Child Vaccination Schedule Calculator
Estimates the recommended age for a child's next vaccine dose based on the current age and the age at their last dose. Useful for parents and caregivers tracking immunization schedules.
Last updated: September 2026
Formula below · 3 sources (CDC, aap.org, healthychildren.org) · Updated Sep 2026
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About this calculator
Vaccination schedules follow fixed ages set by the CDC/ACIP. For each vaccine series this calculator lists the scheduled ages and returns the next one after the age at the child's last dose of that vaccine: DTaP at 2, 4 and 6 months, 15–18 months and 4–6 years (then Tdap at 11–12 years); MMR at 12–15 months and 4–6 years; polio (IPV) at 2 and 4 months, 6–18 months and 4–6 years; Hib at 2, 4 and 6 months and a 12–15-month booster (with the PedvaxHIB brand the 6-month dose is skipped). The result is the age in months when the next dose is due (for example 48 = the 4–6-year dose). If the child's current age is already more than a month past the end of the recommended window for that dose, the calculator says the dose is overdue, because the CDC catch-up schedule (with its minimum intervals) then applies. This is a general guidance tool and does not replace a healthcare provider's personalized schedule.
How to use
Say a child is currently 4 months old and received the last DTaP dose at 2 months. The next DTaP dose on the schedule after 2 months is at 4 months, so it is due now. If the child had the third DTaP dose at 6 months, the next is the 15–18-month booster (result 15). For MMR given at 12 months, the next dose is at 4–6 years (result 48). If a child is now 24 months old and the last DTaP was at 6 months, the 15–18-month dose is overdue and the calculator points you to the catch-up schedule.
Frequently asked questions
When should my baby get their next DTaP vaccine?
The DTaP vaccine is typically given at 2, 4, 6, and 15–18 months, with a booster between 4–6 years. This calculator returns the next of those scheduled ages after the child's last DTaP dose. These dates align with CDC recommendations but your child's doctor may adjust timing based on illness or missed doses. Always confirm with your pediatrician before scheduling vaccinations.
What happens if my child misses a scheduled vaccination date?
Missing a vaccination date does not mean starting the series over. Most vaccine schedules can be caught up using an accelerated catch-up schedule recommended by the CDC. The intervals between catch-up doses are often shorter than the standard schedule. A pediatrician or public health nurse can calculate the correct catch-up timing; this calculator is designed for standard on-time scheduling only.
How accurate is an online vaccination schedule calculator?
Online calculators like this one provide a general estimate based on widely accepted immunization guidelines. They are useful for keeping track of upcoming appointments and understanding typical schedules. However, individual circumstances such as prematurity, immune conditions, or missed doses can change the recommended timing. Always verify the output with your child's healthcare provider or official national immunization records.