Upscale an Image to 4K Only If the Count Works

Do the division before the upload

Take the long edge you have and the 3840 you want. A 1920-pixel photo needs 2× to reach 3840. A 960-pixel photo needs 4×. A 480-pixel photo needs 8×, which is Studio, four credits, and a large amount of invented texture. If the math needs more than 8×, this tool will not get you to 4K from that file in one pass, and a second pass on the result is a way to magnify the first invention. Stop and find a larger original.

2× can be tried by a guest, and the preview can show a result whose long edge is past 3,200. The file you download on Guest or Free plan is then reduced to 3,200. That is not 4K. Pro at $12 and Studio at $29 download the full result. If 4K is the delivery, the plan is part of the definition, not a later surprise. Upload limits matter too: a guest cannot upload a 3000-pixel file (the cap is 2,000). Free plan stops at 2,560. Pro at 4,096. Studio at 8,192.

Bigjpg’s free tier, as they publish it, allows up to 3,000×3,000 and 5 MB. That is a different cap, not a 4K promise either. Their paid tiers and the rest of the comparison are on the Bigjpg page, with the figures taken from their site on 26 October 2026. We are not going to round their numbers into ours.

A 4K grid can still be a soft picture

Pixel count is not focus. A blurry 4K frame is a large blur. If the original is soft, unblur may matter more than the jump to 3840, and unblur is a guest mode. If it is noisy, denoise first so the 4K frame does not contain larger speckles. If it is a face that has already collapsed, face restore is a likeness decision you should make at 2× before you commit it to a 4K master.

Use the result as a master only when the slider is boring in the right way: edges that were there get cleaner, flat walls stay flat, and nobody grows a new earring. Then download the full file on a paid plan and leave our copy behind. It is deleted after 24 hours. Failed jobs return the credits. The subscription does not refund. Free pages show ads. Pro and Studio are ad-free.

Screens and televisions that say 4K still scale whatever you give them. A honest 1920-pixel photograph often looks better on that screen than a 3840-pixel invention. The reason to make a true 4K file is a delivery spec, a crop, or a print, not the badge on the television.

A last look at 3840

4K is a count, about 3840 on the long edge, not a quality setting. A blurry 3840-pixel frame is a large blur, and unblur may be the real mode. A guest can see a preview larger than 3,200 px and cannot download it. That cap is the product, stated here so a 4K delivery does not surprise you at the button. Pro and Studio keep the full file when the input times the scale reaches the count.

Bigjpg’s free tier stops at 3,000 px, which is not 4K either. Their number is quoted on the comparison page from 26 October 2026. Ours is 3,200 on the free download, which clears their 3,000 px free cap, and whatever the math allows on a paid plan, inside an input cap of 4,096 on Pro and 8,192 on Studio. A television that says 4K will scale a honest 1920-pixel photograph. Make a true 4K file when a spec, a crop, or a print asks for it.

What to keep beside the slider

3840 on the long edge is the usual 4K ask. 4096 is a different number and also Pro's input cap, which confuses people into thinking the plan name is the delivery. A 1920-wide file needs 2×. A 960-wide file needs 4×. Past 8×, find another original. The free download at 3,200 is not 4K. Pro and Studio keep the file when the math reaches it. A soft 4K frame wants unblur, not a badge. A noisy one wants denoise first so the speckle is not the thing you scaled. Bigjpg’s 3,000 px free cap is not this number either. Televisions scale whatever you give them. Make a true 4K master for a spec, a crop, or a print.

The decision you can defend

3840 is the count. A 1920-wide file needs 2×. A 960-wide file needs 4×. The free download at 3,200 is not that count. Pro and Studio keep the file when the multiplication lands. A soft 4K frame is still soft. Unblur or denoise before you call the grid a master.