PediTools growth calculators (beta)

Fenton 2025 growth calculator for preterm infants

Sex

Male Female

Gestational age

Weight (grams)

Head circumference (cm)

Length (cm)

Dates: LMP, due date, birth, day of life

Last menstrual period

Due date

Date of birth

Gestation at birth

Analysis date

Age in days on date

Day of life on date

Reset form

Preterm

Infants and young children

Children and adolescents (2–20 years)

Special populations

Arm circumference and skinfolds

Legacy charts

Preterm infants, 22½ to 50 weeks: weight, length and head circumference. Based on infants without abnormal fetal growth.

From a meta-analysis of infants without abnormal fetal growth, joined to the WHO growth standard after term.

Weight Z-scores beyond ±3 use WHO's restricted LMS method, as in the authors' calculator.

Enter the bare minimum:
- Can enter just sex, gestational age, and growth metrics, without dates, if desired
- If only a gestational age is entered, the 50th percentile values will be displayed
- If any dates are entered, the other dates and ages are calculated where possible
Gestational age and dates can be calculated under Dates: LMP, due date, birth, day of life.
Gestational age: weeks and days, e.g. 30 3/7 (30+3 also works)
Weight: grams. To enter pounds and ounces, enter e.g. 8-4 for 8 lb 4 oz
Head circumference and length: cm. For inches, enter e.g. 20"