How to Use a Due Date Calculator Accurately

# How to Use a Due Date Calculator Accurately

Due date calculators give you a quick estimate of when your baby is likely to arrive. While no calculator can be 100% precise, using one in combination with a pregnancy tracker can greatly improve your planning and monitoring.

Why calculators are estimates

Most due date calculators use either the date of your last menstrual period (LMP) or an early ultrasound measurement. These methods provide an estimated date of delivery (EDD) but do not replace clinical assessment. A pregnancy tracker that logs LMP, cycle length, and ultrasound dates helps refine the estimate over time.

Best practices when using a due date calculator

• Enter accurate LMP and cycle length into the calculator.
• Record any ultrasound dates in your pregnancy tracker so you can compare results.
• Use the calculator result as a planning date, not an absolute deadline.

How a pregnancy tracker improves accuracy

When you pair a due date calculator with a pregnancy tracker you use both tools together: the calculator provides the initial EDD, and the tracker records changes (ultrasound updates, irregular cycles, conception dates) that inform your provider. A pregnancy tracker also helps you plan appointments, prepare checklists, and set reminders based on the calculator's estimate.

Practical tips

• Update your pregnancy tracker after every appointment.
• Keep a note of any bleeding, pain, or symptoms that might prompt re-evaluation.
• Use both the calculator and the pregnancy tracker for birth-prep checklists and hospital bag planning.

Using a due date calculator alongside a pregnancy tracker gives you both an evidence-based estimate and a running record you can trust and share with your care team.