Weighing scales (or
weigh scales or
scales) are devices to
measure weight or calculate
mass.
Spring balances or
spring scales measure weight (force) by balancing the force due to gravity against the force on a spring, whereas a balance or pair of scales using a balance beam compares masses by balancing the weight due to the mass of an object against the weight of a known mass or masses. Either type can be calibrated to read in units of force such as
newtons, or in units of mass such as
kilograms, but the balance or pair of scales using a traditional balance beam to compare masses will read correctly for mass even if moved to a place with a different (non-zero) gravitational field strength (but would then not read correctly if calibrated in units of force), while the spring balance would read correctly in
force in a different gravitational field strength (but would not read correctly if calibrated in units of mass).