4:3
        1 Height = Width × (H ratio / W ratio)
        2 Height = 1920 × (3 / 4)
        3 Height = 1440 pixels
        ✓ Height is 1440 pixels
        Example 3 Find width for 1080px tall at 21:9
        1 Width = Height × (W ratio / H ratio)
        2 Width = 1080 × (21 / 9)
        3 Width = 2520 pixels
        ✓ Width is 2520 pixels

        Interactive Screen Shape Preview

        Select a common aspect ratio to see how the screen shape changes visually. Click any preset to instantly see the proportional rectangle — this is exactly how displays, images, and video frames appear at each ratio.

        16 : 9
        1920 × 1080
        Widescreen — Standard for HDTV, YouTube, and modern monitors

        Common Display Resolutions by Aspect Ratio

        This reference table shows the most widely used screen resolutions grouped by their aspect ratio. Use it to quickly find the correct dimensions for your target display or platform.

        RatioResolutionNameUse Case
        16:91920 × 1080Full HD (1080p)Most monitors, TVs, YouTube
        16:92560 × 1440QHD (1440p)Gaming monitors
        16:93840 × 21604K UHDPremium displays, streaming
        4:31024 × 768XGAProjectors, legacy displays
        21:92560 × 1080UWFHDUltrawide monitors
        21:93440 × 1440UWQHDUltrawide gaming
        1:11080 × 1080SquareInstagram posts
        9:161080 × 1920PortraitTikTok, Instagram Stories
        3:22256 × 1504SurfaceMicrosoft Surface laptops

        Frequently Asked Questions

        What is the most common aspect ratio for monitors? ▼

        16:9 is the most common aspect ratio for monitors, TVs, and laptops. Common resolutions include 1920×1080 (Full HD), 2560×1440 (QHD), and 3840×2160 (4K UHD).

        How do I calculate the aspect ratio of my screen? ▼

        Divide the screen's pixel width by height, then simplify. For a 2560×1080 monitor: divide both by GCD(2560, 1080) = 40, giving 64:27 — an ultrawide ratio close to 21:9.

        What aspect ratio is best for YouTube videos? ▼

        16:9 is the standard YouTube aspect ratio. Upload at 1920×1080 (1080p) or 3840×2160 (4K). YouTube will letterbox videos with different ratios.

        What is the difference between 16:9 and 16:10? ▼

        16:9 is wider and flatter, standard for entertainment. 16:10 is slightly taller, common on productivity laptops (e.g., 1920×1200). The extra vertical space helps with documents and coding.

        How do I resize an image without changing aspect ratio? ▼

        Lock the aspect ratio in your editing software and change only one dimension. The other dimension adjusts automatically. For example, scaling a 1600×900 image to 800px wide automatically sets height to 450px.

        What aspect ratio do cinematic movies use? ▼

        Most movies use 2.39:1 (Cinemascope/anamorphic widescreen). IMAX films use 1.43:1 or 1.90:1. Standard widescreen is 1.85:1. Letterboxing appears when these ratios display on 16:9 screens.

        Learn About Ratios

        What is a ratio?

        A ratio is a comparison between two or more quantities showing the relative size of one to another. Written as A : B, it means 'for every A units of the first quantity, there are B units of the second.' For example, a ratio of 3 : 4 means for every 3 parts of A, there are 4 parts of B. Ratios are used in cooking, construction, finance, science, and everyday life.

        How do I solve a proportion?

        A proportion is an equation that says two ratios are equal: A : B = C : D. To solve for a missing value, use cross-multiplication. If D is unknown: D = (B × C) / A. This works because in equal ratios, the cross products are always equal: A × D = B × C. Our Proportion Solver does this automatically — just enter any 3 values and it finds the 4th.

        How do I simplify a ratio?

        To simplify a ratio, find the Greatest Common Divisor (GCD) of both numbers and divide each by it. For example, 24 : 36 — the GCD of 24 and 36 is 12. So 24 ÷ 12 = 2 and 36 ÷ 12 = 3, giving the simplified ratio 2 : 3. Our Simplifier automatically finds the GCD and reduces your ratio to its lowest terms.

        What is ratio scaling and when is it useful?

        Scaling a ratio means multiplying both parts by the same factor to create an equivalent, larger (or smaller) ratio. For instance, scaling 2 : 5 by a factor of 3 gives 6 : 15. This is extremely useful for recipes (tripling a recipe), construction (scaling blueprints), mixing solutions, or any scenario where you need to maintain the same proportion at a different magnitude.

        What's the difference between a ratio and a fraction?

        A ratio A : B compares two quantities to each other (part-to-part), while a fraction A/B typically represents a part-to-whole relationship. However, any ratio can be expressed as a fraction: 3 : 4 is equivalent to 3/4 = 0.75. The key difference is context — ratios compare quantities side-by-side, while fractions represent a portion of a total.