It's a bit of both. The size of the tattoo generally determines how long it will take! The hourly rate generally applies to larger pieces. For smaller tattoos, especially if they take less than an hour, the price is determined more by the size/location/level of detail, etc. Also, to make a slight correction to Kaitlin's reply- If the tattoo takes under an hour, it will be anywhere between $100-$200.
According to the site, it depends, but my tattoos have always been priced by time. The only exception was one that took under an hour, and for that they charge the shop minimum of $100.
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