Renal & Nephrology Calculators
43 calculators & risk scores
Browse 43 Renal & Nephrology clinical calculators and risk scores used in everyday UK practice. Every tool runs entirely in your browser — enter the values and get instant scoring, colour-coded interpretation bands and a link to the underlying guideline or publication. ClinCalc Pro is free, needs no sign-up, and is built for working clinicians.
These renal & nephrology tools span Renal Function, AKI, Electrolytes, Kidney Function, Fluid / Electrolytes, Acid-Base and more.
- eGFR (CKD-EPI 2021)Estimates GFR using race-free CKD-EPI 2021 creatinine equation. Defines CKD staging.
- Creatinine Clearance (Cockcroft-Gault)Estimates creatinine clearance for weight-based drug dosing (not for CKD staging).
- Fractional Excretion of Sodium (FENa)Distinguishes pre-renal from intrinsic renal AKI using urine and serum sodium and creatinine.
- Fractional Excretion of Urea (FeUrea)Better than FENa for distinguishing pre-renal from intrinsic AKI in patients on diuretics.
- KDIGO AKI StagingStages acute kidney injury by creatinine rise from baseline or urine output criteria.
- Corrected CalciumAdjusts serum calcium for albumin level to obtain true calcium status.
- Anion GapCalculates anion gap to evaluate causes of metabolic acidosis (MUDPILES vs NAGMA).
- MDRD GFR EquationModification of Diet in Renal Disease (MDRD) 4-variable equation for estimating GFR. Largely superseded by CKD-EPI but still widely reported by laboratories.
- Free Water Deficit in HypernatraemiaCalculates the estimated free water deficit in patients with hypernatraemia to guide fluid replacement therapy.
- Sodium Correction for HyperglycaemiaCalculates the corrected (true) serum sodium in hyperglycaemic states (DKA, HHS). Hyperglycaemia causes osmotic dilution of sodium — the corrected value guides fluid resuscitation.
- Serum Osmolality / OsmolarityCalculates estimated serum osmolarity from sodium, glucose, and urea. Compare with measured osmolality to detect an osmol gap (suggesting toxic alcohols or other unmeasured osmoles).
- Urine Anion GapCalculates the urine anion gap (UAG = urine Na⁺ + K⁺ − Cl⁻) to differentiate renal from non-renal causes of normal anion gap (hyperchloraemic) metabolic acidosis.
- Transtubular Potassium Gradient (TTKG)Estimates aldosterone activity by assessing potassium secretion in the collecting duct. Used to differentiate causes of hyperkalaemia (renal vs extra-renal) and hypokalaemia.
- Bicarbonate Deficit CalculatorCalculates the bicarbonate deficit to guide sodium bicarbonate replacement in severe metabolic acidosis.
- Delta Ratio for Mixed Acid-Base DisordersThe delta ratio (delta anion gap / delta bicarbonate) identifies mixed acid-base disorders in the presence of a high anion gap metabolic acidosis. It reveals whether a concurrent metabolic alkalosis or normal anion gap acidosis is also present.
- BUN/Creatinine RatioThe ratio of blood urea nitrogen (urea) to creatinine helps differentiate pre-renal from intrinsic renal causes of acute kidney injury, and can identify upper GI bleeding.
- RIFLE Criteria for Acute Kidney InjuryOriginal AKI staging system (Risk, Injury, Failure, Loss, End-stage) based on creatinine rise, GFR reduction, and urine output. Predecessor to KDIGO AKI staging.
- Sodium Correction Rate in HyponatraemiaCalculates the volume of hypertonic saline (3% NaCl) or normal saline needed to correct hyponatraemia at a safe rate, preventing osmotic demyelination syndrome (ODS).
- Calcium-Phosphate ProductCalculates the calcium-phosphate product to assess risk of metastatic calcification in chronic kidney disease (CKD), particularly vascular and soft tissue calcification.
- Maintenance Fluid Calculator (Holliday-Segar)Calculates maintenance fluid requirements using the Holliday-Segar method: 100 mL/kg for first 10 kg, 50 mL/kg for next 10 kg, 20 mL/kg thereafter. Also provides hourly rate (4-2-1 rule).
- STONE Score for Uncomplicated Ureteral StonesPredicts the likelihood of an uncomplicated ureteral stone on CT-KUB in patients presenting with flank pain. Score 0–13.
- Expected PaCO₂ in Metabolic Acidosis (Winter's Formula)Calculates expected respiratory compensation (PaCO₂) in metabolic acidosis using Winter's formula. Helps identify concurrent respiratory acid-base disorders.
- Urine Protein:Creatinine Ratio (UPCR)Spot urine protein:creatinine ratio estimates 24-hour urinary protein excretion without timed urine collection.
- CKD Staging by eGFR (KDIGO 2012)Classifies CKD stage by eGFR and albuminuria category (G1-G5, A1-A3) per KDIGO 2012 guidelines.
- Potassium Deficit CalculatorEstimates total body potassium deficit in hypokalaemia. Used to guide IV/oral potassium replacement.
- Hyponatraemia Severity & Correction RateClassifies hyponatraemia severity and guides safe correction rate. Maximum correction: 10 mmol/L in 24 hours (6–8 mmol/L in high-risk patients) to prevent osmotic demyelination syndrome (ODS).
- Indications for Renal Replacement Therapy (RRT) in AKIIdentifies absolute and relative indications for initiating RRT (dialysis) in acute kidney injury. Uses AEIOU mnemonic.
- Henderson-Hasselbalch EquationCalculates blood pH from bicarbonate and partial pressure of CO2 (pCO2). Fundamental tool for acid-base interpretation. Complements the stepwise ABG approach.
- AKIN Classification for Acute Kidney InjuryAcute Kidney Injury Network (AKIN) staging for AKI. Modification of RIFLE criteria using serum creatinine and urine output over 48 hours.
- McMahon Score for Acute Kidney Injury from RhabdomyolysisPredicts risk of acute kidney injury requiring RRT in rhabdomyolysis. Score ≥6 = high risk, warrants aggressive IV fluid therapy.
- International IgA Nephropathy Prediction ToolPredicts 50% eGFR decline or end-stage renal disease in IgA nephropathy at 5 and 20 years. Combines clinical and histological (Oxford MEST-C) criteria.
- KDIGO Heat Map for CKD PrognosisKDIGO (Kidney Disease Improving Global Outcomes) prognosis grid for CKD using GFR and albuminuria categories. Identifies low, moderate, high, and very high risk of CKD progression.
- Kt/V for Dialysis AdequacyMeasures adequacy of haemodialysis. Kt/V represents clearance (K) × time (t) / volume of distribution (V). Target: single-pool Kt/V ≥1.4 (KDOQI) or URR ≥65%.
- Kinetic eGFR (KeGFR) in AKIEstimates GFR during acute kidney injury when creatinine is non-steady-state. More accurate than standard eGFR equations during AKI where creatinine is rising or falling.
- CKD Staging (KDIGO 2012)Stages chronic kidney disease (CKD) by GFR category (G1-G5) and albuminuria category (A1-A3) per KDIGO 2012 guidelines.
- AKI Staging (KDIGO 2012)Stages acute kidney injury (AKI) severity using KDIGO 2012 criteria based on creatinine rise and urine output.
- Dialysis Adequacy (Kt/V — Daugirdas)Calculates single-pool Kt/V using the Daugirdas formula to assess adequacy of haemodialysis. Target Kt/V >=1.4 per session (thrice weekly).
- Corrected Calcium (for Albumin)Corrects total serum calcium for hypoalbuminaemia. Ionised calcium is the physiologically active fraction.
- Hyperkalaemia Severity and ECG RiskStratifies hyperkalaemia severity and guides emergency treatment based on potassium level and ECG changes.
- Fractional Excretion of Sodium (FENa)Differentiates pre-renal AKI from intrinsic renal AKI. FENa <1% suggests pre-renal cause; >2% suggests intrinsic renal disease.
- Urine Protein:Creatinine Ratio (UPCR)Estimates 24-hour urinary protein excretion from spot urine protein and creatinine. Used to quantify proteinuria in CKD, nephrotic syndrome, and pre-eclampsia.
- Banff Rejection Classification (Renal Transplant)Classifies renal transplant rejection using Banff criteria from biopsy findings. Guides pulse steroids, antibody-mediated therapy, and transplant team management.
- Furosemide Stress Test (FST) for AKI ProgressionFunctional test predicting progression to severe AKI / RRT (Chawla 2013, ARISE protocol 2020). Single-dose furosemide 1.0 mg/kg (loop-naïve) or 1.5 mg/kg (prior loop) IV; measure 2-hour urine output. Output <200 mL in 2 h indicates non-responsiveness and high risk of progression.