Tourism is a major economic contributor to the Kingdom of Thailand. Estimates of tourism revenue directly contributing to the Thai GDP of 12 trillion baht range from one trillion baht (2013) 2.53 trillion baht (2016), the equivalent of 9 per cent to 17.7 per cent of GDP. When including indirect travel and tourism receipts, the 2014 total is estimated to be the equivalent of 19.3 percent (2.3 trillion baht) of Thailand's GDP:1 The actual contribution of tourism to GDP is lower than these percentages because GDP is measured in value added not revenue. The valued added of the Thailand's tourism industry is not known (value added is revenue less purchases of inputs).