My child is 3yrs old and wt is near to 12kg.and her ht is 92cm.is this ideal weight and height for a girl?

Proportioned weight: Ideal weight really depends on genetics and activity level (muscle weighs more than fat!) but a quick way to estimate a proportional weight for a height of 92 cm is to use a growth chart such as the one pictured. Height for age plots in the 50th (average percentile), and a proportional weight would be approximately 13kg. General growth trends over time and BMI calculation may be more useful.

See Image attached.: Your child is right along the 10th % line for curve for both. So the height and weight match up. But what that means is your daughter is taller and heavier than 1 out of 10 girls her age. Every child grows at different rates. Other factors to consider are her parents heights and growth curves as well.