Pregnancy Weight Gain Calculator

Understand pregnancy weight gain by BMI

Why weight gain guidance matters

Healthy, steady weight gain supports fetal growth, reduces complications, and helps you feel energetic. Recommendations depend on your prepregnancy BMI and whether you’re carrying one baby or twins. Use these numbers as educational guideposts, not strict rules.

How BMI categories affect targets

• Underweight (BMI < 18.5): Total 12.5–18 kg (28–40 lb).
• Normal (18.5–24.9): Total 11.5–16 kg (25–35 lb).
• Overweight (25–29.9): Total 7–11.5 kg (15–25 lb).
• Obesity (≥ 30): Total 5–9 kg (11–20 lb).

Weekly gain during the 2nd–3rd trimesters typically ranges from about 0.22–0.50 kg (0.5–1.1 lb) depending on BMI, with a smaller total in the 1st trimester (often 0.5–2 kg or 1–5 lb).

Weekly rate and trimester distribution

Most gain occurs after week 13. Our calculator assigns a small allowance to the 1st trimester, then distributes the remainder evenly across weeks 14–40 to estimate a weekly rate and show a trimester doughnut chart for quick understanding.

Twin pregnancy considerations

Twin pregnancies usually have higher total targets and slightly higher weekly rates. Always follow your clinician’s individualized guidance, especially for twins or medical conditions.

Practical tips for healthy gain

• Choose nutrient-dense foods: Prioritize proteins, whole grains, fruits, vegetables, and healthy fats.
• Hydrate consistently: Adequate fluids support blood volume and amniotic fluid.
• Move regularly: Light-to-moderate activity if cleared by your clinician supports energy and comfort.
• Track gently: Weigh under similar conditions weekly; monitor the overall trend rather than day-to-day fluctuations.

Important disclaimer

This calculator offers educational estimates for global use and does not replace personalized advice. If you have concerns about symptoms or weight changes, consult a qualified healthcare professional.

Frequently asked questions

• HOW TO calculate my pregnancy BMI? Convert weight and height to the same system (kg/cm or lb/in), then BMI = weight (kg) ÷ [height (m)]². Our tool computes this automatically when you enter your details.
• HOW TO know my recommended total gain? Your BMI category and pregnancy type set a range. The tool displays it in kg and lb and breaks it down by trimester.
• HOW TO find my weekly weight gain target? After week 13, divide the remaining recommended gain by the weeks left. The tool calculates a per‑week estimate for you.
• HOW TO check if I’m on track? Enter your current weight. We compare your change since conception to a recommended range for your current week and show “Below”, “On track”, or “Above”.
• HOW TO handle twins? Select “Twins” to see higher recommended ranges and weekly rates appropriate for multifetal pregnancies.
• HOW TO switch units? Choose Metric (kg, cm) or Imperial (lb, ft/in). Values and results update automatically.