Iowa Assessment Scores Explained: Percentiles, Standard Scores, 2024 Norms

There is no single good Iowa Assessments score, because the figure that counts is a percentile for the student's grade and testing season. Riverside's guide treats national percentile ranks of 25 to 75 as the on-grade-level band, and every higher or lower line, including a gifted program's, is that program's own rule. The Iowa standard score is a separate thing: a growth scale on which 200 is the typical spring grade 4 result, not a mark out of 100 and not an IQ. Since August 2025 the default reference group has been Riverside's new 2024 norms, so a percentile on this year's report is measured against a different group from last year's.

What are the Iowa Assessments?

The Iowa Assessments are achievement tests for kindergarten to grade 12, published by Riverside Insights. Riverside says the series was first developed in 1935 by researchers at the University of Iowa, and many schools and gifted programs still use the older name: the Davidson Institute lists it as the Iowa Test of Basic Skills, or ITBS. Riverside describes Forms E, F and G as equivalent and built to the same blueprint, and the test is organised in levels tied to grade, from Level 9 for grade 3 to Level 14 for grade 8. Riverside pairs it with the Cognitive Abilities Test (CogAT), which measures reasoning rather than schooling, and our guide to CogAT and NNAT scores covers that side.

What are the 2024 Iowa norms?

Riverside announced new post-pandemic norms for the Iowa Assessments on 25 August 2025. They are built from a nationally representative sample of 4.6 million student records from public and private schools. Its scoring order form, revised on 1 August 2025, says the default norm year for Iowa Assessments Forms E, F and G, and for CogAT Forms 7 and 8, is 2024, and that tests are scored with 2024 norms unless the 2017 option is selected. CogAT received matching 2024 norms from more than 2.8 million assessments. Riverside's announcement also says high-performing students have rebounded more quickly than their lower-performing peers; that is the publisher's claim, and we have not seen the underlying tables.

Why this matters to a parent: a percentile is a rank within a reference group, and a new group moves the ranks. Sample reports still online show the 2017 norms, and the Riverside score guide in circulation was written for the 2011 norms. The spring median standard scores quoted below come from that older guide and may have shifted. Find the norm year printed on the report before comparing it with last year's, or with a chart on a prep site.

What do the Iowa score types mean?

Riverside's own definitions, from its score description page and its Score Interpretation Guide for Levels 9 to 14, give five main scores:

• National percentile rank (NPR): 1 to 99, the share of students in the norm group, same grade and same time of year, who scored at or below the student. The guide says plainly not to average percentile ranks
• Standard score (SS): a position on a growth scale, set by giving 200 to the median of spring grade 4 and 250 to the median of spring grade 8. In the 2011-norm guide the spring medians run from 130 in kindergarten to 150, 168, 185, 200, 214, 227, 239 and 250 in grades 1 to 8, and 260 in grade 9
• Grade equivalent (GE): the grade and month at which the typical student gets that score. The guide warns that a GE of 7.8 does not mean a child can do late seventh-grade work, and calls GEs poorly suited to showing standing within a group
• Normal curve equivalent (NCE): 1 to 99 with a mean of 50 and a standard deviation of 21.06, built so that, unlike percentile ranks, it can be averaged
• Stanine: 1 to 9 with an average of 5, a coarse band. The guide's own example puts percentile ranks 24 and 39 in stanine 4, while 23 falls in stanine 3

The standard score is the one that trips people up, because it looks like an IQ. It is not on that scale. Riverside defines it by location on an achievement continuum and states no mean or standard deviation; a standard score of 130 is the median of a spring kindergartner, and 250 is the median of a spring eighth-grader. Our explainer on the SD-15 and SD-16 IQ scales shows what a mean-100 scale actually fixes, which the Iowa standard score does not.

What is a good Iowa test score?

In Riverside's guide the on-grade-level band is percentile ranks 25 to 75. For grade 3 reading that is standard scores 170 to 204 around a median of 185, and for grade 8 it is 219 to 279 around a median of 250. Stanines are the same ranks in nine bands, on the standard 4, 7, 12, 17, 20, 17, 12, 7 and 4 per cent split:

• Stanines 1 to 3: percentile ranks up to 23, below the on-grade-level band
• Stanines 4 to 6: percentile ranks 24 to 77, the middle of the distribution
• Stanine 7: percentile ranks 78 to 89
• Stanine 8: percentile ranks 90 to 96
• Stanine 9: percentile ranks 97 to 99, the top 4 per cent of the norm group

Which of these is good enough depends on what the score is for. Nothing in Riverside's material sets a pass mark; the cutoffs below belong to the programs that use the test. For tests built the same way, see our guides to CAT4 scores, ISEE scores and MAP Growth scores.

What Iowa score do gifted programs ask for?

We found no 99th-percentile Iowa rule on a primary district page, so we checked what we could. The Neenah Joint School District in Wisconsin places students in gifted and talented services on a CogAT total, verbal or quantitative score of 130 or higher plus a percentile rank of 96 or higher in reading or maths. Its magnet program uses both tests: a CogAT total reasoning score of 135 to 139 with the 80th percentile or higher on the Iowa total battery, or 130 to 134 with the 85th or higher, and it ranks applicants by twice the CogAT total plus the Iowa total, so the ability test counts double. The district itself calls CogAT a full-range IQ test.

The Davidson Institute's Young Scholars program works differently. It accepts the ITBS only from a Davidson-specific administration, run with Northwestern University's Center for Talent Development, and asks applicants to meet or exceed the cutoff on at least three of four subtests, plus three work samples. For Grade 3 the cutoffs are 281 in reading, 302 in written expression, 274 in maths and 289 in science; for Grade 5 they are 311, 332, 305 and 318. The page does not label them as standard scores or percentiles, but they sit well above the grade 8 spring median of 250, which points to an above-grade-level test. That is our inference, not Davidson's wording. Its separate route for individually given IQ tests, such as the WISC-V, asks for a standard score of 145 or higher. Another school test used in gifted screening is i-Ready, for which one Ohio district asks for the 95th percentile, as i-Ready scores by grade level reports.

Is the Iowa Assessments an IQ test?

No. Riverside describes the series as measuring student achievement and growth against learning standards, and sells CogAT for ability. We found no sentence from Riverside or the University of Iowa that says "not an IQ test", so that is our reading of what the publisher says the test measures and how it uses the two together. The telling detail is the direction. Riverside reports a predicted Iowa standard score and a predicted percentile rank from a student's CogAT results, plus difference scores of observed minus predicted. The ability test is the input and the Iowa result is the thing being predicted. A chart that turns an Iowa score into an IQ has the arrow backwards, and we found no such conversion in Riverside's guides. Our overview of achievement tests versus IQ tests explains the difference.

A percentile can still be written on the IQ scale as arithmetic. On a mean-100, standard-deviation-15 scale the 75th percentile is 110, the 90th is 119, the 95th is 125, the 97th is 128 and the 99th is 135. CogAT's Standard Age Score has a mean of 100 and a standard deviation of 16 by Riverside's definition, where the same ranks are 111, 121, 126, 130 and 137. These are positions in a rank order, not IQ results: an Iowa percentile ranks achievement against same-grade peers, and the IQ percentile calculator gives the same figures for any rank.

How should you read an Iowa report?

• Find the norm year and the testing date before comparing with a previous year
• Compare like with like: the NPR is for the same grade and time of year, and Riverside offers local norms for a school's own comparison group
• Do not average percentile ranks; average standard scores or NCEs if one number is needed
• Treat a stanine as a band, since percentile ranks 23 and 24 fall in different stanines
• Read a grade equivalent as typical performance, not as proof of what a child can do in that grade
• For a gifted application, ask the program in writing which test, subtest, score type and norm year it uses

The IQ Metrics test reports on the standard scale, the kids IQ test covers younger test-takers, and the IQ bell curve shows where a result sits. For how school achievement relates to ability, see our note on whether IQ predicts school success and our piece on universal screening for gifted programs.

Common questions