Mihintale is 12 kilometres east of Anuradhapura, the natural base. Tuk-tuks from Anuradhapura town centre run for around 1,500–2,000 LKR each way and can wait for you at the foot of the climb. Local buses (route 43) run hourly from Anuradhapura's New Bus Stand and drop you about ten minutes' walk from the entrance.
By car or hired van it is a 20-minute drive on the A12 toward Trincomalee. The whole site is easily seen as a half-day trip from Anuradhapura, leaving you the afternoon free for the ruins of the old capital.