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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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Proportion Solver
A : B = C : D — Enter any 3 values
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Results
Visual ratio breakdown
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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    Ratio Simplifier
    Reduce any ratio to its simplest form
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    Simplified Result
    Reduced to lowest terms
    Simplified Ratio
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    GCD Used
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    Percentages
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    Decimal Ratio
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    Fraction
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    Visual Ratio
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      Ratio Scaler
      Multiply a ratio by a scale factor
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      Scaled Result
      Ratio after scaling
      Scaled Ratio
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      Original
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      Factor
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      Percentages
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      Simplified
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      Visual Ratio
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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:

        1

        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

        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.

        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.