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Earth Bondhon Author
Earth Bondhon
CalculatorToolsProjectExpert
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Małgorzata Koperska, MD Steven Wooding
Last updated: November 26, 2025

Pregnancy Calculator | Estimate Due Date & Pregnancy Week

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Pregnancy Calculator

Pregnancy Calculator

Use our Pregnancy Calculator to find your due date, current week, and conception day. Track your pregnancy progress easily from the first day of your last perio...

pregnancy weight gain calculator​

A Pregnancy Calculator will give you an estimate of your due date and your current gestational age, depending on the first day of your last period. It uses the Naegele Rule and adds 280 days (40 weeks) to such date. The calculator also provides an estimated date of conception and a way of monitoring the progress of the pregnancy week by week, and as such is a valuable tool for a pregnant couple.

Work & Installation — Input to Output Summary:

Input:

  • Age (years)
  • Sex (male/female)
  • Height (cm or in)
  • Weight (kg or lbs)
  • Activity Level (e.g., sedentary, lightly active, moderately active, very active)
  • Process / Formula:
    Many calculators are based on formulas like the Harris‑Benedict equation for BMR:
    \( BMR_{men}= 66.47 +(13.75 \times wight_{kg}) + (5.003 \times height_{cm}) \times (6.755 \times age) \)
    where ActivityFactor might be: 1.2 (sedentary), 1.375 (light), 1.55 (moderate), 1.725 (very active), etc.

Output:

  • Estimated BMR (calories per day at rest)
  • Estimated TDEE (calories per day accounting for activity)
  • Suggested calorie intake to maintain weight (≈ TDEE)
  • Suggested calorie intake to lose weight (e.g., TDEE – 500 kcal/day) or to gain weight (TDEE + 500 kcal/day)

Example Data Table:

Activity Level Multiplier Estimated Daily Calories
Sedentary (little or no exercise) 1.2 BMR × 1.2
Lightly active (light exercise/sports 1-3 days/week) 1.375 BMR × 1.375
Moderately active (moderate exercise/sports 3-5 days/week) 1.55 BMR × 1.55
Very active (hard exercise/sports 6-7 days/week) 1.725 BMR × 1.725

Testing and Final Adjustments

Test the calculator using various profiles (young/ old, male/ female, various weights/ heights) and see that the BMR/ TDEE estimates are in line with those provided in the literature. Check the unit conversion (kg ⌄ lbs, cm ⌄ in). Make sure the input values are realistic (age bigger than 10, height bigger than 100 cm, weight bigger than 30 kg). Enable users to alternate among the modes of maintenance, weight loss, weight gain, and set calorie goals. Include field tool-tips (e.g., the description of the activity level that best suits your daily routine). Outputs in colour-codes (maintenance (green) and a slight change (yellow) and a large deficit/surplus (red). Appendix Aa disclaimer: it is not a medical prescription but an estimate of a medical prescription. Make sure that you use keywords in your low-competition list in headings, buttons, and meta descriptions as they come naturally. Mobile input to be optimized, numeric keypad with minimum scrolling. Lastly, the speed of the check pages and that they load quickly on devices that are popular in Bangladesh and other places.

Frequently Asked Questions - Pregnancy Calculator:

What is a pregnancy calculator?

It estimates your due date, conception date, and pregnancy week using your last menstrual period (LMP).

How does the pregnancy calculator work?

It adds 280 days (40 weeks) to the first day of your last menstrual period to estimate your due date.

What is Naegele’s Rule?

A formula used to estimate a baby’s due date by adding 7 days to LMP and 9 months ahead.

How accurate is this calculator?

It provides an estimate; actual due date may vary depending on ovulation and medical assessment.

Can irregular cycles affect accuracy?

Yes, irregular cycles may shift ovulation timing, altering the predicted due date.

Can I use it if I don’t know my LMP?

It’s less accurate; consult your doctor for an ultrasound-based due date.

What is the gestational age?

The number of weeks since the first day of your last menstrual period.

Can this help plan prenatal visits?

Yes, it helps schedule checkups according to pregnancy milestones.

Does every pregnancy last 40 weeks?

Most last about 38–42 weeks; 40 weeks is the standard average.

Can I track trimesters with this tool?

Yes, it divides your pregnancy into three trimesters for better monitoring.

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Earth Bondhon

Earth Bondhon

Calculator Tools Project

Md. Jony Islam is a highly skilled professional with expertise in electronics, electrical, mechanical, and civil engineering, as well as finance. Specializing intransformer service and maintenance for 33/11kV substations, he ensures reliable and efficient electrical systems. His mechanical engineering skills drive innovative designs, while his financial acumen supports effective project budgeting. With a strong foundation in civil engineering, he contributes to robust infrastructure development. Md. Jony Islam's multidisciplinary approach ensures efficiency, quality, and reliability across all projects.