How much weight should I gain during pregnancy?

It depends on your BMI before pregnancy: 25 to 35 lb (11.5 to 16 kg) for a normal BMI, less if you started overweight, more if underweight.

How much weight do you gain with twins?

37 to 54 lb for a normal pre-pregnancy BMI, 31 to 50 lb if overweight and 25 to 42 lb with obesity.

Are these calculators free?

Yes. Every calculator is free with no sign-up. Clearly labeled ads keep it that way.

Calculations run in your browser. Share links put inputs in the URL, which can be read by anyone you send it to and is sent to the hosting server when opened. Avoid sharing sensitive numbers. Currency conversion requests public exchange rates.

How accurate are the results?

Results follow the formulas and assumptions shown, with normal rounding and numerical limits. Taxes, rates and health guidance can change, so treat these as estimates and confirm important decisions with a qualified professional.

Pregnancy Weight Gain Calculator

Recommended pregnancy weight gain for your BMI, week by week.

100% Free
Instant Results
No Sign Up

Pregnancy Weight Gain Calculator

Healthy pregnancy weight gain by week (IOM)

Units

Height

Weight before pregnancy

Weeks pregnant

weeks

Expecting twins

Recommended gain by week 20

7.3 - 12.3 lb

Weight 147.3 - 152.3 lb at week 20

Pre-pregnancy BMI: 23.3 (Normal weight)
Total gain by 40 weeks: 25 - 35 lb
First trimester total: 1.1 - 4.4 lb
Weekly gain after week 13: 0.89 - 1.13 lb

Based on the Institute of Medicine (now National Academy of Medicine) 2009 guidelines, endorsed by ACOG. Week-by-week values assume steady gain after the first trimester. Not medical advice; your provider may suggest a different target.

Recommended weight (lb)

Low
High

BMI	Category	Single baby	Twins
under 18.5	Underweight	28 - 40 lb	No guideline
18.5 - 24.9	Normal weight	25 - 35 lb	37 - 54 lb
25 - 29.9	Overweight	15 - 25 lb	31 - 50 lb
30 and over	Obese	11 - 20 lb	25 - 42 lb

Week	Gain	Weight
Week 1	0.1 - 0.3 lb	140.1 - 140.3 lb
Week 2	0.2 - 0.7 lb	140.2 - 140.7 lb
Week 3	0.3 - 1 lb	140.3 - 141 lb
Week 4	0.3 - 1.4 lb	140.3 - 141.4 lb
Week 5	0.4 - 1.7 lb	140.4 - 141.7 lb
Week 6	0.5 - 2 lb	140.5 - 142 lb
Week 7	0.6 - 2.4 lb	140.6 - 142.4 lb
Week 8	0.7 - 2.7 lb	140.7 - 142.7 lb
Week 9	0.8 - 3 lb	140.8 - 143 lb
Week 10	0.8 - 3.4 lb	140.8 - 143.4 lb
Week 11	0.9 - 3.7 lb	140.9 - 143.7 lb
Week 12	1 - 4.1 lb	141 - 144.1 lb
Week 13	1.1 - 4.4 lb	141.1 - 144.4 lb
Week 14	2 - 5.5 lb	142 - 145.5 lb
Week 15	2.9 - 6.7 lb	142.9 - 146.7 lb
Week 16	3.8 - 7.8 lb	143.8 - 147.8 lb
Week 17	4.6 - 8.9 lb	144.6 - 148.9 lb
Week 18	5.5 - 10.1 lb	145.5 - 150.1 lb
Week 19	6.4 - 11.2 lb	146.4 - 151.2 lb
Week 20	7.3 - 12.3 lb	147.3 - 152.3 lb
Week 21	8.2 - 13.5 lb	148.2 - 153.5 lb
Week 22	9.1 - 14.6 lb	149.1 - 154.6 lb
Week 23	10 - 15.7 lb	150 - 155.7 lb
Week 24	10.8 - 16.9 lb	150.8 - 156.9 lb
Week 25	11.7 - 18 lb	151.7 - 158 lb
Week 26	12.6 - 19.1 lb	152.6 - 159.1 lb
Week 27	13.5 - 20.3 lb	153.5 - 160.3 lb
Week 28	14.4 - 21.4 lb	154.4 - 161.4 lb
Week 29	15.3 - 22.5 lb	155.3 - 162.5 lb
Week 30	16.1 - 23.7 lb	156.1 - 163.7 lb
Week 31	17 - 24.8 lb	157 - 164.8 lb
Week 32	17.9 - 25.9 lb	157.9 - 165.9 lb
Week 33	18.8 - 27.1 lb	158.8 - 167.1 lb
Week 34	19.7 - 28.2 lb	159.7 - 168.2 lb
Week 35	20.6 - 29.3 lb	160.6 - 169.3 lb
Week 36	21.5 - 30.5 lb	161.5 - 170.5 lb
Week 37	22.3 - 31.6 lb	162.3 - 171.6 lb
Week 38	23.2 - 32.7 lb	163.2 - 172.7 lb
Week 39	24.1 - 33.9 lb	164.1 - 173.9 lb
Week 40	25 - 35 lb	165 - 175 lb

More Fitness & Health Calculators

View all calculators

Every calculator you need.

Free, fast, and easy to use.

Browse all 204 calculators

Calculators: 204+
Free to use: 100%
Results as you type: Instant

How the pregnancy weight gain calculator works

The Institute of Medicine's 2009 guidelines set total pregnancy weight gain by pre-pregnancy BMI: 28 to 40 lb if underweight, 25 to 35 lb at a normal weight, 15 to 25 lb if overweight and 11 to 20 lb with obesity. For twins the provisional ranges are 37 to 54, 31 to 50 and 25 to 42 lb.

Most women gain 1.1 to 4.4 lb (0.5 to 2 kg) in the first trimester, then gain at a fairly steady weekly rate. The chart and table spread the remaining gain evenly over weeks 14 to 40.

Using and checking your result

Published by JustYourCalculator. Check the units and assumptions above, and compare a known example before relying on the output. Calculations use browser arithmetic and may round displayed values.

This tool provides an estimate, not a diagnosis, treatment plan or individualized medical advice. Population formulas may not fit children, pregnancy, athletes or people with health conditions. Discuss health decisions with a qualified clinician.

Share links may contain your input values. Anyone with the URL can read them; avoid sharing sensitive personal or financial information.