Levels of giftedness by IQ

The rarity column is computed from the normal curve with a mean of 100 and a standard deviation of 15, the scale of every current major test. It shows how many children in a million you would expect in each band.

Gross built her bands while studying Australian children with very high scores, many of them measured on the old Stanford-Binet Form L-M. That test still allowed ratio-style scores, where a precocious young child could score far above what today's tests can produce. A "180" from that era and a "180" on a modern test are not the same claim; on a modern deviation scale a true 180 would be rarer than 1 in 20 million, and no current test is normed to measure it.

So organisations have redrawn the lines. The Davidson Institute, which runs a programme for very able children, says plainly that the levels are not universally agreed, and its Young Scholars programme sets its profoundly gifted bar around the 99.9th percentile, roughly 145, far below 180. Test publishers avoid the word gifted in their main tables: the WISC-V simply calls 130 and above "extremely high". The Stanford-Binet 5 uses "gifted or very advanced" and, above that, "very gifted or highly advanced".^[1]

Every test has a ceiling: a point beyond which getting everything right cannot raise the score further. Standard composite scores on today's main tests stop at 160. A child who answers every hard item correctly on several subtests has been shown to be at least that able, not how far beyond it.

Two fixes exist. Extended norms, such as those Pearson published for the WISC-V in 2019, let the tables continue upward when a child reaches the top scaled score of 19 on subtests; they were built with the help of psychologists who specialise in highly gifted children. The other is out-of-level testing, giving a younger child a test written for older children, which is how many talent searches identify the most able. Both are specialist tools, and a parent who suspects their child is far above 145 should ask for a psychologist experienced with them.

Precision also falls at the top. Each score carries a margin of error of several points, and the norm samples contain very few children at these levels: in 2,200 children you would expect about three above 145 and none above 160. Two children reported at 152 and 158 may not differ at all, which is another reason not to treat the band edges as sharp.

Most gifted programmes do not use any five-level scheme. They set one line, very often 130 (the 98th percentile), sometimes lower, and they increasingly look at more than one number: achievement tests, teacher ratings and work samples alongside an IQ test. On the WISC-V, many accept the General Ability Index instead of the Full Scale IQ, because it leaves out processing speed and working memory, where many able children are merely average. Our WISC-V guide for parents explains those numbers.

The bands matter more once a child is far above the line. A child at 160 differs from a child at 130 by as much as a child at 130 differs from one at 100, and the same classroom rarely suits both. That is the practical point of the levels: not ranking children, but noticing when the usual adjustments will not be enough.

The levels were written for children, where they guide schooling. For adults the labels are less useful, because nothing about adult life sorts people by band. The equivalent adult questions are usually "is my score high enough for Mensa?" (130 on the Wechsler scale; see high-IQ societies) and "what does my score mean?" (see what a good IQ is). If you recognise yourself in descriptions of gifted adults, the am I gifted? self-check is a reasonable next step, and a professional test is the only way to a number that counts.