Pick a calculator
Choose by task; browse all if you are unsure.
01 · TOOLS
All Calculators
01
Due Date Calculator
Estimate your due date by adding 280 days to the first day of your last period.
免费 · Free02
Pregnancy Weeks Calculator
Convert days since your last period into pregnancy weeks, days and trimester.
免费 · Free03
Conception Date Calculator
Estimate the conception date by counting back about 266 days from the due date.
免费 · Free02 · HOW
How to use
Enter dimensions
Units sit next to each input; results convert automatically.
Read result and assumptions
Waste allowance is included; verify before ordering.
03 · WHY
Why use this site
01
Verifiable math
Every page shows the formula, assumptions and margin. No black box.
02
No signup
Open and calculate. Inputs stay in your browser and are not uploaded.
03
Localized
Chinese and English switch automatically, with units and rules adapted per market.
04 · FAQ
FAQ
How accurate is this?
Estimates follow public formulas with stated assumptions; verify high-stakes decisions on site.
Is it free?
All calculators are free today. Any future Pro tier will be priced on the page.
Do you store my inputs?
No. The math runs locally in your browser and is never submitted.