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
Wechsler / Stanford-Binet 5 (SD 15)
Older Stanford-Binet (SD 16)
Cattell (SD 24)
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 = (IQoriginal − 100) / SDoriginal, then IQtarget = 100 + (z × SDtarget). 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.
