Due Date & Gestational Age
Estimate due date and gestational age using last period and regular cycle length.
Pre-filled values are examples, not personal facts or current local rates. Replace them before calculating.
Calculation method and references
EDD = LMP + 280 days + (cycle − 28). Estimated gestation uses the adjusted anchor; ultrasound dating takes precedence.
NHS: due date and clinical dating
Method reviewed: 2026-09-08
Your entries remain in this browser. No account, upload, tracking of form values or persistent saving. Export only when you choose.
{"fields":[{"key":"lastPeriod","label":["末次月经第一天","First day of last period"],"type":"date","value":"2026-07-01"},{"key":"cycle","label":["规律周期长度（天）","Regular cycle length (days)"],"type":"number","value":28,"min":21,"max":35,"step":1},{"key":"asOf","label":["查询日期","As-of date"],"type":"date","value":"2026-09-08"},{"key":"regular","label":["日期可靠且周期规律（非辅助生殖）","Reliable date and regular cycles; not IVF"],"type":"select","options":[["yes",["是","Yes"]],["no",["否","No"]]],"value":"yes"}],"title":["预产期与孕周估算","Due Date & Gestational Age"],"engine":"pregnancy-dates","scope":["日期不确定、周期不规律或辅助生殖请采用产科给定日期。仅估算，不判断怀孕、胎儿健康或选择分娩时机。","Uncertain dates, irregular cycles and assisted reproduction need clinical dating. Not a pregnancy test or assessment of fetal health."]}