Next Immunization Calculator
Shows the age at which a child's next routine vaccine visit is due on the CDC childhood schedule, from the age at their last vaccine visit. Used by parents and nurses to stay on schedule with routine childhood vaccinations.
Last updated: September 2026
Formula below · 3 sources (CDC, aap.org, healthychildren.org) · Updated Sep 2026
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About this calculator
Routine childhood vaccines are grouped into well-child visits at fixed ages in the CDC/ACIP schedule: birth (hepatitis B), 2, 4 and 6 months (DTaP, IPV, Hib, PCV, rotavirus, hepatitis B), 12–15 months (MMR, varicella, hepatitis A, Hib and PCV boosters), 15–18 months (DTaP booster; second hepatitis A dose by 18–23 months), 4–6 years (DTaP, IPV, MMR, varicella boosters), 11–12 years (Tdap, HPV, MenACWY) and 16 years (MenACWY booster). This calculator takes the child's age at the last routine vaccine visit and returns the age in months of the next scheduled visit: after a dose at birth or 1 month the next is due at 2 months; then 4, 6, 12, 15 and 18 months; after 18 months the next is the 4–6-year visit (shown as 48 months); after that 11 years (132 months) and 16 years (192 months). A yearly flu vaccine is recommended for everyone from 6 months and is not shown. If doses have been missed, the CDC catch-up schedule (minimum intervals between doses) applies instead and a healthcare provider should plan the next steps.
How to use
A child is now 4 months old and had the last vaccines at the 2-month visit. Enter 2 as the age at the last vaccine visit: the next routine visit is at 4 months, so the child is due now (DTaP, IPV, Hib, PCV and rotavirus). Another example: after the 6-month vaccines the next routine visit is at 12 months (MMR, varicella, hepatitis A and boosters), not at 8 months. After the 15-month visit the next is at 18 months, and after 18 months the next is the 4–6-year visit (48 months).
Frequently asked questions
How do I know when my child's next vaccination is due?
Most routine childhood vaccines follow a 2-month interval during the first year of life, with doses typically due at 2, 4, 6, and 12–15 months. This calculator returns the next routine visit age from the CDC schedule (2, 4, 6, 12, 15, 18 months, then 4–6, 11–12 and 16 years). For a complete and personalized schedule, consult your pediatrician or use the CDC's official childhood immunization schedule, which accounts for all vaccines including annual flu shots and catch-up dosing. Vaccination records (immunization cards or electronic health records) are the most reliable reference.
What happens if a child misses a scheduled vaccination?
Missing a vaccine dose does not require restarting the entire series from the beginning. Health authorities provide official catch-up immunization schedules that specify minimum intervals between doses to safely resume the series. The CDC's catch-up schedule, available at cdc.gov, covers all vaccines for children aged 4 months through 18 years. It is important to resume vaccination as soon as possible to maintain protection, especially before daycare or school entry. A pediatrician or public health nurse can review the child's records and recommend the fastest safe path to being fully up-to-date.
Why are childhood vaccines given at 2-month intervals in the first year?
The 2-month interval is designed to allow the immune system sufficient time to mount a measurable primary response to the first dose before being boosted by the next. Infants are born with some maternal antibodies that wane in the first few months; the vaccination schedule is timed to build active immunity before this window of vulnerability widens. Giving doses too close together can blunt the immune response, while waiting too long leaves children unprotected during a period of high susceptibility to serious diseases like pertussis and Hib meningitis. The schedule is evidence-based and regularly reviewed by the CDC's Advisory Committee on Immunization Practices (ACIP).