Description： The internet ranks happiness by IQ, but studies find a small link. Chainsaw Man's Denji helps explain why enjoying breakfast is not the same as being satisfied with life.
IQ does not determine your happiness grade. A synthesis of research found only a small relationship between general intelligence and life satisfaction.[1] Yet a viral graphic awards people below IQ 70 a cheerful B+, calls those between 110 and 125 “S+++”, then downgrades 125–135 to a lonely “F--”. Gain ten IQ points and your entire life apparently receives a disastrous software update.
It also brings to mind Denji from Chainsaw Man, whose delight in an ordinary breakfast seems almost boundless. Is that really because he is supposedly less intelligent?
1. The percentages fail a reality check
The graphic claims 7.1% score below IQ 70 and 2.5% score at least 135. On a conventional IQ scale with mean 100 and standard deviation 15, a normal-distribution calculation yields roughly 2.3% and 1.0%. For IQ 95–110, the theoretical share is 37.8%, not the image's 31.5%.
These are mathematical benchmarks, not actual measurements of a given country. A special sample might differ. But the graphic names no population, test, questionnaire or source. Decimal points are not references.
2. Research finds a small association
A 2017 meta-analysis found correlations of 0.11 between general intelligence and life satisfaction, and 0.05 with job satisfaction.[1] Both are small and positive. Squaring 0.11 gives about 1.2%, a rough measure of shared variation in a simple two-variable comparison, not a personal prediction.
A British survey analysis of 6,870 adults found lower reported happiness in a lower-IQ group; income, health and difficulty with everyday activities accounted for much of the association.[2] A 2024 study also found results shift depending on how happiness and education are measured.[3] A six-grade destiny chart is a poor substitute for this complexity.
3. A happy moment is not a happy whole life
The OECD's 2025 guidance distinguishes overall life evaluation, day-to-day feelings, and a sense of meaning or purpose.[4] You can love breakfast and still be anxious about debt. You can be satisfied with your life and have a terrible Tuesday. Treating little pleasures and life satisfaction as interchangeable is like asking a thermometer to calculate your rent.
4. Denji's toast is about what he lacked
The official Chainsaw Man introduction describes Denji and Pochita hunting devils to repay inherited debt while living in severe poverty.[5] Jam on toast represents access to an ordinary comfort that once felt unreachable. A small pleasure can feel huge because of the life that preceded it.
That is an interpretation of the story, not an IQ test of Denji. He also keeps facing new desires and painful relationships after enjoying a meal. Being thrilled by toast is not the same as living happily ever after.
5. Is high intelligence a sentence to loneliness?
Some people feel misunderstood. But a 2011 study comparing 101 intellectually gifted adults with 91 comparison participants found no statistically significant differences in the dimensions of subjective well-being measured.[6] Friends also depend on trust, shared interests and circumstances. An IQ score does not come with a social compatibility certificate.
6. The ranking misses the point
Intellectual ability, enjoying the present and evaluating an entire life are different questions. Research reveals average patterns, not the happiness report card of any one person.
Denji dreamed of ordinary living, not getting a perfect test score. If IQ determined the taste of jam toast, every bakery would have an intelligence-testing booth next door. Let him enjoy breakfast.
References (6)
- Gonzalez-Mulé, Carter & Mount (2017), Are smarter people happier? doi.org
- Ali et al. (2012/2013), IQ and happiness: England survey of 6,870 adults pubmed.ncbi.nlm.nih.gov
- Intelligence, educational attainment, and wellbeing (2024) doi.org
- OECD Guidelines on Measuring Subjective Well-being (2025 Update) doi.org
- Chainsaw Man anime, official story introduction chainsawman.dog
- Wirthwein & Rost (2011), Giftedness and subjective well-being doi.org
