An arrangement for an elevator, the elevator comprising at least an elevator car , a machine bed, a hoisting machine for moving the elevator car , at least one counter weight , and traction means that connect the elevator car and the at least one counter weight to each other, wherein the traction means pass through a traction sheave connected to the hoisting machine , and wherein a first mass (M 1 ) includes at least the mass of the elevator car and a second mass (M 2 ) includes at least the mass of the at least one counter weight , the arrangement further comprising: a first sensor for providing a first measuring result, the first measuring result representing a magnitude of a first force (F 1 ) which is affected by at least the first mass (M 1 ), a second sensor for providing a second measuring result, the second measuring result representing a magnitude of a second force (F 2 ) which aims to rotate the traction sheave to an opposite direction then the first force (F 1 ); and a computing unit for computing, on the basis of the first measuring result and the second measuring result, at least one of the following: - a difference between the first measuring result and the second measuring result, - a difference between the first force (F 1 ) and the second force (F 2 ), - a sum of the first measuring result and the second measuring result, - a sum of the first force (F 1 ) and the second force (F 2 ) characterized in that the machine bed comprises a first part and a second part ; the hoisting machine is mounted on the first part of the machine bed; and the first sensor and the second sensor are located between the first part and the second part of the machine bed. a first sensor for providing a first measuring result, the first measuring result representing a magnitude of a first force (F 1 ) which is affected by at least the first mass (M 1 ), a second sensor for providing a second measuring result, the second measuring result representing a magnitude of a second force (F 2 ) which aims to rotate the traction sheave to an opposite direction then the first force (F 1 ); and a computing unit for computing, on the basis of the first measuring result and the second measuring result, at least one of the following: - a difference between the first measuring result and the second measuring result, - a difference between the first force (F 1 ) and the second force (F 2 ), - a sum of the first measuring result and the second measuring result, - a sum of the first force (F 1 ) and the second force (F 2 ) characterized in that the machine bed comprises a first part and a second part ; the hoisting machine is mounted on the first part of the machine bed; and the first sensor and the second sensor are located between the first part and the second part of the machine bed. - a difference between the first measuring result and the second measuring result, - a difference between the first force (F 1 ) and the second force (F 2 ), - a sum of the first measuring result and the second measuring result, - a sum of the first force (F 1 ) and the second force (F 2 ) characterized in that the machine bed comprises a first part and a second part ; the hoisting machine is mounted on the first part of the machine bed; and the first sensor and the second sensor are located between the first part and the second part of the machine bed. <EOS>