Low-FODMAP Portion Calculator
Check whether a serving of a common food stays within its low-FODMAP threshold, and see how many safe servings your portion is worth.
How it works
Servings = portion ÷ safe serving size · Within limit when portion ≤ safe serving
FODMAPs are fermentable carbohydrates that can trigger IBS symptoms, and crucially the dose matters: many foods are low-FODMAP in a small serving but high-FODMAP once you eat more. Monash University tests these thresholds and publishes green-light serving sizes. This tool compares your portion to the safe serving for a food, so you can enjoy it in a tolerated amount rather than avoiding it entirely.
Worked example
Canned chickpeas are low-FODMAP up to 42 g (about ¼ cup, rinsed). A 45 g portion is 1.07 safe servings — just 3 g over the threshold, so scaling back slightly keeps it in the green range.
Frequently asked questions
Why do serving sizes matter so much on low-FODMAP?
FODMAP effects are dose-dependent. A food can be perfectly tolerated in a small serving and cause symptoms in a larger one, which is why Monash publishes specific gram thresholds rather than simple allowed/avoid lists.
Does rinsing canned legumes help?
Yes. Canned chickpeas and beans that are drained and well rinsed have a lower FODMAP load than dried-and-boiled versions, because some of the fermentable carbohydrates leach into the liquid.
Is low-FODMAP meant to be permanent?
No. It is a short elimination phase followed by structured reintroduction to identify your personal triggers and tolerances. The goal is the least restrictive diet that keeps you symptom-free.
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Educational estimate for meal planning, not medical or nutrition advice. Serving thresholds and needs vary by person — check with a dietitian for medical diets.