Can I upscale a low-resolution photo for a large print?

Yes, for most real printing situations — a 12-megapixel file upscaled to fill a large print, then hung and viewed the way large prints actually get viewed, holds up convincingly well in practice, not just in theory.

For the full reasoning behind why viewing distance, not raw pixel count, is what actually determines this, see upscaling as a real tool with real limits.

Where Upscaling Genuinely Works Well

A 12-megapixel file destined for a large wall print viewed from several feet back is a strong candidate — the required pixel density at that distance is already modest, and upscaling comfortably bridges whatever gap remains between the file's native resolution and the print's pixel dimensions, with the software-added detail never being scrutinized closely enough to reveal its artificial origin.

Where It Genuinely Has Limits

Upscaling can't recover detail that was never captured in the first place — a soft, out-of-focus, or heavily noise-reduced source file will upscale into a larger, still-soft or still-artifact-laden image, not a genuinely sharper one. It's also less forgiving for prints meant to be examined closely, where the gap between real captured detail and software-inferred detail becomes more apparent the closer a viewer actually gets. A test print of a small section at full size, before committing to the full print run, is a cheap way to confirm the result actually holds up before spending money on the larger piece.

Check exactly how large your native (un-upscaled) resolution supports before deciding how much upscaling you actually need in the Print Size / DPI Calculator, pre-filled at 12 megapixels.