Make a photo lighter or darker with one slider, from 0 to 200 percent. See the change live, compare with the original, and download without uploading anything.
Multiplies the red, green and blue value of every pixel by the percentage you set. At 100 nothing changes; at 150 every tone is one and a half times as bright; at 50 it is halved. Because it is a straight multiplication, dark areas move a little and bright areas move a lot, which is why very bright settings turn skies and white shirts into flat white. The preview re-renders as you drag, and holding Space shows the original underneath.
A photo taken indoors in the evening with the subject at an average pixel value of about 70 out of 255 looks muddy on a phone screen. Setting brightness to 140% lifts that average to roughly 98, which reads as a normal indoor exposure, while the darkest shadows at 20 only rise to 28 and keep their depth. The same 140% on a beach photo pushes sand already at 210 up to 255, so for bright scenes stay near 110 or use Change Exposure, which clips more gently.
Reach for this when a whole picture is simply too dark or too light and you want a quick, predictable fix: a screenshot that came out dim, a scanned page with a grey background, a product photo that needs to pop. If only the middle tones need help and the highlights are already fine, Adjust Gamma lifts midtones without touching white. If the picture is dull rather than dark, it needs Change Contrast, not brightness. If you keep going past 150% and it still looks wrong, the photo is probably underexposed by more than this tool should fix; lower the target and accept some noise.
Brightness is a percentage of the original, so 100 is no change, 0 is black and 200 is double. The chips jump to the values people actually use. The tool warns above 140% because that is where clipping usually becomes visible. Output Same keeps the file type you dropped; choose WebP for a smaller file or PNG if the image has transparency. Batch mode applies the same percentage to every file in a folder and gives you a ZIP.
Why do bright parts turn pure white? Multiplying a value that is already near 255 pushes it past the maximum, and everything above 255 is clipped to white. Lower the percentage, or use Change Exposure or Adjust Gamma, which compress highlights instead of clipping them as hard.
Does 50% mean half as bright as it looks? Numerically yes: every channel is halved. Visually it looks somewhat less than half as bright because screens and eyes are not linear. Try 70 to 80% for a picture that reads as noticeably darker but not gloomy.
Can I brighten only the shadows? Not with this tool; it moves every tone by the same factor. Adjust Gamma with a value above 1 raises shadows and midtones while leaving white alone, which is usually what people mean by brightening the shadows.
Is anything uploaded? No. The pixels are changed by your browser on your own device and the page keeps working offline once loaded.