Two different things get called "a taxi to Pattaya" and the price gap between them is the whole story.
A street taxi or Grab from the airport runs roughly 1,200-1,700 THB. You negotiate, or you watch the meter plus motorway tolls, and you take whatever car turns up. It is the cheapest door-to-door option and it is fine if you land in daylight, speak enough Thai or English to hold your ground, and are not travelling with three suitcases and a tired child.
A pre-booked private transfer costs more and buys certainty: a named driver waiting in arrivals with your flight number, a fixed price agreed before you fly, and a vehicle sized to your actual luggage. Checked on Kiwitaxi in September 2026, the Suvarnabhumi to Pattaya ladder runs about 1,917 THB for a comfort sedan (4 passengers, 3 bags), 2,126 THB for a minivan (4 passengers, 4 bags), 2,684 THB for a 7-seat minibus and 2,962 THB for 10 seats.
Do the per-person arithmetic before you decide. Two people in a sedan is around 960 THB each against 130 THB on the bus, which is hard to justify unless you are exhausted. Seven people in a minibus is about 383 THB each, and now you are comparing a door-to-door car against seven bus tickets, a terminal transfer at the Pattaya end and the logistics of moving seven people with bags. The bus is always cheaper. The transfer stops being extravagant somewhere around four passengers, a late-night landing, or a Don Mueang arrival that has missed the last direct bus.