How to reduce a photo to 20 KB (or any KB limit) for exam forms

What “20 KB” actually measures

KB stands for kilobytes — a measure of how much storage the image file takes up, not how big the picture looks on screen. Two photos can show the same face at the same dimensions and still have very different file sizes, because file size depends on three things: the pixel dimensions (say 200 × 230), the amount of detail and colour in the image, and how hard the file is compressed. When a form asks for “10–50 KB”, it is telling you how small the stored file must be — and you control that mostly through dimensions and compression.

Why your photo is far too big

Phone cameras capture 12, 48 or even 108 megapixels. A single photo can be several thousand pixels wide and packed with detail, which is wonderful for printing but wildly oversized for a passport box on a web form. The exam only needs a small image — often around 200 × 230 pixels — so most of that data is wasted. Shrinking the picture to the size the form actually wants is what makes the file small, and it does so without hurting the quality you can see at that size.

Step 1: resize to the required dimensions first

Before touching quality, resize the image to the pixel dimensions the exam specifies. This single step usually removes 90–95% of the file size, because you are literally throwing away pixels the form will never display. If the exam gives dimensions in millimetres (for example 35mm × 45mm), it is describing a print size; convert it to pixels using the DPI the form states — we cover that in our photo size requirements guide.

Step 2: compress to hit the exact KB target

After resizing, JPEG compression does the fine-tuning. JPEG has a “quality” setting from roughly 1 to 100: lower quality means a smaller file. The trick is that a face at 200 × 230 pixels still looks perfectly clean at quality levels that produce a tiny file. Rather than guess, our tool runs a binary search on the quality setting — nudging it up and down until the file lands just under your KB limit while keeping the picture as sharp as that limit allows. That is why you can ask for “under 20 KB” and get a result at, say, 18 KB rather than a needlessly degraded 6 KB.

Step 3: keep the format the exam asks for

Most exams want a JPG/JPEG photo. JPEG is ideal here: it compresses photographs efficiently and every portal accepts it. Avoid PNG for photos — it does not compress faces well and produces much larger files at the same dimensions. If your phone saved the picture as HEIC (common on iPhones), convert it to JPEG first, because many Indian portals silently reject HEIC. Our tool converts HEIC automatically as part of the resize.

Common mistakes that keep the file too big

• Cropping without resizing. Cropping changes what is in the frame but often leaves the pixel dimensions huge. Always resize to the target pixel size, not just crop.
• Screenshotting the photo. A screenshot re-saves the image at your screen's resolution and can make it larger, not smaller.
• Compressing an already-tiny image again. Running a 15 KB file through another heavy compression only adds visible blocky artefacts. Start from the original and resize once.
• Uploading a PDF or document. The photo field wants an image file (JPG/PNG), never a PDF.

Do it in your browser, privately

You do not need to install an app or email your photo to a website. Exam Photo Toolkit resizes and compresses entirely inside your browser — your image never leaves your phone or computer. Pick your exam, and the tool applies that exam's exact dimensions and KB limit for you, so you do not have to memorise the numbers. Browse your exam on the home page to get a photo that fits the first time.