Utilities
Browser-based tools for health metrics, experiment stats, business quick math, and personal finance. None of this is medical, legal, or financial advice; use for learning and rough checks only.
Screening-style estimates and planners. Always confirm with a clinician for care decisions.
Body mass index from metric or imperial units with standard adult categories.
Open →Mifflin–St Jeor estimate of maintenance calories and optional daily deficit target.
Open →Protein by body weight plus carb/fat split of remaining calories.
Open →Plan eating window from a last-meal time and fasting hours (e.g. 16:8).
Open →Rough daily fluid target from weight and activity level.
Open →Simplified point models for diabetes and heart risk (not a diagnosis).
Open →Reference checklist by age group; track last doses you enter.
Open →Very rough lifestyle-adjusted estimate from a simple baseline (illustrative only).
Open →Classical formulas for experiments and summaries. Assumptions matter; validate for production work.
Two-proportion z-test: lift, z-score, and two-sided p-value.
Open →Per-group n for comparing two proportions at 80% or 90% power (normal approximation).
Open →95% CI for a mean (z) or proportion (Wikipedia Wilson interval).
Open →Describe strength of Pearson r with rule-of-thumb bands.
Open →Standardized mean difference with pooled SD and small/medium/large labels.
Open →Back-of-envelope models for prioritization and economics.
Return on investment from gain and cost.
Open →Net present value from yearly benefits, costs, discount rate, and horizon.
Open →Units to cover fixed costs given price and variable cost per unit.
Open →Chain multipliers to go from population or accounts to opportunity slices.
Open →Score initiatives on impact vs. effort and sort into quadrants.
Open →Salary and debt intuition tools. Indices are user-supplied for cost-of-living comparisons.
All calculators are provided as-is for education. Health tools are not diagnostic. Statistical tests assume idealized conditions. Business and finance outputs omit taxes, fees, and many real-world frictions unless noted. Verify important decisions with qualified professionals.
