The options of getting to Porto from the airport include: taxi, metro, bus.
Taxi. It’s the simplest and most efficient method of transferring into the city. Most taxis are beige, but they can also be black with a green roof. They are modern and comfortable and are readily available from the stand at the airport. The green light on top indicates that the cab is free, and many drivers are competent English speakers. The fare is metered, but should come to around 23 EUR in normal fare conditions. The rates are also higher at night-time as well as Holy Days, public holidays and weekends, so expect to pay around 20% more if your journey falls within any of these times.
Metro. The Metro of Porto provides a quick transit into the city from the airport and is the most popular method of public transport available. The train takes approximately 30 minutes to reach the centre city, leaving every 20 - 30 minutes (even on weekends and holidays) and stops at many convenient locations along the way. The fee is based on zones. The transit from the airport will cost 2.45 EUR to the city centre, which includes a refundable card fee of 0.60 EUR.
Bus. Bus lines run from the airport to various points within the city. Buses are run by companies STCP or Resende and have different routes, destinations, and timings. Most buses will run at 30 minute intervals, starting at around 6 am, the latest ending at midnight. The buses that go into the city are 601, 602 and 604 as well as the 119 and 3M and 105N in the evenings. Dependent on which bus you take and on which route the price will be slightly different. However, a journey into the city shouldn't cost you more than 2.40 EUR, plus the 0.60 EUR for the rechargeable card. This method isn’t the most convenient as multiple bus lines and times can be confusing to understand.