Your passport photos are an essential part of your application. Inappropriate photographs you submit will cause a delay in processing your passport. Sometimes you might have to go through the whole process twice and thrice if your passport image is not legally compliant. Kindly follow the instructions below so that you get it right the first time.

Requirements:

• You have to get a new passport photo for the passport even if your appearance has not changed a bit.
• Your passport photo must have recently been taken. It must have been taken in the previous 30 days.
• If your images don't comply with the requirements, your application will be postponed.
• If you have a disability, you can request assistance with your UK passport photos. 

Passport Image Size 

• The photo must be the standard size for photo booths in the UK, which is 45 millimetres high by 35 millimetres wide 
• If you are outside the UK, not all photo booths use this standard size. So, make sure to cross-check the size before getting the image.
• It shouldn't be cropped or reduced in size from a larger photo to fit an acceptable passport photo.
• Your image - from the crown of your head to your chin - must be between 29mm and 34mm high.

The quality of your printed photos

Your photos must be:

• photographed against a plain light grey or cream background.
• printed with high quality, such as by a studio or photo booth (home printing of photos is unlikely to yield results of sufficient quality);
• clear and in focus
• in colour on plain white photographic paper with no border
• without any creases or tears
• unmarked on both sides (unless a photo needs to be countersigned)
• unaltered by computer software

Photo style  

You must be:

• facing the camera and maintaining eye contact
• be a close-up of your full head and upper shoulders, with a suggested head height of between 29 and 34 millimetres (the space between the bottom of the chin and the top of the head).
•  have a  neutral expression and mouth must be closed (no laughing, frowning, or raised eyebrows);
• with their eyes open and plainly visible (no tinted or sunglasses, and no eyebrows or facial hair in the area of the eyes);
• free from reflections or glare on glasses, and frames must not conceal eyes (we advise taking off glasses for the shot, if at all feasible).
• show your entire head (unless it’s covered due to medical or religious reasons)
• without any other persons or items in the picture (babies shouldn't have toys or dummies in pictures of them, and this rule also applies to pictures of young children).
• free of shadows on the image.
• without anything concealing the face; nothing should obscure the mouth, nose, or eye outlines;
• no "red-eye."

Photos of babies and children

• Children in the image must be by themselves. Babies are not allowed to grasp toys or use dummies.
• Children below the age of five are not required to look directly at the camera or have a neutral expression. 
• Children under the age of one do not require to have their eyes open. If the infant's head needs to be held high, the holding hand must be hidden. 
• All additional passport photo requirements must be fulfilled.

Note: When uploading your images for your application, 

• you need to attach 2 identical photos.
• make sure that they are: not grouped together, or associated with your application form. The images must be let loose.

If you want to get a passport image that is accepted on the first try, then we are here to help you convert your image as per the country guidelines.

Note : The requirements are subject to change. Please check the government's official website for the most recent regulations.

Direct Link : https://www.gov.uk/photos-for-passports/photo-requirements