According to wikipedia: 4.37 light-years (about 41.5 trillion km, 25.8 trillion miles or 277,600 AU). Proxima centauri (one of alpha centauri's suns) is the closest star to ours.
Alpha Centuari is 4.4 light years away. We are talking about 44 trillion km (44,000,000,000,000 km) away. its actually is more like 42,479,700,000,000 kilometers away if you want it exact Alpha...