Kidney Stone Risk Calculator
Assess your risk of developing kidney stones based on diet, hydration, BMI, family history, and medical history.
Kidney Stone Risk
What Are Kidney Stones? Kidney stones (nephrolithiasis) are hard mineral deposits that form inside the kidneys when urine contains more crystal-forming substances — like calcium, oxalate, and uric acid — than the fluid can dilute. They range from tiny specks to stones large enough to block urine flow, causing severe flank pain (renal colic), nausea, and blood in the urine.
About 1 in 10 people will develop a kidney stone during their lifetime. Men are more affected than women, though women’s rates have been rising.
Types of Kidney Stones
- Calcium oxalate (most common — ~80%) — forms when calcium combines with oxalate in urine
- Uric acid — from high-protein diets or gout; more common in men
- Struvite — associated with urinary tract infections
- Cystine — rare; caused by a genetic disorder
Key Risk Factors
- Low fluid intake — the single most modifiable risk factor. Concentrated urine creates the perfect environment for stone formation. Aim for 2–3 liters of water daily (about 8–12 glasses).
- High sodium diet — increases calcium in urine by reducing kidney reabsorption
- High animal protein diet — increases uric acid and reduces citrate (a natural stone inhibitor)
- Obesity (high BMI) — associated with more acidic urine and higher uric acid levels
- Prior kidney stones — 50% chance of recurrence within 5 years without preventive measures
- Family history — genetic factors account for a significant portion of risk
- Hot, dry climate — increases sweating and reduces urine output
Prevention Strategies
- Drink enough water to produce at least 2 liters of urine daily (urine should be pale yellow)
- Reduce sodium to under 2,300 mg/day
- Limit animal protein — moderate portions of meat, poultry, fish, and eggs
- Eat calcium-rich foods (do not avoid calcium — dietary calcium actually binds oxalate in the gut)
- Avoid high-oxalate foods if you have calcium oxalate stones (spinach, nuts, chocolate)
- Maintain a healthy weight through diet and exercise
- Speak to your doctor about potassium citrate supplementation if you have recurrent stones