Chronological age counts birthdays. Biological age measures how your body is actually holding up, and the two can differ by more than a decade in either direction. This calculator uses PhenoAge, a published algorithm developed by Morgan Levine and colleagues, which predicts mortality risk more accurately than age alone using nine markers from routine blood work.
Enter your age and all nine blood markers to compute your biological age. Every marker is required, the algorithm weighs them together.
PhenoAge was built by finding which routinely measured blood markers best predicted mortality across large population datasets. Nine survived the analysis: albumin, creatinine, glucose, C-reactive protein, lymphocyte percentage, mean cell volume, red cell distribution width, alkaline phosphatase and white blood cell count. Combined with chronological age and weighted by the published coefficients, they produce an age in years.
This calculator implements the original equation along with the 2019 published correction that fixed an error in the paper's stated formula. That correction matters, and several calculators online still use the broken version.
A number on its own is a novelty. What makes it useful is knowing which markers are responsible. This tool recalculates your biological age nine times, each time replacing one marker with an optimal value, and measures how many years that marker alone is costing you.
The result is a ranked list. If inflammation is adding six years and glucose is adding four, you know exactly where to work, and you can retest in a few months to see whether it moved. Cross-check the same panel against the Bloodwork Analyzer for a fuller read across all eight physiological systems, not just mortality risk.
Creatinine is one of the nine inputs and it rises with muscle mass. A lean, muscular person can read biologically older purely because they carry more muscle, which is the opposite of what the marker is meant to indicate. The tool flags this so you can weigh the result properly. Cystatin C is a muscle independent alternative worth asking your doctor about.
PhenoAge is built from blood chemistry. It knows nothing about your cardiorespiratory fitness, strength, body composition, sleep or muscle mass, all of which matter enormously for healthspan. Treat it as one informative lens, not a verdict. The Calorie & TDEE Calculator and your training log cover the ground this tool cannot.
A comprehensive metabolic panel covers albumin, glucose, creatinine and alkaline phosphatase. A complete blood count with differential covers white blood cells, mean cell volume, red cell distribution width and lymphocyte percentage. High sensitivity CRP is usually ordered separately. Fast before the glucose draw.
PhenoAge outperformed chronological age at predicting mortality across large validation cohorts, which is a strong result for a nine marker model. It is a population level statistical association, so it describes risk rather than destiny, and it cannot account for individual circumstances.
Work on the markers the tool identifies as costing you the most years. Inflammation, fasting glucose and white blood cell count respond to body composition, training, sleep and diet within weeks to months. Red cell distribution width and mean cell volume often reflect iron, B12 or folate status, and alcohol intake.
Every three to six months is reasonable. Some markers, particularly CRP and glucose, can shift within weeks of a genuine change in habits, while others move slowly. Testing more often than that mostly measures noise.
Usually one or two markers are driving it rather than everything being slightly off, which is why the breakdown matters. Inflammation and metabolic markers are the most common culprits. If creatinine is the main contributor and you carry significant muscle, the result likely overstates the situation.
