Due Date Calculator

Supports LMP, ovulation day and IVF transfer date, auto-corrects cycle length, shows daily fetal size & fruit comparison, prenatal visit reminders and labour countdown—never miss a key milestone.

Calculate Now Features

Accurate Due Date Calculation

Choose the method that suits you best and get the most accurate EDD

Select the first day of bleeding
Default 28; enter your average if irregular
Via OPK, BBT or ultrasound
Most women 14 days; keep default if unsure
Select actual transfer date (not egg-retrieval)
Different ages → different GA calculation
For personalised visit advice (optional)
Affects check-up frequency
Multiples have a different full-term standard

Prenatal Check-up Schedule

Detailed time-table by trimester

GA weekVisitTests & Ultrasound
7-8 w1ˢᵗRoutine, TSH, TORCH, CBC, UA, vaginal swab, LFT/RFT, lipids, glucose, coagulation, early scan, etc.
11-14 w2ⁿᵈRoutine, NT scan
15-19 w3ʳᵈRoutine, level-II scan
GA weekVisitTests & Ultrasound
20-24 w4ᵗʰRoutine, anatomy scan + fetal echo
25-28 w5ᵗʰRoutine, OGTT, CBC, ferritin, UA
29-30 w6ᵗʰRoutine, maternal echo
GA weekVisitTests & Ultrasound
31-32 w7ᵗʰRoutine, repeat anatomy + echo
33-34 w8ᵗʰRoutine, CBC, LFT/RFT, ECG, NST
35-36 w9ᵗʰRoutine, GBS, UA, level-II, NST
37 w10ᵗʰRoutine, CBC, UA, pre-transfusion panel, ferritin, coagulation, LFT/RFT, lipids, electrolytes, NST
38 w11ᵗʰRoutine, UA, level-II, NST
39 w12ᵗʰRoutine, UA, NST
40 w13ᵗʰRoutine, UA, level-II, ECG, NST
Reminder: The above is for low-risk pregnancies; follow your doctor’s advice if high-risk or special conditions apply.

Why choose PreMami due-date calculator?

Three modes

LMP, ovulation day and IVF transfer—covering every conception route

Smart cycle correction

Auto-adjusts for cycle length, giving a more accurate EDD

Daily growth reminder

Real-time fetal size, fruit comparison and weight estimate

Visit schedule

Auto-generates personalised prenatal check-up plan

How due-date calculation works

Understand the formulas, error sources & correction tips in 3 minutes

Common formulas & when to use
MethodFormulaForError
LMPLMP + 280 dRegular cycles (21-35 d)±2 w
OvulationOvulation + 266 dOPK/BBT/US confirmed±1 w
IVFTransfer + 263/261 dART pregnancies±3 d
UltrasoundCRL-based GA back-calcIrregular cycles or >7 w±5 d
Why the date may still be off
  • Early/late ovulation (stress, drugs, travel)
  • Implantation variation (6-12 d)
  • Untypical cycle length not corrected
  • Multiple pregnancy—uterus stretches faster; 37 w = full term
Tips to improve accuracy

Day 1 = first day of full flow, not spotting.

Count 6 recent natural cycles (off hormones) and use the median.

GA by CRL has the smallest error and can “lock” your theoretical LMP.

Twins are full term at 37 w; have everything ready by 32 w.

How to use the due-date calculator

Pregnancy lasts about 40 weeks (9 months and 7 days). The calculator estimates your gestational age and baby’s birthday from the first day of your last menstrual period (LMP)—the world-wide standard. Track fetal growth and get ready for delivery.

Key milestones

  • Week 5: Gestational sac visible; morning sickness may start.
  • Late week 6: Heart beat detectable; miscarriage risk drops.
  • Week 13: Enter relatively safe zone.
  • Week 16: Placenta complete; stable 2ⁿᵈ trimester.
  • Weeks 18-20: First foetal movements; baby hears sound.
  • Week 28: Position begins to fix; check for breech.
  • Week 37+: Full term; labour may begin any time.
  • Week 40: Theoretical due date.

Manual calculation (Naegele’s rule)

  1. Subtract 3 months (or add 9) from the LMP month → baby birth month.
  2. Add 7 days to the LMP calendar date → baby birth date.

Example: LMP Oct 5 → 10 − 3 = 7, 5 + 7 = 12, EDD ≈ next year July 12.

Reminder: EDD is only an estimate for planning check-ups and delivery. If cycles are irregular or high-risk factors exist, confirm GA with an early ultrasound and follow your doctor’s advice.

FAQ

Medically 37 w – 42 w is “term”. Organs are mature at 37 w, but lungs benefit from 39 w. Use the calculator, then prepare for delivery once you reach 37 w.

Global standard counts from first day of LMP, not intercourse or ovulation, hence the +280 d rule. Irregular cycles can be corrected with ovulation or ultrasound data.

Only ~5 % deliver on the EDD; 90 % arrive between 37-42 w, ±2 w is normal. Early-scan or IVF-based dates are more precise.

Enter your average cycle length (e.g. 35 d) and the tool will auto-correct; or use an early-scan CRL to back-calculate the “true LMP”.

Input the actual transfer date and select embryo age: day-3 add 263 d, day-5 add 261 d. Our IVF calculator does it automatically.

Twins are full term at 37 w; most deliver 35-38 w. The tool switches the full-term mark to 37 w and tightens the visit schedule.

Standard timetable: 12 w NT, 16 w quad test, 20 w anatomy scan, 24 w OGTT, 28 w HBV recheck, 32 w NST, then weekly after 36 w. High-risk mums need extra visits.

Bloody show, regular contractions (every 5-6 min lasting 30 s), or rupture of membranes. Use our contraction timer; go to hospital if 3 in 10 min or waters break.