Modular measuring device for determining a density of a measuring medium, comprising: a carrier module, a first measuring tube module and at least one further measuring tube module (40, 60), wherein the carrier module has a receptacle for detachably fastening the first measuring tube module or the at least one further measuring tube module (40, 60), a contactless temperature sensor for determining an oscillating tube temperature, a primary exciter component and a primary sensor component, wherein each measuring tube module (20, 40, 60) comprises a fixation (21, 41, 61) complementary to the receptacle of the carrier module, a vibration tube (22, 42, 62), a secondary exciter component (23, 43, 63) complementary to the primary exciter component and a secondary sensor component (24, 44, 64) complementary to the primary sensor component, wherein each oscillating tube (22, 42, 62) of the measuring tube modules (20, 40, 60) has a different tube diameter (RD1, RD2, RD3), a straight first tube leg (25, 45, 65), a straight second tube leg (26, 46, 66), a curved first tube bend (27, 47, 67) and a curved second tube bend (28, 48, 68) wherein the first pipe legs (25, 45, 65) are each connected to the first pipe bends (27, 47, 67) at a primary connection point (VP1, VP2, VP3), the first pipe bends (27, 47, 67) are connected to the second pipe bends (28, 48, 68), and the second pipe bends (28, 48, 68) are each connected to the first pipe legs (26, 46, 66) at a secondary connection point (VS1, VS2, VS3), whereby the primary connection point (VP1, VP2, VP3) and the secondary connection point (VS1, VS2, VS3) for each measuring tube module (20, 40, 60) lie in a respective plane (E1, E2, E3), wherein the planes (E1, E2, E3) have a respective distance (A1, A2, A3) from one another, which corresponds to a difference (D1, D2, D3) between the respective pipe diameters (RD1, RD2, RD3), wherein the first pipe bends (27, 47, 67) and the second pipe bends (28, 48, 68) have an identical inner radius (IR1, IR2, IR3) or an identical outer radius (AR1, AR2, AR3), so that the center lines (ML1, ML2, ML3) associated with the respective oscillating tubes (22, 42, 62) intersect at a first intersection point and at a second intersection point, wherein the contactless temperature sensor is arranged such that when a measuring tube module (20, 40, 60) is accommodated in the carrier module, the contactless temperature sensor is directed towards the first intersection point or the second intersection point. wherein the carrier module has a receptacle for detachably fastening the first measuring tube module or the at least one further measuring tube module (40, 60), a contactless temperature sensor for determining an oscillating tube temperature, a primary exciter component and a primary sensor component, wherein each measuring tube module (20, 40, 60) comprises a fixation (21, 41, 61) complementary to the receptacle of the carrier module, a vibration tube (22, 42, 62), a secondary exciter component (23, 43, 63) complementary to the primary exciter component and a secondary sensor component (24, 44, 64) complementary to the primary sensor component, wherein each oscillating tube (22, 42, 62) of the measuring tube modules (20, 40, 60) has a different tube diameter (RD1, RD2, RD3), a straight first tube leg (25, 45, 65), a straight second tube leg (26, 46, 66), a curved first tube bend (27, 47, 67) and a curved second tube bend (28, 48, 68) wherein the first pipe legs (25, 45, 65) are each connected to the first pipe bends (27, 47, 67) at a primary connection point (VP1, VP2, VP3), the first pipe bends (27, 47, 67) are connected to the second pipe bends (28, 48, 68), and the second pipe bends (28, 48, 68) are each connected to the first pipe legs (26, 46, 66) at a secondary connection point (VS1, VS2, VS3), whereby the primary connection point (VP1, VP2, VP3) and the secondary connection point (VS1, VS2, VS3) for each measuring tube module (20, 40, 60) lie in a respective plane (E1, E2, E3), wherein the planes (E1, E2, E3) have a respective distance (A1, A2, A3) from one another, which corresponds to a difference (D1, D2, D3) between the respective pipe diameters (RD1, RD2, RD3), wherein the first pipe bends (27, 47, 67) and the second pipe bends (28, 48, 68) have an identical inner radius (IR1, IR2, IR3) or an identical outer radius (AR1, AR2, AR3), so that the center lines (ML1, ML2, ML3) associated with the respective oscillating tubes (22, 42, 62) intersect at a first intersection point and at a second intersection point, wherein the contactless temperature sensor is arranged such that when a measuring tube module (20, 40, 60) is accommodated in the carrier module, the contactless temperature sensor is directed towards the first intersection point or the second intersection point.