Can I use the $30 tmobile plan with an unlock iphone 5?

I have an unlock iphone 5 and I was wondering if I could use the $30 tmobile plan with it. Also I can, would I have to cut the sim to nano?

You can use any plan from any GSM (sim card) provider with any unlocked phone, including the iPhone 5. As far as your sim card is concerned, I wouldn't even bother cutting it up. T-mobile sells micro-sims for unlocked phones. See the source below. To answer your question, yes you would have to cut your sim if you wanted to use it in the iPnone 5. Hope this helps.