A patchy tan can have a few different causes. If you’re using a sunless tanning product, it could be that you didn’t apply it evenly. It could also be that the product itself is of poor quality and doesn’t give an even coverage. If you’ve been in the sun or on a sunbed, it could be that you burned in some areas but not others. That’s because your skin produces more melanin when it’s damaged by overexposure to UV rays, so the skin that was burned will be darker than the skin that wasn’t. Finally, it could simply be that your natural skin colour is uneven – some people have patches of skin that are darker or lighter than the rest of their body.