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.