Pregnancy Weight Gain Calculator

Week	Recommended weight	Recommended gain
Week 1	120.0 – 120.0 lb	0 – 0 lb
Week 2	120.1 – 120.4 lb	0.09 – 0.4 lb
Week 3	120.2 – 120.7 lb	0.2 – 0.7 lb
Week 4	120.3 – 121.1 lb	0.3 – 1.1 lb
Week 5	120.4 – 121.5 lb	0.4 – 1.5 lb
Week 6	120.5 – 121.8 lb	0.5 – 1.8 lb
Week 7	120.5 – 122.2 lb	0.6 – 2.2 lb
Week 8	120.6 – 122.6 lb	0.6 – 2.6 lb
Week 9	120.7 – 122.9 lb	0.7 – 2.9 lb
Week 10	120.8 – 123.3 lb	0.8 – 3.3 lb
Week 11	120.9 – 123.7 lb	0.9 – 3.7 lb
Week 12	121.0 – 124.0 lb	1.0 – 4.0 lb
Week 13	121.1 – 124.4 lb	1.1 – 4.4 lb
Week 14	122.0 – 125.5 lb	2.0 – 5.5 lb
Week 15	122.9 – 126.7 lb	2.9 – 6.7 lb
Week 16	123.8 – 127.8 lb	3.8 – 7.8 lb
Week 17	124.6 – 128.9 lb	4.6 – 8.9 lb
Week 18	125.5 – 130.1 lb	5.5 – 10.1 lb
Week 19	126.4 – 131.2 lb	6.4 – 11.2 lb
Week 20	127.3 – 132.3 lb	7.3 – 12.3 lb
Week 21	128.2 – 133.5 lb	8.2 – 13.5 lb
Week 22	129.1 – 134.6 lb	9.1 – 14.6 lb
Week 23	130.0 – 135.7 lb	10.0 – 15.7 lb
Week 24	130.8 – 136.9 lb	10.8 – 16.9 lb
Week 25	131.7 – 138.0 lb	11.7 – 18.0 lb
Week 26	132.6 – 139.1 lb	12.6 – 19.1 lb
Week 27	133.5 – 140.3 lb	13.5 – 20.3 lb
Week 28	134.4 – 141.4 lb	14.4 – 21.4 lb
Week 29	135.3 – 142.5 lb	15.3 – 22.5 lb
Week 30	136.1 – 143.7 lb	16.1 – 23.7 lb
Week 31	137.0 – 144.8 lb	17.0 – 24.8 lb
Week 32	137.9 – 145.9 lb	17.9 – 25.9 lb
Week 33	138.8 – 147.1 lb	18.8 – 27.1 lb
Week 34	139.7 – 148.2 lb	19.7 – 28.2 lb
Week 35	140.6 – 149.3 lb	20.6 – 29.3 lb
Week 36	141.5 – 150.5 lb	21.5 – 30.5 lb
Week 37	142.3 – 151.6 lb	22.3 – 31.6 lb
Week 38	143.2 – 152.7 lb	23.2 – 32.7 lb
Week 39	144.1 – 153.9 lb	24.1 – 33.9 lb
Week 40	145.0 – 155.0 lb	25.0 – 35.0 lb

Week

Recommended weight

Recommended gain

Week 1

120.0 – 120.0 lb

0 – 0 lb

Week 2

120.1 – 120.4 lb

0.09 – 0.4 lb

Week 3

120.2 – 120.7 lb

0.2 – 0.7 lb

Week 4

120.3 – 121.1 lb

0.3 – 1.1 lb

Week 5

120.4 – 121.5 lb

0.4 – 1.5 lb

Week 6

120.5 – 121.8 lb

0.5 – 1.8 lb

Week 7

120.5 – 122.2 lb

0.6 – 2.2 lb

Week 8

120.6 – 122.6 lb

0.6 – 2.6 lb

Week 9

120.7 – 122.9 lb

0.7 – 2.9 lb

Week 10

120.8 – 123.3 lb

0.8 – 3.3 lb

Week 11

120.9 – 123.7 lb

0.9 – 3.7 lb

Week 12

121.0 – 124.0 lb

1.0 – 4.0 lb

Week 13

121.1 – 124.4 lb

1.1 – 4.4 lb

Week 14

122.0 – 125.5 lb

2.0 – 5.5 lb

Week 15

122.9 – 126.7 lb

2.9 – 6.7 lb

Week 16

123.8 – 127.8 lb

3.8 – 7.8 lb

Week 17

124.6 – 128.9 lb

4.6 – 8.9 lb

Week 18

125.5 – 130.1 lb

5.5 – 10.1 lb

Week 19

126.4 – 131.2 lb

6.4 – 11.2 lb

Week 20

127.3 – 132.3 lb

7.3 – 12.3 lb

Week 21

128.2 – 133.5 lb

8.2 – 13.5 lb

Week 22

129.1 – 134.6 lb

9.1 – 14.6 lb

Week 23

130.0 – 135.7 lb

10.0 – 15.7 lb

Week 24

130.8 – 136.9 lb

10.8 – 16.9 lb

Week 25

131.7 – 138.0 lb

11.7 – 18.0 lb

Week 26

132.6 – 139.1 lb

12.6 – 19.1 lb

Week 27

133.5 – 140.3 lb

13.5 – 20.3 lb

Week 28

134.4 – 141.4 lb

14.4 – 21.4 lb

Week 29

135.3 – 142.5 lb

15.3 – 22.5 lb

Week 30

136.1 – 143.7 lb

16.1 – 23.7 lb

Week 31

137.0 – 144.8 lb

17.0 – 24.8 lb

Week 32

137.9 – 145.9 lb

17.9 – 25.9 lb

Week 33

138.8 – 147.1 lb

18.8 – 27.1 lb

Week 34

139.7 – 148.2 lb

19.7 – 28.2 lb

Week 35

140.6 – 149.3 lb

20.6 – 29.3 lb

Week 36

141.5 – 150.5 lb

21.5 – 30.5 lb

Week 37

142.3 – 151.6 lb

22.3 – 31.6 lb

Week 38

143.2 – 152.7 lb

23.2 – 32.7 lb

Week 39

144.1 – 153.9 lb

24.1 – 33.9 lb

Week 40

145.0 – 155.0 lb

25.0 – 35.0 lb

Enter pregnancy week, height, pre-pregnancy weight, and current weight to see a transparent planning range for this week and the published total range at week 40. The calculator supports singleton and twin pregnancies in US or metric units.

Total gain ranges used

Pre-pregnancy BMI	Category	One baby	Twins
Below 18.5	Underweight	28–40 lb	50–62 lb*
18.5–24.9	Healthy weight	25–35 lb	37–54 lb
25.0–29.9	Overweight	15–25 lb	31–50 lb
30.0 and above	Obesity	11–20 lb	25–42 lb

* CDC states that the underweight-twin recommendation is the exception in its table that is not from the Institute of Medicine. Triplets and higher-order pregnancies are outside this calculator's scope.

For singleton pregnancies, the 2009 IOM report also publishes approximate second- and third-trimester weekly rates by BMI. This calculator uses the total range as its week-40 endpoint, so its straight-line weekly band should not be confused with those separate rate ranges.

Examples

5 ft 6 in, 120 lb before, 130 lb at week 20

Pre-pregnancy BMI is 19.4 (Normal Weight). The interpolated week-20 band is 127.3–132.3 lb, so 130 lb falls inside it. The published week-40 total of 25–35 lb corresponds to 145.0–155.0 lb.

Underweight twin pregnancy: 5 ft 6 in and 100 lb before

The published total used is 50–62 lb, making the week-40 range 150.0–162.0 lb. At week 20, the calculator's interpolation is 113.8–119.3 lb. Those weekly numbers are planning points rather than a separate CDC recommendation.

165 cm, 50 kg before, 55 kg at week 20

BMI is 18.4 (Underweight). For one baby, the interpolated week-20 range is 53.7–56.2 kg, and the published week-40 total corresponds to 62.7–68.1 kg.

Formula

Pre-pregnancy BMI selects the applicable published total-gain range. The weekly values are CalculatorBuddy's piecewise-linear planning interpolation:

BMI = weight (kg) / height (m)²

week 1:   gain = 0
week 13:  gain = 1.1–4.4 lb (0.5–2 kg)
week 40:  gain = published total for the BMI and pregnancy type
other weeks: straight-line interpolation between those points

planning weight = pre-pregnancy weight + interpolated gain

The weekly curve is a planning aid, not a clinical target or diagnostic threshold. Published guidance emphasizes an individualized goal and monitoring the pattern over time with prenatal care.

Sources

Frequently asked questions

How much weight is recommended during pregnancy?

Published total ranges depend on pre-pregnancy BMI and the number of babies. For one baby, the ranges are 28–40 lb if underweight, 25–35 lb at a healthy BMI, 15–25 lb if overweight, and 11–20 lb at BMI 30 or higher. These are population ranges, so a prenatal care provider may set a different goal for an individual pregnancy.

Is the weekly range an official clinical cutoff?

No. The calculator draws a straight planning line from zero gain at week 1 to 1.1–4.4 lb at week 13 and then to the published total at week 40. The total ranges and first-trimester assumption are sourced; each weekly point is CalculatorBuddy's interpolation and should not be treated as a diagnostic threshold.

What ranges are used for twins?

The totals are 50–62 lb for an underweight pre-pregnancy BMI, 37–54 lb for a healthy BMI, 31–50 lb if overweight, and 25–42 lb at BMI 30 or higher. CDC notes that the 50–62 lb underweight-twin range is the one exception in its table that does not come from IOM.

What if my weight is outside this week's planning band?

One reading above or below an interpolated band is not a diagnosis. Measurement differences, nausea, hydration, swelling, and individual circumstances can affect the trend. Discuss persistent or sudden changes with a prenatal care provider.

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