Background: Celiac disease prevalence approaches 1%; more suffer from non-celiac gluten sensitivity. Aims: Our goal was to estimate the prevalence of gluten intolerance. Methods: We invited US adults (18–80 years) via Amazon's mechanical Turk to complete an online survey. Gluten intolerance was defined as self-reported intolerance to wheat, barley, rye, flour, or pasta. Those with celiac disease were not excluded. Results: We collected 2133 responses. Rate of gluten intolerance was 5.1% (95% CI 4.2–6.1%). Each food had different rates: wheat 4.8%, flour 1.2%, pasta 0.9%, barley 0.8%, and rye 0.8%. Among 108 adults reporting any gluten intolerance, 62.0% selected only wheat, 10.2% selected all gluten-containing grains excluding pasta and flour, and 5.6% selected all gluten-containing products. Overall intolerance to any food was 24.8% (95% CI 23.0–26.6%). Wheat was second only to lactose. Conclusions: Self-reported intolerance to wheat, but not all gluten-containing foods, is common. Findings may suggest poor knowledge of gluten-containing foods or that self-perceived non-celiac gluten sensitivity is prevalent. [ABSTRACT FROM AUTHOR]