Calculating your new height (keeps aspect ratio) is straightforward once you know the Image Resize Dimensions formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Image Resize Dimensions Calculator.
What is Image Resize Dimensions?
The Image Resize Dimensions calculation tells you your new height (keeps aspect ratio) from a few simple inputs. The figure you are solving for here is the new height (keeps aspect ratio).
The Image Resize Dimensions formula
The core formula is:
New height (keeps aspect ratio) = New width × Original height ÷ Original widthHere is what each input means:
- Original width — a value measured in px. Example: 1,920 px.
- Original height — a value measured in px. Example: 1,080 px.
- New width — a value measured in px. Example: 1,280 px.
How to calculate it step by step
- Write down the original width (for example, 1,920 px).
- Write down the original height (for example, 1,080 px).
- Write down the new width (for example, 1,280 px).
- Apply the formula above to get your new height (keeps aspect ratio).
- Double-check the result with the Image Resize Dimensions Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Original width | 1,920 px |
| Original height | 1,080 px |
| New width | 1,280 px |
| New height (keeps aspect ratio) | 720 |
With original width of 1,920 px, original height of 1,080 px and new width of 1,280 px, the new height (keeps aspect ratio) works out to 720.
Example 2
With original width of 3,800 px, original height of 1,080 px and new width of 1,280 px, the new height (keeps aspect ratio) works out to 364.
| Result | Value |
|---|---|
| New height (keeps aspect ratio) | 364 |
Example 3
With original width of 960 px, original height of 1,080 px and new width of 1,280 px, the new height (keeps aspect ratio) works out to 1,440.
| Result | Value |
|---|---|
| New height (keeps aspect ratio) | 1,440 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Image Resize Dimensions Calculator does it instantly, for free, with the formula and a worked example built in.
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