Your odds, day by day
For informational purposes only. Not medical advice.
When is your due date?
Enter your estimated due date to get started
Enter your due date above
to see your labor probabilities
If you're searching for the most accurate labor predictor, the key is probability—not a single date. This calculator estimates your chance of spontaneous labour by day and by week using recent NHS and CDC birth data, then adjusts for personal factors that shift timing.
Our numbers are for spontaneous labour onset. That's useful for real-world planning: childcare, work handover, travel cut-offs, and hospital bag timing. If you're overdue and discussing induction, your actual delivery timing can differ from spontaneous probabilities.
Parity matters. First pregnancies tend to run slightly later, while second and third babies are often earlier on average. Use the personalisation settings to compare scenarios and see how your expected window moves.
If you prefer week-level planning, visit our week-by-week guide for clear probabilities at 37, 38, 39, 40, and 41+ weeks. It explains cumulative odds and why chances rise quickly after the due date.
The model is distribution-based and calibrated to observed birth timing data. In plain English: we estimate the population curve, then calculate your conditional probability given that you're still pregnant today. That gives a more realistic answer than a fixed due-date prediction.