Pregnancy Calculator

Pregnancy Calculator

Local pregnancy calculators for planning and education—no network calls. Output is informational, not medical advice.

Capabilities

• Due date from LMP or conception: Uses 280 days from LMP (Naegele-style) or 266 days from conception; can infer LMP as conception minus 14 days. Returns gestational age at a reference date, trimester, days until due date, and milestone calendar dates (first/second trimester end, 24-week viability, 37-week full term, due date).
• Current week and development: From LMP and an optional reference date, returns completed weeks and days, trimester, percent progress against a 280-day calendar, a week-appropriate fetal development blurb, and a full embedded reference map of week-by-week summaries (weeks 4–42).
• Weight gain guidance: From pre-pregnancy weight, height, unit system (imperial or metric), and current whole weeks of gestation, computes pre-pregnancy BMI and IOM-style total gain ranges (underweight, normal, overweight, obese), plus expected cumulative gain by that week (first trimester about 1–4.4 lb total, then category-specific weekly rates in the 2nd/3rd trimesters).
• Baby size by week: For gestational weeks 4–42, returns illustrative length and weight with a common produce comparison, in inches/ounces or pounds and in centimeters/grams.
• Care and milestone timeline: From LMP, produces dated milestones for typical prenatal care, screening and ultrasound windows, trimester transitions, viability and full-term markers, and late/post-term planning notes (midpoints of common clinical windows).

Gotchas

• Not a substitute for care: All values are estimates; dating by ultrasound, cycle length, and clinical judgment can differ from LMP-based math.
• Weight guidance: IOM-style ranges are population guidance—individual targets may differ with multiples, medical conditions, or clinician recommendations.
• Size table: Illustrative averages only; ultrasound biometry is authoritative when available.
• Milestone dates: Real schedules vary by country, risk level, and provider—use the timeline as a planning sketch, not a checklist.