A thermal inkjet printhead with heater elements disposed in respective bubble forming chambers for heating part of the ejectable liquid above its boiling point to form a gas bubble that causes the ejection of a drop of the ejectable liquid from the nozzle, wherein, the heater is separated from the nozzle by less than 5 .mu.m at their closest points; the nozzle length is less than 5 .mu.m; and the ejectable liquid has a viscosity less than 5 cP. The volume of liquid between the heater and the nozzle determines the inertia of the liquid and its acceleration in response to bubble formation. Moving the heater closer to the nozzle reduces the inertia of the liquid and increases its acceleration, so a lower bubble impulse is needed to eject a drop. This allows the printhead to use smaller heater elements with lower power requirements. Viscous drag in the nozzle reduces the momentum of fluid flowing through the nozzle. The viscous drag increases as the nozzle length (in the direction of fluid flow) increases. By reducing the nozzle length, a lower bubble impulse is needed to eject a drop. This also allows the printhead to use smaller heater elements with lower power requirements.