Pick an aspect ratio or a common preset, enter a width, and get the matching height. You can also round sizes to multiples of 8 or 64, which many AI image generators work best with. Everything runs in your browser.
Last updated: October 2, 2026
Preset sizes are common starting points. Platforms update their recommendations, so check their current guidelines before publishing.
What is an aspect ratio?
An aspect ratio describes the shape of an image as width compared with height. A 16:9 image is 16 units wide for every 9 units tall, whether it’s 1280 × 720 or 1920 × 1080 pixels. Choosing the right ratio before you generate an image saves you from awkward cropping later.
Why round to multiples of 8 or 64?
Many AI image models process images in blocks, so they often work best, or only work, with sizes divisible by 8 or 64. Rounding can shift the ratio very slightly; the “Actual ratio” result shows exactly what you’ll get. When a tool only offers fixed ratios, pick the closest one and crop afterwards.
Tips for AI image sizes
- Mention the ratio in your prompt too, for example “wide 16:9 frame”, so the composition fits the shape.
- Generate at a moderate size, then upscale if you need print quality.
- Leave space around the subject if the image will be cropped for different platforms.
Learn how to describe the picture itself in our guide to writing AI image prompts.