Solverly

Pregnancy Weight Gain Calculator

This tool estimates a healthy, week-by-week weight-gain trajectory using your starting BMI and current gestational week. It shows where you are relative to typical trimester targets and a recommended total range, which is helpful for setting expectations, planning meals, and having clearer conversations during prenatal visits.

The Pregnancy Weight Gain Calculator helps us translate guidelines into practical goals—steady progress, a sensible pace, and an easy snapshot of how today’s trend lines up with the end-of-pregnancy target. The aim is to support confident choices throughout each trimester so you can track progress, anticipate adjustments, and focus on what matters most for you and baby.

View weekly and total recommended pregnancy weight gain ranges by BMI, with a clear timeline and weekly pace.

Enter your details (education-only)

Quick breakdown

BMI (pre-pregnancy)
25.02
Category
Overweight
Weekly pace (2nd/3rd tri)
0.5–0.7 lb/wk
Cumulative expected (now)
4.5–9.4 lb
Gained so far
13 lb
Forward pace to midpoint
0.35 lb/wk

Educational estimate. Follow guidance from your healthcare team for individualized targets.

Results interpretation

We map pre-pregnancy BMI to a recommended total range and a typical weekly pace during the second and third trimesters. The cumulative line shows where we are now, recognizing that early gain is usually small and later weeks add at a steady pace.

  • Cumulative expected: the range for the current week.
  • Weekly pace: a typical per-week gain in the second and third trimesters.
  • Forward pace: the average weekly amount to reach the midpoint of the recommended total by week 40.

How it works

We compute BMI from pre-pregnancy measurements, choose a recommendation band, and project a week-by-week cumulative range using a small first-trimester total and a per-week pace thereafter.

Formulas, steps, assumptions, limitations

BMI: BMI = weight(kg) ÷ height(m)2. Conversions: 1 lb = 0.45359237 kg; 1 in = 0.0254 m; 1 cm = 0.01 m.

First trimester total: ~1–4.5 lb (≈ 0.5–2 kg) distributed linearly to week 13.

Weekly pace (2nd/3rd tri): category-specific low–high band applied from week 14 onward.

Cumulative expected at week w ≤ 13: range = (w/13) × T1low..high.

Cumulative expected at week w > 13: T1 + (w−13) × pacelow..high.

Limitations: singleton focus; ranges are estimates; individual care varies with health history and clinical judgment.

Use cases & examples

Mid-pregnancy check

Week 22, BMI in “Normal.” Cumulative range ≈ 9–14 lb. Gained 11 lb → within range. Forward pace ≈ 0.7 lb/wk to midpoint.

Early weeks

Week 8. Expected cumulative is small. Minor fluctuations from time of day or meals are common—trend matters more than a single reading.

Tight timeline

Week 34, gained below range. Forward pace shows the average per week to reach the midpoint; follow clinical advice for any adjustments.

Pregnancy weight gain FAQs

Why is early gain small?

First-trimester totals are modest; most gain occurs later as the pregnancy progresses.

Do we track daily?

Weekly or biweekly is plenty. Use similar timing and clothing to reduce noise.

What if BMI is near a boundary?

Categories are guides, not sharp lines. Discuss individual targets with your clinician.

Can we use kilograms and centimeters?

Yes—pick your units in the inputs. We convert internally and display results in your chosen unit.

Does activity level change targets?

Targets are primarily BMI-based. Nutrition and activity influence the path; your care team can tailor advice.

Is water retention a factor?

Yes. Hydration and timing can shift scale readings. Look for trends rather than single-day changes.

Understanding Pregnancy Weight Gain: A Week-by-Week Planning Guide

We use week-by-week ranges to make a complex topic practical. The ranges connect three ideas: where we started (pre-pregnancy BMI), how far along we are (gestational week), and how gain typically distributes across trimesters. Our goal is a calm, useful picture rather than perfect predictions.

Why ranges, not exact targets?

Bodies don’t follow straight lines. Sleep, stress, meals, hydration, and time of day can shift weights by a pound or two. A range absorbs those shifts while still keeping us oriented.

A simple mental model

Early weeks are gentle; later weeks add steadily. That’s why our cumulative line starts near zero and then climbs at a category-specific pace. If a reading is outside the band on a given day, we look for confirmation over the next week instead of reacting to a single data point.

Consistency beats precision

We weigh in around the same time of day, on the same scale, and with similar clothing. If the number seems off, we recheck in 24–48 hours. Trends tell the real story.

Nutrition and movement support

Balanced meals, simple snacks, and regular movement help many households feel better during pregnancy. Small habits—like keeping water handy, pairing fruit with yogurt or nuts, and short post-meal walks—often make the process more comfortable while supporting steady progress.

Putting the timeline to work

The forward-pace line estimates how much per week would reach the midpoint of the recommended total by 40 weeks. It’s a planning aid, not a prescription. Your healthcare team can tailor targets to your needs.

Context matters

Medical history, symptoms, and lab results all matter. Our calculator is designed to complement—not replace— clinical guidance. When questions come up, we bring our notes and numbers to the next appointment.