Intolerance of Uncertainty Scale – 12 (IUS-12): A Full Guide for Researchers and Clinicians
Published
The IUS-12 is a 12-item self-report measure of intolerance of uncertainty with two factors. Learn its scoring, reliability, versions and research uses.
Introduction
The Intolerance of Uncertainty Scale – 12 (IUS-12) is a 12-item self-report measure of intolerance of uncertainty: the tendency to find the possibility of a negative event unacceptable, however unlikely it is. R. Nicholas Carleton, Peter J. Norton and Gordon J. G. Asmundson published it in 2007. It has received more than 3,300 citations.
The study appeared in the Journal of Anxiety Disorders. The developers shortened the original 27-item IUS to create a more psychometrically stable and efficient measure. This guide explains the IUS-12's two factors, scoring, evidence and related versions.
Key Features of the IUS-12
Purpose and Use
The IUS-12 measures intolerance of uncertainty. Specifically, it captures a person's tendency to consider the possibility of a negative event unacceptable, regardless of its probability. The developers designed it as a more stable and efficient alternative to the 27-item IUS.
Target Population
The IUS-12 is intended for adults aged 18 and older. The original development used two undergraduate samples.
Structure
The IUS-12 contains 12 items about reactions to uncertainty, ambiguous situations, unforeseen and future events, incomplete information, surprises, and uncertainty that interferes with action. The items form two factors:
Prospective Anxiety (7 items)Inhibitory Anxiety (5 items)Scoring Method
Respondents rate each item on a 5-point Likert scale from 1 (not at all characteristic of me) to 5 (entirely characteristic of me).
Total score: the sum of the 12 items, from 12 to 60, used to evaluate general intolerance of uncertainty.Factor scores: the sums of the 7 Prospective Anxiety items and the 5 Inhibitory Anxiety items.Interpretation: higher scores indicate greater intolerance of uncertainty.Administration Format
The IUS-12 is a self-report questionnaire, so respondents complete it themselves using the 5-point scale.
Applications of the IUS-12
The IUS-12 is widely used in anxiety and mental health research:
Anxiety and worry research: measuring intolerance of uncertainty as a factor in anxiety.Specific populations: researchers have validated it in pregnant people and after acquired brain injury.Brief assessment: providing a 12-item alternative to the original 27-item IUS.Languages and availability
Besides the original English version, adaptations include:
Mexican Spanish: the IUS-12MSwedish: a Swedish IUS-12 (PDF)French: an adaptation and validation of the Intolerance to Uncertainty Scale-RevisedReliability and Validity
The original development study showed strong internal consistency and a stable two-factor structure across two undergraduate samples. Later studies have tested the scale in new groups.
Validation studies:
Fearing the unknown: a short version of the Intolerance of Uncertainty Scale (2007): study linkFrench adaptation and validation of the Intolerance to Uncertainty Scale-Revised (2023): study linkValidation of the IUS-12 in a sample of pregnant people (2025): study linkMeasuring intolerance of uncertainty after acquired brain injury with the IUS-12 (2023): study linkLimitations and Considerations
Keep these points in mind:
Clinical populations: the authors noted that clinical validity needed further investigation.Other languages and populations: psychometric properties across languages and populations also needed more study.Debated factor structure: state clearly whether you use the total score, the two subscale scores or a specific factor model.Other Versions And Related Questionnaires
The IUS family includes longer and shorter versions:
IUS (27 items): the original scale; see the psychometric properties of the English versionIUS-6: an ultra-brief versionIUS-5: a short form in initial developmentIUS-4: an ultra-brief measureThese questionnaires are related:
Beck Anxiety Inventory (BAI); see the ResRef BAI guideGeneralized Anxiety Disorder Questionnaire-IV (GADQ-IV)Penn State Worry Questionnaire (PSWQ); see the ResRef PSWQ guideAdditional Resources
The original article: linkFor inquiries, contact the corresponding author, R. Nicholas Carleton, Anxiety and Illness Behaviours Laboratory, University of Regina, Canada, at carletor@uregina.ca.Browse more anxiety questionnaires in the ResRef database.Frequently Asked Questions (FAQ)
What does the IUS-12 measure?The IUS-12 measures intolerance of uncertainty, the tendency to find possible negative events unacceptable regardless of their probability, through Prospective Anxiety and Inhibitory Anxiety factors.
How is the IUS-12 scored?Each item is rated from 1 to 5. Adding all 12 items gives a total from 12 to 60, and the two factor scores are the sums of their 7 and 5 items. Higher scores mean greater intolerance.
Should I use the IUS-12 total or subscale scores?Both are possible. Because the factor structure has been debated, researchers should state clearly whether they use the total score, the two subscale scores or a specific factor model.
How is the IUS-12 different from the original IUS?The IUS-12 shortens the original 27-item IUS to 12 items, aiming for a more psychometrically stable and efficient measure of the same construct.
A Word from ResRef About the IUS-12
The IUS-12 is a concise self-report measure of intolerance of uncertainty with two factors, Prospective Anxiety and Inhibitory Anxiety. The original development study demonstrated strong internal consistency and a stable two-factor structure across two undergraduate samples. Caution is warranted when applying the instrument to clinical populations because the authors noted that clinical validity and psychometric properties across different languages and populations required further investigation.
References
Carleton, R. N., Norton, P. J., & Asmundson, G. J. G. (2007). Fearing the unknown: A short version of the Intolerance of Uncertainty Scale. Journal of Anxiety Disorders, 21(1), 105–117. https://doi.org/10.1016/j.janxdis.2006.03.014Daouda, C. M., Blanchard, M. A., & Heeren, A. (2023). Is there an all-embracing “intolerance to uncertainty” construct? French Adaptation and Validation of the Intolerance to Uncertainty Scale-Revised. Clinical Neuropsychiatry, 20(1), 48–54. https://doi.org/10.36131/cnfioritieditore20230106Costello, K., Timko, C. A., Anderson, D., & Hormes, J. M. (2025). Validation of the intolerance of uncertainty scale-12 in a sample of pregnant people. BMC Pregnancy and Childbirth, 25(1). https://doi.org/10.1186/s12884-025-07434-1Kusec, A., Murphy, F. C., Peers, P. V., & Manly, T. (2023). Measuring Intolerance of Uncertainty After Acquired Brain Injury: Factor Structure, Reliability, and Validity of the Intolerance of Uncertainty Scale–12. Assessment, 31(4), 794–811. https://doi.org/10.1177/10731911231182693Buhr, K., & Dugas, M. J. (2002). The intolerance of uncertainty scale: psychometric properties of the English version. Behaviour Research and Therapy, 40(8), 931–945. https://doi.org/10.1016/s0005-7967(01)00092-4Carleton, R. N., Teckchandani, T. A., Norton, P. J., & Asmundson, G. J. G. (2026). Still fearing the unknown: Development and initial validation of an ultra-brief intolerance of uncertainty scale. Journal of Anxiety Disorders, 122, 103188. https://doi.org/10.1016/j.janxdis.2026.103188Valencia, P. D., De la Rosa-Gómez, A., Suzán-Montoya, G., Alvarez-López, A., Pérez-Martínez, Z., & Hernández-Posadas, A. (2025). The IUS-4: A Psychometric Evaluation of an Ultra-Brief Intolerance of Uncertainty Measure. Journal of Rational-Emotive & Cognitive-Behavior Therapy, 43(4). https://doi.org/10.1007/s10942-025-00626-w