my baby is 3 months 16 days old 2 weeks back her weight was 5.1 when measured yesterday it was same is it normal?

A. Hello mom it would be better to measure the weight monthly as at times their could be variations,also preferably the same scale, monthly they are expected to gain about 300 gm to 1kg and by the age of 4 to 6 months they would almost double their birth weight