Exporting by exact pixel dimensions is the standard way to get images out of Lightroom Classic. If you need a web header that is exactly 2000 pixels wide, you set the width and move on.
But setting a strict dimensional width or height limit in pixels causes problems when you’re exporting a large batch of images cropped to different aspect ratios. If you have a mix of square crops, 16:9 panoramas, and standard 4:3 images, exporting them all at “3000 pixels wide” will result in wildly different total file weights and visual sizes. In other words, a mess.
That’s where Lightroom’s target megapixel feature comes in. By setting a megapixel limit (abbreviated as MP) rather than a dimensional limit, you tell Lightroom to equalize the total area of the image, regardless of its shape.
And it’s a simple but useful feature that’s already baked into Lightroom Classic’s export panel. Here’s how to set it up.
How to set a megapixel limit in Lightroom
This feature is built directly into the standard export menu.
- Select your images and open the Export dialog.
- Scroll down to the Image Sizing panel.
- Check the box for Resize to Fit.
- Click the drop-down menu and select Megapixels.
- Enter your target number in the box.
Note: I highly recommend also checking the “Don’t Enlarge” box. This ensures Lightroom doesn’t accidentally upscale a heavily cropped photo just to meet your target limit, which would degrade the final image quality.
Why use megapixels instead of pixels?
I rarely use this for standard web publishing, but there are two specific scenarios where this mathematical approach to exporting saves a lot of time.
- Submitting to Stock Photography Agencies. Most stock agencies don’t care about the exact width or height of an image; they care about the total resolution. That makes it far easier for them to manage multiple different aspect ratios produced by different cameras and cropping in editing. They almost always mandate strict minimum or maximum megapixel requirements. Dialing in a specific MP limit lets you batch-export an entire catalog of varied crops and guarantee every single file meets the agency’s baseline requirement, without having to do the math for each individual frame.
- Managing Massive Files for Client Proofs. If you’re shooting with a high-resolution camera, exporting full-resolution JPEGs just for a client review gallery is a waste of time and bandwidth. Dialing the export down to a comfortable 5MP or 10MP limit yields files that look perfectly sharp on a monitor or tablet, but are small enough to upload quickly to a web gallery or send via email without clogging up inboxes. It’s a fast way to normalize a massive shoot into a manageable, uniform package.
