How to find out when my mobile contract ends?

I have a 24 month contract with three for my iPhone 5, and I'm sure i will be at 24 months next month. But how do I find out. I want to cancel my contract and go with a cheaper one, as I'm paying upto. £40 a month now

Go to the website of your carrier, and log in. I think you'll find out there! I know I've got an app for mine telling me my usage and extras, and when I can upgrade/ runs out.that's with Vodafone! So have a look on your app store and see if your carrier has an app too! It may be on there.