Fitness & Health
Pregnancy Due Date Calculator
Estimate the expected due date from the last period.
Inputs
Adjust the assumptions to match your scenario. Results update instantly.
Results
Primary outputs and comparison insights are built from the current inputs.
Days remaining
238
Estimated days until the due date.
Weeks pregnant
6
Current estimated weeks of pregnancy.
Trimester (1-3)
1
Current trimester of pregnancy.
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How this calculator works
The Pregnancy Due Date Calculator estimates expected delivery date and current gestational age based on the last menstrual period. Enter days since last period and cycle length (days) to estimate days remaining, weeks pregnant, and trimester (1-3). The calculator updates instantly and adds a comparison table plus chart so you can test the sensitivity of the result before you use it in a decision.
Quick guide
Jump straight to the section you need, then return to the calculator.
Inputs
- Number of days since the first day of the last menstrual period.
- Average menstrual cycle length in days.
Outputs
- Estimated days until the due date.
- Current estimated weeks of pregnancy.
- Current trimester of pregnancy.
Assumptions
- Uses Naegele's rule.
- Actual due dates vary ±2 weeks.
Tips
- An ultrasound date is more accurate for dating.
- Only 5% of babies arrive exactly on the due date.
Formula guide
Use these formulas to audit the output or explain it to someone else.
1 formulas
Usage examples
Review a ready-made scenario, copy it, then tweak inputs to match your case.
Example
Early pregnancy check
Inputs
- Example input Days since last period: 56
- Example input Cycle length (days): 28
Outputs
- Example result Days remaining: 224
- Example result Weeks pregnant: 8
- Example result Trimester (1-3): 1
At 8 weeks, the first trimester is well underway and early prenatal care is important.
Due date by cycle length
| Cycle length (days) | Days remaining | Weeks pregnant |
|---|---|---|
| 25 | 235 | 6 |
| 26 | 236 | 6 |
| 28 | 238 | 6 |
| 30 | 240 | 6 |
| 32 | 242 | 6 |
Cycle length adjusts the due date by the same number of days.
Days remaining by cycle
Focus point
25
235
Position
#1 of 5
Original order
Share of total
19.73%
Total: 1,191
Cycle length adjusts the due date by the same number of days.
References
- Naegele's rule for due date estimation
- ACOG pregnancy dating guidelines
FAQ
Common questions
What does the Pregnancy Due Date Calculator do?
The Pregnancy Due Date Calculator estimates expected delivery date and current gestational age based on the last menstrual period. Enter days since last period and cycle length (days) to estimate days remaining, weeks pregnant, and trimester (1-3). The calculator updates instantly and adds a comparison table plus chart so you can test the sensitivity of the result before you use it in a decision. It is part of our fitness & health toolkit.
What inputs do I need?
Typical inputs include Number of days since the first day of the last menstrual period., Average menstrual cycle length in days..
How are the results calculated?
We follow the formulas and assumptions outlined in the "How this calculator works" section. You will see outputs like Estimated days until the due date., Current estimated weeks of pregnancy., Current trimester of pregnancy..
Can I share or download the results?
Use the Copy link or Print buttons to share your results. If a table or chart appears, you can download the data as CSV.
Is my data stored?
No. Calculations run in your browser and we do not store your inputs.
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