The CanUFight algorithm begins from a neutral 50% baseline, representing the global median adult’s likelihood of winning a fair, one-on-one, unarmed fight. Each user input modifies that baseline through weighted multipliers informed by real-world data and combat principles.
Sex selection applies a small multiplier to your base score:
Male: x 1.1
Female: x 0.9
Scientific data consistently shows measurable physiological differences between males and females that impact combat performance, primarily in strength, power, and endurance.
Males possess 50-60% greater upper and lower body strength due to lean mass vs fat mass disparities, even when matched for height and weight. Female athletes have 5-10% more body fat than similarly trained males and 85% the lean body mass.
Males exhibit larger proportions of Type II (fast-twitch) muscle fibers and greater tendon stiffness, both linked to superior explosiveness and force transmission.
Average VO₂max and hemoglobin levels are 10-20% higher in males, enhancing recovery and sustained output during exertion.
These combined advantages translate to a modest but consistent edge in physical exchanges, even when other attributes are equal. To represent this gap, the multipliers that were chosen correspond to roughly a 55-45 performance advantage for males under otherwise identical conditions. This is large enough to reflect biological reality, but not so large that it overshadows training and athleticism.
Sources considered:
https://pubmed.ncbi.nlm.nih.gov/39501696/
https://pmc.ncbi.nlm.nih.gov/articles/PMC7930971/
https://pubmed.ncbi.nlm.nih.gov/37424380/
https://pubmed.ncbi.nlm.nih.gov/40657230/
https://epublications.marquette.edu/cgi/viewcontent.cgi?article=1223&context=exsci_fac
Human physical performance changes predictably over the lifespan due to growth, hormonal development, and age-related muscular decline. The multiplier system reflects these well documented physiological trends, using distinct phases calibrated from exercise-science research.
Childhood (0-12 years):
Children have limited muscle mass, neuromuscular coordination, and power output. This age range begins near zero fighting capability, and slowly rises to about 40% of adult capacity by age 12.
Adolescence (13-17 years):
Puberty triggers large increases in testosterone, muscle cross-sectional area, and anaerobic power. Strength and sprint performance increases rapidly through this age range, approaching adult values by 17-18 years. The model therefore ramps linearly from 40% to full adult strength during this period.
Prime Adulthood (18-35 years):
Peak muscle mass, reaction speed, and aerobic capacity occur in adulthood. This range is treated as the neutral bseline with a multiplier of x 1.
Post-Prime Decline (36+ years):
Skeletal muscle and pwoer output gradually declines due to sarcopenia and reduced fast-twitch fiber area. Longitudinal studies estimate a ~1-2% loss of muscle strength per year after the mid-30's. To capture this, the model applies an exponential decay of roughly 1.5% per year beyond age 35.
Sources considered:
https://www.health.harvard.edu/exercise-and-fitness/age-and-muscle-loss
https://pmc.ncbi.nlm.nih.gov/articles/PMC2804956/?
https://ourworldindata.org/grapher/population-by-five-year-age-group
Height indirecty affects fighting performance through reach advantage, which is highly correlated with height (wingspan ≈ height in most adults). While height alone does not determine outcomes, a longer reach allows a fighter to strike or control distance more effictively.
An analysis by Bruins Sports Analytics of over 6,000 UFC fights from 1993 to 2021 found that fighters with a reach advantage won more often on average. Full results:
1+ inch reach advantage = 52.28% win rate (+2.28 from base)
2+ inch reach advantage = 53.79% win rate (+1.51 from previous)
3+ inch reach advantage = 54.88% win rate (+1.09 from previous)
4+ inch reach advantage = 55.27% win rate (+0.39 from previous)
5+ inch reach advantage = 56.13% win rate (+0.86 from previous)
6+ inch reach advantage = 58.82% win rate (+2.69 from previous)
7+ inch reach advantage = 62.39% win rate (+3.57 from previous)
The average increase in win rate across inches 1 through 7 = +1.68%
To model this, height is converted to a smooth multiplier centered on the global average of 65 inches (5'5"). Each inch above average increases the multiplier by 1.68%, tapering off after 7 inches. Each inch below average decreases it symmetrically. The result produces a realistic ±15% range overall, reflecting the modest but measurable advantage of reach.
Sources considered:
https://www.kaggle.com/datasets/rajeevw/ufcdata
https://www.bruinsportsanalytics.com/post/mma_reach
https://ourworldindata.org/human-height