IQ Score Chart — Scores, Percentiles, and z-Scores
Here is the IQ score chart people usually want: every reference score from 55 to 145 in five-point steps with its percentile and z-score, computed from the mean-100, SD-15 model. Type a score to highlight its row — 100 maps to the 50th percentile, 115 to the 84th, 130 to the 98th.
IQQuiz Editorial Team
- Full table, 55–145 in steps of 5
- 100 → 50% · 115 → 84.13% · 130 → 97.72%
- Copy any row's percentile text
The IQ score chart, ready to search
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The chart lists score, percentile, and z-score together — the three numbers usually scattered across sources. Enter a score to move the highlight, and use the copy button to export a plain-text line like 'IQ 115 ≈ 84.13th percentile on the common mean-100, SD-15 reference scale.'
Type a score, drag the slider, or tap a reference point (70 / 85 / 100 / 115 / 130).
| IQ score | Percentile | z-score |
|---|---|---|
| 145 | 99.87 | 3 |
| 140 | 99.62 | 2.67 |
| 135 | 99.02 | 2.33 |
| 130 | 97.72 | 2 |
| 125 | 95.22 | 1.67 |
| 120 | 90.88 | 1.33 |
| 115 | 84.13 | 1 |
| 110 | 74.75 | 0.67 |
| 105 | 63.06 | 0.33 |
| 100 ← | 50 | 0 |
| 95 | 36.94 | -0.33 |
| 90 | 25.25 | -0.67 |
| 85 | 15.87 | -1 |
| 80 | 9.12 | -1.33 |
| 75 | 4.78 | -1.67 |
| 70 | 2.28 | -2 |
| 65 | 0.98 | -2.33 |
| 60 | 0.38 | -2.67 |
| 55 | 0.13 | -3 |
z-score
+0
Percentile
50%
Reference band
Around the reference mean (upper half)
Range: 100 – 114
Reference model: normal distribution with mean 100 and standard deviation 15 — a common convention for standardized IQ scales. Publishers use different classifications and norms, so treat these bands as a reading aid for existing standardized scores, not as a clinical or diagnostic statement. Scores from the practice quizzes on this site are accuracy percentages, not standardized IQ scores.
How to read the IQ score chart
Each row of the IQ score chart answers one question: where does this score sit? The percentile column gives the intuitive answer — the share of the reference distribution at or below the score. The z-score column gives the mechanical one — how many standard deviations the score sits from the mean of 100, at 15 points per deviation. Three columns, one answer: that is what an IQ score chart owes you.
Anchor on three rows and the whole chart falls into place. IQ 100 sits at exactly the 50th percentile: it is the mean by construction. IQ 115 is z = +1, the 84.13th percentile. IQ 130 is z = +2, the 97.72nd percentile. Symmetric rows mirror below: 85 lands at the 15.87th percentile and 70 at the 2.28th. Every other row interpolates the same curve. Anchor on those rows and the IQ score chart reads itself.
Notice what the chart's smoothness implies: percentile gaps stretch at the edges. From 100 to 105 covers about 13 percentile points; from 130 to 135 covers fewer than one and a half. Near the tails, identical score differences mean wildly different rarity — the single most misread property of any IQ score chart. Read the IQ score chart top-down once and the stretching-tails pattern is unmistakable. Tail stretching is the most misread row of any IQ score chart.
- IQ 100 → z = 0 → 50.00th percentile (the mean)
- IQ 115 → z = +1 → 84.13th percentile
- IQ 130 → z = +2 → 97.72nd percentile
- IQ 85 → z = −1 → 15.87th percentile
- IQ 70 → z = −2 → 2.28th percentile
Where the numbers come from
Every value in this IQ score chart is computed, not copied from a mood board. The model is the normal distribution with mean 100 and standard deviation 15; a score's z is (score − 100) ÷ 15, and its percentile is the standard normal cumulative distribution at that z, times 100. The table shows percentiles to two decimals so you can verify the canonical anchors: 2.28, 15.87, 50.00, 84.13, 97.72. A computed IQ score chart shows its method, and this one does.
Two conventions keep the chart honest. Percentiles are 'at or below' — the 84.13th percentile means at or above about 84 percent of the reference distribution. And rows step by five points, which is fine-grained enough for orientation while acknowledging that individual reports carry a few points of measurement uncertainty anyway; the five-point grid matches how the numbers are actually used. An honest IQ score chart shows its method, and this one does. Two conventions keep this IQ score chart honest.
If you prefer the same information as a picture, the interactive chart page plots the scale as a draggable axis, and the bell-curve page shades the areas the percentiles represent. Same engine, same values — three presentations because readers differ. Three views, one IQ score chart worth of numbers. Same engine, three views — the IQ score chart is the searchable one.
IQ score chart math, one line at a time
Take IQ 115. z = (115 − 100) ÷ 15 = 1. The standard normal CDF at z = 1 is 0.8413, so the percentile is 84.13. Take IQ 130: z = 2, CDF = 0.9772, percentile 97.72. Every row of the IQ score chart is exactly this computation, which is why the values match every properly built table you will find. That is every row of the IQ score chart, in one line of arithmetic.
Reading percentiles without confusion
A percentile is not a percentage correct and not a grade. The 84th percentile says nothing about how many questions someone answered right — it says where the score sits in a distribution. Practice-quiz accuracy from this site's tests, for instance, never appears on this IQ score chart, because the two quantities live on different scales entirely. Quiz accuracy never appears on an IQ score chart.
Using the chart for real reports
The chart's best use is interpreting a score you already hold — from a professionally administered test. Read the row, note the percentile, and remember the two cautions professionals apply. First, reports include confidence intervals: a score of 112 could plausibly have come from a true level a few points either side. Second, one score is one sample of performance on one day; important decisions use converging evidence, never a single row of a table. Used that way, the IQ score chart replaces guesswork with a two-decimal answer. Used that way, the IQ score chart replaces guesswork with two decimals.
The chart is deliberately not a scoreboard for comparing people. Its unit of analysis is a score; people are considerably more interesting than their position on one distribution. Used as a reading aid — what does this number mean — the IQ score chart is precise, quick, and complete. Used as a ranking of humans, it is misused. Its unit is a score — the IQ score chart ranks no one.
Related pages extend the same model: the ranges page bins the chart into bands, the levels page orders those bands as a ladder, and the scale page walks through the underlying mean-and-deviation logic step by step. All of them compute from the same distribution as this chart, so the numbers agree everywhere. Every sibling page re-slices this IQ score chart rather than re-inventing it. Every sibling page re-slices this IQ score chart, never re-invents it.
Keep exploring
Sources & further reading
Editorial standard: practice scores are never converted into IQ numbers. The score tools use the common reference model — mean 100, standard deviation 15, where ±1σ covers ≈ 68.27% and ±2σ covers ≈ 95.45% of the distribution (IQ 115 ≈ 84.13th percentile, IQ 130 ≈ 97.72nd). All figures are computed from the standard normal distribution and verified by automated checks.
Frequently asked questions
What percentile is an IQ of 120?
On the mean-100, SD-15 model, z = (120 − 100) ÷ 15 ≈ 1.33, which is about the 91st percentile. Type 120 into the chart above and the row highlights instantly with the exact value. The IQ score chart handles any score in range the same way. The IQ score chart handles any score in range the same way.
Is this IQ score chart the same for every test?
The chart follows the common deviation convention — mean 100, SD 15 — used by most modern tests. Some instruments use other standard deviations, so always confirm the scale a given report follows before reading percentiles from this table.
Can I convert my quiz accuracy using the chart?
No. Accuracy on practice quizzes is a percentage of items answered correctly — a different quantity from a normed score. The IQ score chart interprets standardized scores only; the two scales never mix. Accuracy and the IQ score chart live on different scales.
Why do small score differences mean big percentile jumps near 100?
Because the normal distribution is densest at its center: many scores crowd near the mean, so five points there move the percentile a lot. Near the tails the curve flattens, so the same five points move the percentile very little — the chart makes this visible row by row. The IQ score chart makes that density gradient visible row by row. Row by row, the IQ score chart makes that gradient visible.