Aspect Ratio Calculator
Type your original width and height. Then change either the new width or the new height — the other side updates automatically to preserve the original aspect ratio. Use this before Ctrl+Alt+I (Image Size) inside Photoshop 7.0 so you know exactly which dimensions to type in.
Calculate
Tip: change one of the "new" fields and the other will update.
How Photoshop 7.0 Handles Aspect Ratios
Photoshop 7.0's Image Size dialog (Image → Image Size, shortcut Ctrl+Alt+I) has a "Constrain Proportions" checkbox at the bottom. When it is on — and it should be on for almost every resize — typing a new width automatically updates the height. The Aspect Ratio Calculator above does exactly the same maths, but lets you compute it before opening the dialog so you can plan your final output dimensions ahead of time.
The other Photoshop 7.0 dialog where aspect ratio matters is the Crop tool options bar. With the Crop tool active, you can type a fixed Width, Height, and Resolution into the options bar before drawing the crop rectangle — Photoshop will constrain the rectangle to that aspect ratio. Combine this with our calculator to plan crops for print or social-media output.
The Maths (in case you are curious)
Aspect ratio is simply width divided by height. To resize without distortion:
new_height = new_width × (original_height / original_width)
new_width = new_height × (original_width / original_height)So a 1920×1080 image (ratio 1.778) resized to a new width of 1280 produces a new height of 1280 × (1080 / 1920) = 720. That is the same result Photoshop 7.0 computes internally — but doing it ahead of time lets you decide on the exact number you want.