What do you tip a cab in Italy?

What is the customary amount to tip cab drivers in London, or Europe in general?

• I will be there in June and am trying to figure out a budget. I will only be using cabs for trips to and from the airports, so if I get a nice driver like I did last time, they will be loading and unloading my luggage. I always tip at least 20% at restaurants, unless the service is aweful, but I have no clue what to tip cab drivers. Is there a percentage?

• Answer:

  10% as the other posters responded. But might I suggest an alternative?? You may be in for a rather expensive fare from Heathrow or Gatwick airports to central London. Both airports are a minimum of 45 minutes to an hour drive, depending upon traffic, to central London. Best guess at fare from the airport to central London? 75-100 pounds (over $150 EACH WAY!) You may want to consider the "Heathrow Express" train direct to central London's Paddington St station or "Gatwick Express" to Victoria station. They each take about 15 minutes and cost about 15 pounds each way. Then, you can pick-up a taxi for the remainder of your journey to your hotel. Once in central London, the distances aren't that great, so the taxi fare would be reasonable. http://www.heathrowexpress.com (links to Gatwick Express too) Have a fabulous time!!