Our animal pregnancy calculators cover dogs, cats, cows, horses, and rabbits. Click any card to load that calculator, or use the Animal Pregnancy tab above.
Our dog pregnancy calculator and dog pregnancy calculator week by week pictures mode calculates the expected whelping date from mating date. Dog gestation = 63 days from ovulation (58–68 day range). Enter breeding date for full timeline.
Our cat pregnancy calculator estimates the kittening date from the breeding date. Cat gestation is 63–65 days (9 weeks). Signs of pregnancy appear at 3–4 weeks. Enter mating date for the complete feline pregnancy timeline.
Our cow pregnancy calculator calculates the expected calving date from breeding or AI (artificial insemination) date. Bovine gestation averages 283 days (9.3 months). Dairy vs beef breeds may vary by 5–10 days.
Our free pregnancy calculator is more complete than WhatToExpect, AmericanPregnancy, and calculator.net — because it offers 5 specialized modes: LMP pregnancy calculator (standard OB/GYN method), IVF pregnancy calculator with 3-day and 5-day embryo transfer options, reverse calculation from due date, dog pregnancy calculator / cat pregnancy calculator / cow pregnancy calculator for animals, and a weight gain pregnancy calculator based on pre-pregnancy BMI. The pregnancy calculator week by week tracker shows fetal development for all 40 weeks — size comparisons, organ development milestones, and what to expect.
The standard pregnancy calculator due date uses Naegele's Rule: EDD = LMP + 280 days. This assumes a 28-day cycle and ovulation on day 14. For irregular cycles, the LMP pregnancy calculator adjusts: if your cycle is 32 days, ovulation occurs on day 18 (not 14), so 4 extra days are added to the EDD. The due date pregnancy calculator formula is used by every OB/GYN worldwide. Only ~5% of babies are born exactly on the EDD — most arrive between weeks 38–42.
LMP: January 15, 2025 · Cycle: 28 days
Ovulation: January 15 + 14 days = January 29, 2025
Due Date: January 15 + 280 days = October 22, 2025
If today is April 10, 2025:
Days since LMP: 85 days ÷ 7 = 12 weeks + 1 day pregnant
Currently in: 1st Trimester · Days remaining: 195
The IVF pregnancy calculator and pregnancy calculator IVF works differently because the embryo's exact age at transfer is known. For a Day 5 blastocyst transfer: EDD = Transfer Date + 261 days (because the embryo is already 5 days old, equivalent to 5 days past fertilization). For a Day 3 transfer: EDD = Transfer Date + 263 days. Our IVF pregnancy calculator also works for frozen embryo transfers (FET), egg donation, and gestational surrogacy — use the same formula based on embryo age at transfer.
Our pregnancy calculator week by week tracker shows what's happening at each stage. The week by week pregnancy calculator and week to week pregnancy calculator covers all 40 weeks:
| Weeks | Trimester | Baby Size | Key Milestone |
|---|---|---|---|
| 1–4 | 1st | Poppy seed | Implantation, hCG production begins |
| 5–8 | 1st | Raspberry | Heartbeat detectable at Week 6 |
| 9–12 | 1st | Lime | All organs formed, nuchal translucency scan |
| 13–16 | 2nd | Apple | Sex organs visible, movement begins |
| 17–20 | 2nd | Banana | Anatomy scan (20 weeks), gender possible |
| 21–27 | 2nd | Eggplant | Viability (~24 weeks), kicks felt regularly |
| 28–32 | 3rd | Coconut | 3rd trimester, rapid brain development |
| 33–36 | 3rd | Honeydew | Lungs maturing, baby drops (lightening) |
| 37–40 | 3rd | Watermelon | Full term at 39 weeks, ready to be born |
Our weight gain pregnancy calculator and weight gain during pregnancy calculator uses ACOG (American College of Obstetricians and Gynecologists) guidelines. First, it calculates your pre-pregnancy BMI, then applies the recommended gain range. Weight distribution in pregnancy: Baby (7–8 lbs), Placenta (1.5 lbs), Amniotic fluid (2 lbs), Breast tissue (2 lbs), Blood volume (4 lbs), Uterus (2 lbs), Fat stores (7 lbs) = Total ~25–35 lbs for normal BMI women.
Our dog pregnancy calculator week by week pictures guide: Week 1 (Days 1–7): Fertilization. Week 2 (Days 8–14): Embryos travel to uterus. Week 3 (Days 15–21): Implantation occurs. Week 4 (Days 22–28): Heartbeats detectable by ultrasound. Week 5 (Days 29–35): Fetuses develop rapidly. Week 6 (Days 36–42): Coat color and markings develop. Week 7 (Days 43–49): Fetuses fully formed. Week 8 (Days 50–56): Puppies ready to be born, nesting behavior. Week 9 (Days 57–63): Birth (whelping). Select "Dog Pregnancy" mode in the calculator above and enter your dog's mating date for the complete whelping date and week-by-week timeline.
Pregnancy calculator accuracy tip: The best way to confirm gestational age is a first-trimester ultrasound (7–13 weeks). Ultrasound dating is more accurate than LMP alone, especially if your cycles are irregular. If ultrasound measurements differ by more than 7 days from LMP-based EDD, your doctor may adjust your due date. Our pregnancy calculator how many weeks am I feature provides a starting estimate — always confirm with your healthcare provider.
Questions covering due date calculation, IVF pregnancy calculator, dog pregnancy calculator, week-by-week tracking, weight gain, and how many weeks pregnant.
The pregnancy calculator due date uses Naegele's Rule: EDD (Estimated Due Date) = First day of Last Menstrual Period (LMP) + 280 days (40 weeks). This assumes a regular 28-day cycle with ovulation on day 14. For a different cycle length, ovulation day adjusts: 24-day cycle = ovulation day 10, 32-day cycle = ovulation day 18. Our due date pregnancy calculator automatically adjusts for cycle length. An alternative formula: take LMP month, add 9 months, then add 7 days. Example: LMP March 15 → add 9 months = December 15 → add 7 days = December 22 EDD.
Our IVF pregnancy calculator and pregnancy calculator IVF mode works as follows: For a Day 5 blastocyst transfer: EDD = Transfer Date + 261 days. For a Day 3 embryo transfer: EDD = Transfer Date + 263 days. The logic is that IVF embryos have a known age, so we subtract their age from the standard 266 days (38 weeks from fertilization): Day 5 blastocyst = 266 − 5 = 261. Day 3 cleavage = 266 − 3 = 263. This makes the pregnancy calculator IVF much more precise than LMP-based methods. Our calculator also handles frozen embryo transfers (FET) — use the transfer date, same formula applies.
The pregnancy calculator how many weeks am I formula: Weeks pregnant = (Today − LMP) ÷ 7. Example: LMP was February 1, today is April 17 = 75 days apart ÷ 7 = 10 weeks + 5 days pregnant. Alternatively, use our "From Due Date" mode: enter your EDD and we calculate backward to tell you how many weeks pregnant you are today. Pregnancy is counted from LMP (not conception), so you are technically "2 weeks pregnant" at the moment of conception. Our pregnancy calculator week by week shows your exact week, trimester, and development stage.
Our dog pregnancy calculator estimates the whelping (birth) date from the mating date. Dog gestation = 63 days from ovulation (not from mating), with a range of 58–68 days from first mating. If your dog was mated on one day, add 63 days for the expected whelping date, but be prepared from day 58. Our dog pregnancy calculator week by week pictures shows: Week 1 (implantation), Week 3 (heartbeats), Week 4 (ultrasound confirms pregnancy), Week 6 (fetuses fully formed), Week 9 (birth). Select "Dog Pregnancy" mode and enter the mating date — works for our cat pregnancy calculator and cow pregnancy calculator too.
Our weight gain pregnancy calculator and weight gain during pregnancy calculator uses ACOG guidelines: Normal BMI (18.5–24.9): gain 25–35 lbs (11–16 kg) total. Underweight (BMI under 18.5): 28–40 lbs. Overweight (BMI 25–29.9): 15–25 lbs. Obese (BMI 30+): 11–20 lbs. Twins: add ~10–15 lbs to all ranges. Timing: First trimester: 1–5 lbs total. Second and third trimesters: approximately 1 lb/week for normal BMI. Use the Weight Gain tab in our calculator to get week-by-week targets based on your pre-pregnancy BMI and current pregnancy week.
The due date pregnancy calculator gender prediction timeline: NIPT blood test (Non-Invasive Prenatal Testing): Week 10–13 — most accurate (99%+). Ultrasound gender determination: Week 18–20 (anatomy scan) — reliable 80–95%. Ramzi theory (based on placenta location): Week 6–8 — scientifically unproven. Nub theory (genital tubercle angle): Week 12–13 — about 70% accurate when done by expert. Chinese gender prediction calendar — no scientific basis. Our pregnancy calculator shows the week-by-week timeline so you know exactly when to expect your anatomy scan and gender reveal possibility.