IQ Score Conversion Chart: Wechsler, Stanford-Binet & Cattell (2026)

IQ Score Conversion Chart

Convert your score between Wechsler (SD15), Stanford-Binet (SD16), and Cattell (SD24) scales. Not sure which test you took? Check our Wechsler IQ test guide or Stanford-Binet guide first.

Looking for percentiles instead? This page converts a score between different test scales so you can find the equivalent number on another scale. If you just want to know what percentile or rarity a single score represents, use our IQ Percentile & Rarity Chart instead.

Convert Your Score

Which test did you take?

Your score

Wechsler (SD15)	Stanford-Binet Older Ed. (SD16)	Cattell (SD24)
180	185	228
175	180	220
170	175	212
165	169	204
160Extremely Rare	164	196
159	163	194
158	162	193
157	161	191
156	160	190
155	159	188
154	158	186
153	157	185
152	155	183
151	154	182
150	153	180
149	152	178
148	151	177
147	150	175
146	149	174
145Genius Level	148	172
144	147	170
143	146	169
142	145	167
141	144	166
140	143	164
139	142	162
138	141	161
137	139	159
136	138	158
135	137	156
134	136	154
133	135	153
132	134	151
131	133	150
130Very Superior / Mensa Cutoff	132	148
129	131	146
128	130	145
127	129	143
126	128	142
125	127	140
124	126	138
123	125	137
122	123	135
121	122	134
120	121	132
119	120	130
118	119	129
117	118	127
116	117	126
115High Average	116	124
114	115	122
113	114	121
112	113	119
111	112	118
110	111	116
109	110	114
108	109	113
107	107	111
106	106	110
105	105	108
104	104	106
103	103	105
102	102	103
101	101	102
100Average (Mean)	100	100
99	99	98
98	98	97
97	97	95
96	96	94
95	95	92
94	94	90
93	93	89
92	91	87
91	90	86
90	89	84
89	88	82
88	87	81
87	86	79
86	85	78
85Lower Average	84	76
84	83	74
83	82	73
82	81	71
81	80	70
80	79	68
79	78	66
78	77	65
77	75	63
76	74	62
75	73	60
74	72	58
73	71	57
72	70	55
71	69	54
70Borderline	68	52
65	63	44
60	57	36
55	52	28
50	47	20
45	41	12
40	36	4

Why IQ Scores Need Converting Between Scales

Every deviation IQ scale is centred on a mean of 100 — but they don't agree on how far scores spread out from that centre. The Wechsler scales (WAIS-IV, WISC-V), now the most widely used, set one standard deviation (SD) at 15 points. Older editions of the Stanford-Binet (Form L-M, and the 1960/1986 revisions) used an SD of 16. The Cattell Culture Fair Intelligence Test, used historically by some high-IQ societies, was deliberately normed to a much wider SD of 24 to spread scores further apart. Because of this, the same raw number means something completely different depending on which scale produced it — and the same underlying ability produces a different number on each scale.

The Classic Example: Mensa's 132 vs. 148

Mensa's qualifying threshold is the top 2% of the population — the same percentile, regardless of which test you take. On the Wechsler or modern Stanford-Binet (both SD15), that threshold lands at approximately 130. On the older Stanford-Binet (SD16), it's 132. On the Cattell scale (SD24), the identical percentile appears as roughly 148. All three numbers represent the exact same rank in the population — only the scale changes.

How the Conversion Works

Converting between scales is a simple z-score transformation: first calculate how many standard deviations your score sits from the mean on its original scale, then re-express that same distance using the target scale's SD. A score doesn't need to be recalculated from raw test data to be converted this way — the two numbers are mathematically equivalent positions on the normal curve.

Reading This Table

Find your score in the Wechsler (SD15) column on the left — this is the scale used by nearly all modern IQ tests, including WAIS-IV, WISC-V, and the current Stanford-Binet 5. The two columns to the right show what an equivalent score would look like if the same percentile rank were expressed on the older Stanford-Binet (SD16) scale or the wider Cattell (SD24) scale. If your score came from an SD16 or SD24 test instead, use the row where that column matches your score, then read the Wechsler-equivalent number on the left.

Methodology:
Conversions use the standard z-score transformation: z = (IQ_original − 100) / SD_original, then IQ_target = 100 + (z × SD_target). Wechsler and current Stanford-Binet 5 scores use SD = 15. Older Stanford-Binet editions (Form L-M, 1960/1986 revisions) use SD = 16. The Cattell Culture Fair Intelligence Test (Cattell III B) uses SD = 24. All values are rounded to the nearest whole point. This table assumes each scale follows a normal distribution centred on a mean of 100, which is the standard convention test publishers use when norming a scale.