United Kingdom passport photo size & rules
British passport photos follow the standard European 35x45mm rectangle, which at 300 dpi corresponds to 413x531 pixels. HM Passport Office is unusually specific about the head size: the measurement from the bottom of your chin to the crown of your head must be between 29mm and 34mm. That is a tighter window than many other countries allow, and photos where the face is too small or too large are the single most common reason UK applications are held up.
The background should be plain light grey or cream, and crucially it must contrast with your face and clothing so the outline of your head is clearly defined. The UK does not accept pure white in the same way the United States does. Look straight at the camera with a neutral expression and your mouth closed, both eyes open and clearly visible, with nothing covering your face. Glasses are discouraged and should be avoided if possible; if you must wear them, your eyes must be clearly visible with no glare or heavy frames obscuring them. If you apply online, you can submit a digital photo directly, and the same 35x45mm proportions apply.
Pixohub crops and formats your UK passport photo to 413x531 pixels completely in the browser, so your image never leaves your device, which matters for a sensitive identity document, and the service is free. Requirements set by HM Passport Office are updated from time to time and the automated digital-photo checker can be strict. Always review the current guidance on gov.uk before you order prints or upload your image to make sure it will pass first time.