How to use: One Rep Max (1RM) estimates the maximum weight you can lift for one repetition. Enter the weight you lifted in kilograms and the number of repetitions you completed (works best with 1-10 reps). Uses Brzycki formula for accurate estimation. Shows your estimated 1RM and training percentages: 90% for strength (1-3 reps), 85% for power (3-5 reps), 80% for hypertrophy (6-8 reps). Never attempt true 1RM without proper warm-up and spotters. Use these estimates to program training loads safely. Essential for powerlifting, bodybuilding, and strength programming.

How to use: GFR (Glomerular Filtration Rate) measures kidney function - how well kidneys filter waste from blood. You need a blood test result for serum creatinine (in mg/dL) from your doctor. Enter the creatinine level, your age, gender, and race (African American or Other). Uses MDRD equation to calculate eGFR. Normal GFR: >90. Stages: G1 (≥90, normal), G2 (60-89, mildly decreased), G3 (30-59, moderate decrease), G4 (15-29, severe decrease), G5 (<15, kidney failure). This is a screening tool - always discuss results with your healthcare provider for proper interpretation and treatment.

How to use: Body Surface Area (BSA) calculates total skin surface area in square meters, used primarily for medical dosing calculations. Enter your height in centimeters and weight in kilograms. Choose between DuBois Formula (most common, from 1916) or Mosteller Formula (simpler, from 1987). Average adult BSA is 1.7-2.0 m². Healthcare providers use BSA to calculate proper medication doses, especially chemotherapy, burn treatment fluid requirements, and cardiac output. This ensures doses are scaled to body size for safety and effectiveness. Not needed for general health tracking.