How this instrument works
Resolution scale expresses one pixel resolution as a percentage of another. It's a single-dimension comparison — typically run on width, since width and height usually scale together at a fixed aspect ratio — that answers questions like 'how much bigger is 4K than 1080p?' with one clean number instead of two separate pixel counts.
The calculation divides the new resolution by the original resolution and multiplies by 100. A result of 200% means the new resolution is exactly double the original in that dimension; a result under 100% means it's a downscale, smaller than the original; exactly 100% means no change at all.
This percentage shows up constantly in display and gaming settings. Windows and macOS display scaling, GPU render-resolution sliders, and streaming quality presets are all commonly expressed as a percentage of a native or reference resolution, because a single percentage communicates the scale relationship more directly than comparing two raw pixel-count pairs.
- Enter the resolution you're scaling to into New resolution (px) — typically the width in pixels of your target or output resolution.
- Enter the resolution you're comparing against into Original resolution (px) — typically the width in pixels of your source or reference resolution.
- Read Scale (%) for the result — over 100% is an upscale, under 100% is a downscale, and exactly 100% means the two resolutions match.
- Compare heights the same way if you need to double-check a non-uniform scale, by re-running the instrument with the height values in place of the width values.
Worked example — 4K UHD compared to 1080p
Enter 3840 into New resolution (px) and 1920 into Original resolution (px) — the horizontal pixel widths of 4K UHD and Full HD (1080p) respectively. Scale (%) works out to (3840 ÷ 1920) x 100 = 200.0%.
That 200% result confirms the well-known relationship between the two standards: 4K UHD is exactly double the horizontal (and vertical) resolution of 1080p, which is why upscaling 1080p footage or a 1080p render to fill a 4K display is a clean 2x scale rather than an awkward fractional one.
Questions
What does a scale of 150% mean in display or game settings?
It means the resolution you're comparing to is one and a half times the width (and, at a fixed aspect ratio, the height) of your reference resolution. In Windows display scaling or a game's render-resolution slider, a 150% setting relative to your monitor's native resolution renders more pixels than the screen has, then downsamples the result — often used to improve edge and texture sharpness at some performance cost.
Why is 4K exactly 200% of 1080p rather than some other number?
Because the two standards were deliberately defined with that clean doubling relationship: 3840x2160 is exactly twice the width and twice the height of 1920x1080. That doubling means every 1080p pixel maps cleanly onto a 2x2 block of 4K pixels, which is one reason upscaling 1080p content to 4K displays, or rendering games at 1080p internally before upscaling to a 4K output, tends to look cleaner than a non-integer scale factor would.
Is a resolution scale below 100% the same as compression?
No — they're different operations. A resolution scale below 100% means the image genuinely has fewer pixels, reducing detail that generally can't be recovered. Compression, by contrast, keeps the same pixel count but reduces file size by discarding or approximating redundant information, which can also reduce visible quality but through a different mechanism entirely.
Should I compare width or height when checking resolution scale?
Width is the conventional choice, and it's sufficient whenever both resolutions share the same aspect ratio, since width and height then scale together proportionally. If you suspect the aspect ratio differs between the two resolutions — say, comparing a 16:9 resolution to an ultrawide 21:9 one — check both width and height separately, because the scale percentage may not match in each dimension.
How does this relate to GPU render-resolution or supersampling settings?
Many games expose a render-resolution or resolution-scale slider expressed as a percentage of your display's native resolution — exactly the value this instrument calculates. Setting it above 100% renders more pixels than your screen has (supersampling) for sharper edges at a performance cost; setting it below 100% renders fewer pixels than native (dynamic resolution or performance mode) to improve frame rate at some cost to sharpness.