This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.

Fenton 2025 Growth Calculator / Fenton 2025 Growth Calculator

Weight, length, head circumference according to the third-generation Fenton curves (2025); expected weight gain

About this calculator

Percentiles and z-score of weight, length and head circumference according to Fenton 2025 (22–50 weeks postmenstrual) with integrated gestational age calculator, SGA/AGA/LGA classification at birth and the weekly weight gain needed to maintain the current percentile. The third-generation curves are based on a meta-analysis excluding children with abnormal fetal growth.

Postmenstrual age = gestational age at birth + age since birth. For classification at birth (SGA/AGA/LGA), completed weeks are customary; here the curves are interpolated to the day.

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Reference and license

Fenton 2025 – weight and head circumference 22.5–50 weeks; length 23.5–50 weeks.
Fenton TR et al. Fenton third-generation growth charts of preterm infants without abnormal fetal growth: a systematic review and meta-analysis. Paediatr Perinat Epidemiol. 2025;39:543–555. License: CC BY-NC-ND 4.0 (Dr. Tanis Fenton, University of Calgary) – non-commercial use only; commercial license via Innovate Calgary. LMS parameters of the Excel calculator v1.1 via a third-party mirror (github.com/zdenecek/perterm-percentiles-fenton); Calgary releases the original Excel only on request.. Source
Third generation of the Fenton curves (meta-analysis excluding children with abnormal fetal growth). The LMS values meet the official birth weight cutoffs from 2025 to 37 weeks to ≤ 1 %; from 38 weeks, the growth curve deliberately differs from the size-at-birth table (Calgary: “size-at-birth values differ from the growth charts > 36 weeks”). For classification at birth, completed weeks and the cutoff table are decisive; for follow-up monitoring, the exact postmenstrual age.

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Note

Calculation aid for healthcare professionals. Percentiles and z-scores describe the position of a measured value in the reference population; clinical assessment remains with the treating physician.

Frequently asked questions

What is new in the Fenton curves of 2025?

The third generation is based on a meta-analysis of seven population-based cohorts from 15 countries (4.8 million births, 22–42 weeks) that exclude children with abnormal fetal growth (depending on the cohort, e.g. hypertensive disorders of pregnancy, diabetes, multiple births, induced preterm births). In the curve data, the spread is therefore narrower than 2013; the medians are somewhat higher, at around 28 weeks.

Why does the classification at birth from 37 weeks differ from the curve?

Fenton distinguishes the growth chart (follow-up of preterm infants) from the birth size table (SGA/AGA/LGA per completed week). Near term, the curve transitions into postnatal growth, whereas birth sizes flatten out. For classification at birth from 37 weeks, the limit table under “Size at birth” is therefore authoritative.

Where do the Fenton 2025 curve data come from?

The LMS parameters correspond to the Excel calculator “2025 Fenton Growth Chart Clinical Calculator v1.1” of the University of Calgary (CC BY-NC-ND 4.0, non-commercial use). They were checked against the birth weight limits published by Calgary (deviation up to 37 weeks below 1 %).