Aspect Ratio Calculator
Resize while keeping proportions exact.
Enter your values
Enter the original width in px.
Enter the original height in px.
Enter the new width in px.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- New height
- 720 px
- Aspect ratio
- 16:9
- Decimal ratio
- 1.7778
- Scale factor
- 0.6667×
Working
- 1h₂ = 1280 × 1080 ÷ 1920 = 720 px
Quick answer
To keep an aspect ratio, scale both dimensions by the same factor: new height = new width × original height ÷ original width.
h₂ = w₂ × h₁ ÷ w₁
At a glance
| What it does | Resize while keeping proportions exact. |
|---|---|
| Category | Conversions |
| Inputs needed | Original width, Original height, New width |
| Main output | New height |
| Formula | h₂ = w₂ × h₁ ÷ w₁ |
| Cost | Free — no sign-up, no download |
How to use the Aspect Ratio Calculator
- 1Enter the original width and height.
- 2Enter the new width you want.
- 3Read the height that keeps the proportions.
Inputs explained
- Original width(px)
- Enter the original width in px.
- Original height(px)
- Enter the original height in px.
- New width(px)
- Enter the new width in px.
Worked example
Using the values the calculator loads with:
Inputs
- Original width1920 px
- Original height1080 px
- New width1280 px
Results
- New height720 px
- Aspect ratio16:9
- Decimal ratio1.7778
- Scale factor0.6667×
- h₂ = 1280 × 1080 ÷ 1920 = 720 px
Frequently asked questions
What is 16:9 in pixels?
Any size where width ÷ height is 1.778 — 1920×1080, 1280×720 and 3840×2160 are all 16:9.
Why does my image look squashed?
Because width and height were scaled by different factors. Always scale both by the same amount.
What do I need to enter into the Aspect Ratio Calculator?
Just 3 values: original width, original height, new width. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Aspect Ratio Calculator work out the answer?
To keep an aspect ratio, scale both dimensions by the same factor: new height = new width × original height ÷ original width. It applies the formula h₂ = w₂ × h₁ ÷ w₁ and shows the working so you can check each step by hand.
Is the Aspect Ratio Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.