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Aspect Ratio Calculator

Simplify image proportions and resize one dimension while preserving the ratio.

Your numbers

Make it your own
Updates as you type
Simplified aspect ratio
16:9

Calculated from your inputs · rounded for display

New width1,280px
New height720px
Decimal width / height1.7778

Fractional target dimensions are shown without forced pixel rounding. Actual image dimensions must use whole pixels and can slightly change the ratio.

Your calculation, step by step

No black boxes
  1. Divide width and height by their greatest common divisor 120.
  2. Aspect ratio = 16:9.
  3. Preserve width ÷ height = 1.777778; new size = 1,280 × 720 px.

How to use this calculator

  1. Enter your own values in the labeled fields. Check the units and assumptions before comparing results. Only the fields needed for your selected calculation mode are shown.
  2. Your answer updates automatically. Review the calculation steps to see exactly how it was calculated.
  3. Copy, share, save, or download your result. Saved inputs stay on this device.

How the calculation works

New height = new width × original height / original width

The original dimensions are whole pixels. Simplification divides them by their greatest common divisor. Resizing preserves the width-to-height quotient before rounding. If the derived dimension is fractional, an image editor must choose a whole-pixel dimension, which may slightly alter the exact ratio.

A worked example

1920 × 1080 simplifies to 16:9. At a width of 1280, the matching height is 720 pixels.

Reading your result

Use the main result together with its units and supporting figures. Display values are rounded; calculations keep their underlying precision. A change in inputs or assumptions can change the answer. Compare the step-by-step working with your intended use before relying on an estimate.

Frequently asked questions

Does this crop an image?

No. It calculates dimensions only.

Can the new size be fractional?

Yes mathematically; an actual pixel image needs whole dimensions.

Sources & methodology

This calculator uses the mathematical identity and assumptions stated above. No current rates, prices, or external data are loaded. Conversion tools use international unit definitions.

Formula review: October 24, 2026. Read our methodology.