Pregnancy weight gain calculator and week-by-week chart (kg)

How much weight should I gain in pregnancy?

It depends on your BMI before pregnancy. For one baby, the Institute of Medicine (2009) advises:

• 12.5 to 18 kg if you started under 18.5
• 11.5 to 16 kg from 18.5 to 24.9
• 7 to 11.5 kg from 25 to 29.9
• 5 to 9 kg at 30 or more

These use the standard BMI cut-offs, not the Asian ones.

Pregnancy weight gain by week, in kg

The week-by-week table Week 13 to 40, kg gained so far

Week	BMI under 18.5	BMI 18.5 to 24.9	BMI 25 to 29.9	BMI 30 or more
Week 13	0.5 to 2 kg	0.5 to 2 kg	0.5 to 2 kg	0.5 to 2 kg
Week 16	1.5 to 4 kg	1.5 to 3.5 kg	1 to 3 kg	1 to 3 kg
Week 20	3.5 to 6.5 kg	2.5 to 5.5 kg	2 to 4.5 kg	1.5 to 4 kg
Week 24	5 to 8.5 kg	4 to 7.5 kg	3 to 6 kg	2 to 5 kg
Week 28	7 to 11 kg	5.5 to 9.5 kg	3.5 to 7 kg	3 to 6.5 kg
Week 32	8.5 to 13.5 kg	7 to 11.5 kg	4.5 to 8.5 kg	3.5 to 7.5 kg
Week 36	10.5 to 15.5 kg	8.5 to 13.5 kg	5.5 to 10 kg	4 to 8.5 kg
Week 40	12.5 to 18 kg	11.5 to 16 kg	7 to 11.5 kg	5 to 9 kg

One baby, BMI before pregnancy. Everyone gains 0.5 to 2 kg by the end of week 13.

From week 14 the rows add the Institute of Medicine (2009) weekly gain for the second and third trimesters:

• 0.44 to 0.58 kg a week under 18.5
• 0.35 to 0.50 kg from 18.5 to 24.9
• 0.23 to 0.33 kg from 25 to 29.9
• 0.17 to 0.27 kg at 30 or more

Week 40 shows the Institute of Medicine total instead. Twins need their own plan.

How the rows were rounded

The total and the weekly rates are separate IOM figures, so the week 36 row does not lead exactly into week 40. Low ends are rounded down and high ends up to the half kg, so the table never narrows the IOM range.

Source: Institute of Medicine, Weight Gain During Pregnancy: Reexamining the Guidelines (2009).

How this works

It works out your BMI before pregnancy and uses the Institute of Medicine ranges (2009) for one baby: under 18.5, 12.5 to 18 kg; 18.5 to 24.9, 11.5 to 16 kg; 25 to 29.9, 7 to 11.5 kg; 30 or more, 5 to 9 kg. These ranges use the standard BMI cut-offs, not the Asian ones, because that's how the guidance was set. Twins and medical conditions change the numbers, so follow your doctor.

A number is a starting point, not a plan. On a free call, Puja looks at it with your reports and your routine.