How to reduce a photo's size in KB for an online form

To reduce a photo’s size in KB, change two things in this order: the pixel dimensions first, then the JPEG quality. Set the pixels to the size the form asks for, such as 200 x 230, or crop and shrink a phone photo to a few hundred pixels across, then lower the quality only until the file is under the limit. A detailed photo of about 400 x 500 pixels fits under 50 KB at good quality. Our free compress image to KB tool does both steps on your device: type the limit, add the form’s pixel size if it gives one, and download a JPG that fits.

Which tool for which limit

The form asks for	Use	What it does
Under 10, 15, 20, 30, 40 or 50 KB	10 KB, 15 KB, 20 KB, 30 KB, 40 KB, 50 KB	The limit is set, with buttons for common form pixel sizes
Under 100, 200 or 500 KB, or 1 MB	100 KB, 200 KB, 500 KB, 1 MB	Keeps as many pixels as the limit allows
Any other limit	Compress image to KB	Type any number in KB or MB
A range such as 20 to 50 KB	20 to 50 KB, 50 to 100 KB	Stays above the minimum and below the maximum
A signature of 10 to 20 KB	Resize signature	Whitens the paper and fits the range
A size in cm, a DPI and a KB limit	Resize image in cm and KB	Turns centimeters into pixels at the DPI you set
A minimum your file is below	Increase image size in KB	Raises the JPEG quality, never pads the file
A PDF under 100, 200, 300 or 500 KB, or 1 MB	100 KB, 200 KB, 300 KB, 500 KB, 1 MB	Photos or scans in one PDF under the limit
An iPhone HEIC photo the form refuses	HEIC to JPG	Real JPG copies, which you can then compress

All of these run in your browser, so your photos, signatures and documents are not uploaded.

What KB means and why forms limit it

A kilobyte (KB) is 1,000 bytes in the metric sense, or 1,024 bytes in the older binary count. NIST notes that computer professionals long used the prefix kilo to mean 1024 (NIST), and websites still use both. A phone photo is often 3 to 10 MB, so getting it under a 50 KB limit means making it 60 to 200 times smaller.

Because of the two ways of counting, a file of 50,100 bytes passes a 50 KB limit counted in 1,024s (51,200 bytes) but fails one counted in 1,000s. Aim under the smaller number. Our tools keep a file under a maximum counted in 1,000s and above a minimum counted in 1,024s, so it passes either way.

The notices we read do not say why they set these limits. They are clear about what they want: a clear, recent face, a legible signature, and a file of a set type and size. The IBPS bank notice says the system will not let you move to the next stage of the application until the photo and signature meet its specifications (IBPS). Some forms also set a minimum, so a tiny thumbnail cannot pass either.

The two levers: pixel size and JPEG quality

File size comes from two settings:

• Pixel dimensions. Halving the width and the height leaves a quarter of the pixels, and roughly a quarter of the data.
• JPEG quality. A lower quality throws away fine detail the eye notices least, and the file shrinks. Push it too low and square blocks appear around edges, text and skin.

In our tests, a detailed photo saved as a good-quality JPG came to about:

Pixel size	File size at good JPEG quality	Fits under
300 x 375	about 20 KB	30 KB
400 x 500	about 40 KB	50 KB
600 x 750	about 85 KB	100 KB
800 x 1000	about 150 KB	200 KB

Photos with a plain background, such as passport photos, come out smaller. A signature on white paper is smaller still.

Use the two levers in this order:

1. Crop to what matters: your head and shoulders, or the signature. Background costs bytes and adds nothing.
2. Set the pixel size the form names. If it names none, shrink the photo to around the size in the table for your limit.
3. Lower the quality only as far as you need. Our tool searches for the highest quality that fits, and with Keep or shrink it makes the picture slightly smaller rather than letting the quality drop so low that it breaks up.
4. Save as JPG unless the form lists other formats. PNG keeps every pixel exactly, so photos stay large: our 300 x 375 test portrait was 209 KB as a PNG and 13 KB as a JPG at quality 80.

Changing the DPI does not help. It is one number in the file header, worth a few bytes; our DPI guide explains what it does.

Photo and signature limits on official forms

These are the rules in official notices and pages we read on 9 November 2026. Every recruitment cycle can change them, so check the notice for your own application.

Form	Photo	Signature and other files
IBPS PO/MT-XVI, bank recruitment, 2026 notice (IBPS)	JPG, 20 to 50 KB, 200 x 230 pixels preferred, plus a live photo taken by webcam or phone	Signature 10 to 20 KB, 140 x 60 pixels preferred. Left thumb impression 20 to 50 KB, 240 x 240 pixels in 200 DPI. Handwritten declaration 50 to 100 KB, 800 x 400 pixels in 200 DPI. 10th certificate as an A4 PDF up to 500 KB
SSC Combined Graduate Level 2026 (SSC)	Captured live by the application; a photo of an existing photo gets the application rejected	Signature JPEG or JPG, 10 to 20 KB: about 6.0 x 2.0 cm (width x height) in the notice text, 4.0 x 2.0 cm in its application form instructions
UPSC Civil Services 2026 (UPSC)	Upload a photo and also capture a live photo; the notice points to the instructions on upsconline.nic.in	Sign three times, one below the other, in black ink on plain white paper, and upload it
Indian passport (Passport Seva)	Color, 630 x 810 pixels	Embassies set the KB limits: the Embassy of India in Paris says generally up to 200 KB for the photo and up to 100 KB for the signature, as JPG (Embassy of India, Paris)
Indian e-Visa (Government of India)	JPEG, 10 KB to 1 MB, height and width equal	Passport page as a PDF of 10 KB to 300 KB
UK passport, online (GOV.UK)	At least 600 x 750 pixels, 50 KB to 10 MB, unaltered by computer software	None

Two details trip people up. The IBPS photo section is headed 4.5 cm x 3.5 cm but asks for 200 x 230 pixels, and at 200 DPI a 3.5 x 4.5 cm photo would be 276 x 354 pixels. A file has no centimeters of its own, only pixels, so use the pixel size. And SSC gives the signature in centimeters with no DPI, and two different widths in the same notice: at 200 DPI, 6.0 x 2.0 cm is 472 x 157 pixels and 4.0 x 2.0 cm is 315 x 157 pixels. Both are written as approximate sizes, while the 10 to 20 KB file size is stated the same way each time; resize image in cm and KB works out the pixels for you.

GOV.UK also says not to crop a photo you take on your own device during the application, because the service crops it for you. For passport and visa photos in other countries, see our passport photo size guide. For state commissions, universities and other recruiters, the limits are in each notice; if your notice gives a size we do not list here, type it into the tool.

How to compress a photo to a size in KB with our tool

1. Open compress image to KB, or the page for your size, and choose your photo. It takes JPG, PNG, WebP, AVIF or GIF files, up to 30 at once.
2. Tap a target such as 20 KB, 50 KB or 100 KB, or type the number in Max. If the form sets a range, type the lower number in Min.
3. Under Dimensions, leave Keep or shrink on if the form gives no size. If it does, choose Exact size and type the width and height in pixels, cm or inches. If the shape differs offers Crop to fill or Fit inside, add white.
4. Leave Format on JPG, and set DPI only if the instructions name one.
5. Download the file. The result line shows the final size, the pixels and the quality used, and the file name ends with its size in KB.
6. To double-check, drop the file into Check my file under the tool. It shows the size counted both ways a site may count a kilobyte, the pixels, the DPI stored in the file and the real format, each marked pass or fail against your limits.

The photo is compressed by your browser on your device and is not sent to uncrop.si. With Keep or shrink, a photo over 16 megapixels is first scaled to 16 megapixels. With Exact size, the pixels never change, so a large exact size can force a low quality: if the result looks blocky, choose a smaller size the form allows.

For a signature, the signature resizer is the same tool set to 10 to 20 KB with Whiten the paper on. That turns gray paper white and the ink solid, and it also makes the image black and white, so untick it if the form wants to see blue ink. To cut a signature out onto a clear background for documents, see our guide on how to make a signature transparent.

How to reduce photo size on iPhone and Android

iPhone

Our tool works in Safari: open the page, tap Choose images, pick the photo and download the JPG. If a form refuses your iPhone photos because they are HEIC files, Apple’s setting for new photos is Settings > Camera > Formats > Most Compatible, which saves new photos and videos as JPEG and H.264 (Apple). For photos you already took, HEIC to JPG makes JPG copies on the phone, and you can then compress them.

Samsung Galaxy

The Gallery app can shrink a photo by a percentage:

1. Open Gallery and select the photo.
2. Tap the Edit icon at the bottom of the screen.
3. Tap More options (the three vertical dots) at the top right, then Resize.
4. Choose a percentage, tap Done, then tap Save. To keep the original, tap More options, then Save copy instead (Samsung).

Samsung says you cannot resize a photo to larger than its original size, and that some models do not have the feature. It sets a percentage, not a size in KB, so you may still need a KB tool afterwards.

Google Photos

Google’s editing help lists crop, rotate, aspect ratio, filters, adjustments and markup, but no way to resize a photo or set its file size (Google). Storage saver is not one either. It is the backup quality for the copies Google Photos stores: Google says they are kept at slightly reduced quality, photos over 16 MP are resized to 16 MP, and they may be converted to JPG (Google). A 16 MP photo is still far bigger than a 50 KB form limit, so use a KB tool in Chrome instead.

How to reduce photo size on a Mac or a Windows PC

Mac: Preview

1. Open the photo in Preview and choose Tools > Adjust Size.
2. Keep Resample image selected, then enter a smaller width and height, or a smaller value in Resolution. Apple says the new size appears at the bottom of the window (Apple).
3. Choose File > Export, choose JPEG in the Format pop-up menu, and adjust the quality. Apple says you can adjust the image’s quality when you choose JPEG (Apple).
4. Type a name and click Save, then check the file size before you upload it.

Preview has no box for a target size in KB, so you may need a couple of tries. Our browser tool works in Safari on a Mac too, and it finds the quality for you.

Windows

The Microsoft help pages we checked do not describe resizing or compressing a photo in the Photos app or Paint, so we do not give menu steps for them here. The IBPS notice itself suggests MS Paint for saving a scan as a JPG with Save As and adjusting the size with crop and resize (IBPS). Our compress image to KB tool runs in Edge or Chrome on Windows with nothing to install, and it shows the final size before you upload.

When a form needs a minimum size in KB

A minimum, such as 20 KB for the IBPS photo or 50 KB for a UK passport photo, catches files that are too small. There are honest ways to make a file bigger:

• Save it again at a higher JPEG quality, with the same pixels. In our tests a 200 x 230 photo grew from 7.2 KB to 30.2 KB at quality 100.
• Use more pixels, if the form accepts other dimensions, or start again from the original photo rather than a copy that was already shrunk.
• Save a PNG, but only if the form accepts PNG.

Our increase image size in KB tool raises the quality first and keeps the pixels. If quality 100 is still short, it suggests the pixel size that would pass, and applies it only if you tick Allow a larger pixel size. It never adds filler bytes. A higher quality stores the same pixels more exactly; it does not make a blurry photo sharper.

Signatures are the usual problem, because they are mostly blank paper. Our 140 x 60 test signature reached only 8.5 KB at full quality, under a 10 KB minimum, and passed at 166 x 71 pixels with 11.5 KB. IBPS marks 140 x 60 as preferred, not fixed, so a slightly larger size is the honest fix.

How to make a PDF under a KB limit

Some forms want documents as PDF files. IBPS asks for the 10th certificate as an A4 PDF of up to 500 KB (IBPS), and India’s e-Visa form for the passport page as a PDF of 10 KB to 300 KB (Government of India).

Our JPG to PDF pages set the limit for you: under 100 KB, 200 KB, 300 KB, 500 KB or 1 MB. In our tests, 100 KB held one A4 page sharply, at about 1,400 pixels on the long side, or two pages that were still easy to read, and 200 KB held about five pages. Crop each photo to the edge of the paper first, and turn a black and white page black and white, so the limit goes to the text rather than the table and the color tints.

Common upload errors and how to fix them

Error or problem	Likely cause	Fix
File size exceeds the limit, though your computer shows it just under	The site counts 1 KB as 1,000 bytes, your computer as 1,024	Aim under the limit in 1,000s; our tools do this automatically
File size is below the minimum	Too few pixels, or a very plain image	Increase image size in KB, or use a larger pixel size if the form allows
Invalid dimensions, or the photo must be 200 x 230	The pixels do not match the form	Exact size in the compressor; crop to the right shape first so the face is not stretched
Invalid file type with an iPhone photo	The photo is HEIC	HEIC to JPG, or Most Compatible in the Camera settings for new photos
Invalid file type after renaming .png to .jpg	Renaming does not convert the file	Make a real JPG with PNG to JPG, or let the compressor save one
The photo looks blurry or blocky after compressing	Too many pixels for the KB, so the quality fell too low	Use a smaller pixel size, crop closer and use a plain background
The signature is rejected or looks faint	Gray paper, faint ink, or a signature in capital letters	Resize signature with Whiten the paper; IBPS does not accept signatures in capital letters
SSC rejects the photo	A photo of an existing printed photo was captured	Take a fresh live photo in the application, as the SSC notice requires
The PDF is too big	Large page photos	JPG to PDF under 100 KB or a larger limit

If the upload still fails, open the file in Check my file on the compress image to KB page and compare each line with your notice. The pixel size, the file size both ways, the DPI and the real format are all listed, so the rule you are missing is usually plain to see.