Cognitive, developmental, and adaptive batteries are all normed by exact age. This free calculator gives you the precise years;months;days the scoring software expects — computed with the borrow-30 method.
Why exact age drives the score
Every age-normed instrument you administer converts raw scores to standard scores using the child's exact age. A miscalculated age pulls from the wrong norm table — quietly shifting the standard score and percentile, and with them an eligibility determination. The publisher convention is borrow-30 (every month = 30 days), not ordinary calendar math.
Instruments this matters for
- WISC-V — Wechsler Intelligence Scale for Children
- WPPSI-IV — Wechsler Preschool & Primary Scale of Intelligence
- Bayley-4 — Bayley Scales of Infant & Toddler Development
- Vineland-3 — Adaptive Behavior Scales
- KABC-II, WIAT-4, and other Q-global–scored batteries
What this tool gives you
- Exact years;months;days in the borrow-30 format the manuals and Q-global expect
- A settable test date for the exact day of the evaluation
- Deterministic, unit-tested math — never an AI approximation
- 100% private: nothing you enter is transmitted, tracked, or shared
Why not a generic calculator or ChatGPT? They use calendar math, not borrow-30 — here's the difference →
Built for your assessments
- Speech-Language Pathologists
- School Psychologists
- Pediatric OTs & PTs
- Early Intervention
Right age band, right score — free.
Free iOS / Mac app, or use it in your browser. No ads, no accounts, no subscription.
