Let’s start with the Adrogué–Madias (A-M) formula (1997): Na+ deficit = TBW fraction x weight x ΔNa+
Sodium Deficit Calculator
Estimate the sodium amount represented by a planned serum sodium increase.
Version 1.0.0
Sex
coefficient
Sodium deficit
—
mmol
No clinical values are intentionally saved by this control.
Equations
Sodium deficit
Sodium deficit (mmol) = sex coefficient × weight (kg) × (target sodium − starting sodium) (mmol/L)The coefficient is 0.6 for male and 0.5 for female. The displayed result is rounded to the nearest whole mmol.
References
- Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581-1589. PMID: 10824078 DOI: 10.1056/NEJM200005253422107
- Nguyen MK, Kurtz I. A new quantitative approach to the treatment of the dysnatremias. Clin Exp Nephrol. 2003;7(2):125-137. PMID: 14586731 DOI: 10.1007/s10157-003-0233-3
Glucose-corrected Sodium Calculator
Estimate sodium concentration after correction for hyperglycaemia
Version 1.0.0
Glucose units
Corrected sodium
— mmol/L
This estimate preserves the source calculator's correction factor. It supports clinical assessment but does not prescribe a sodium or glucose treatment target.
No clinical values are intentionally saved by this control.
Equations
Glucose-corrected sodium
Corrected Na⁺ (mmol/L) = measured Na⁺ (mmol/L) + [glucose (mmol/L) − 5] ÷ 3The final result is rounded to the nearest whole mmol/L, matching the frozen source calculator. This source-specific correction is equivalent to adding approximately 1.85 mmol/L sodium for each 100 mg/dL glucose above 90 mg/dL.
Glucose unit conversion
Glucose (mmol/L) = glucose (mg/dL) ÷ 18The calculator converts mg/dL input to mmol/L before applying the correction equation.
References
- Katz MA. Hyperglycemia-induced hyponatremia--calculation of expected serum sodium depression. N Engl J Med. 1973;289(16):843-844. PMID: 4763428 DOI: 10.1056/NEJM197310182891607
- Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999;106(4):399-403. PMID: 10225241 DOI: 10.1016/S0002-9343(99)00055-8
Sodium Chloride Solution Concentration
Convert sodium chloride percentage strength to sodium concentration
Version 1.0.0
Sodium concentration (Na⁺)
—
mmol/L
Sodium chloride concentration
—
g/L
Assumes the labelled percentage is sodium chloride weight/volume and complete dissociation, so each millimole of NaCl supplies one millimole of Na⁺. Verify the product label before clinical use.
No clinical values are intentionally saved by this control.
Equations
Percentage weight/volume to mass concentration
NaCl (g/L) = NaCl (% w/v) × 10A percentage weight/volume solution contains that number of grams of sodium chloride in 100 mL of solution.
Sodium concentration
Na⁺ (mmol/L) = [NaCl (g/L) ÷ 58.5 g/mol] × 1000 mmol/molAssumes complete dissociation of sodium chloride and a 1:1 molar ratio of NaCl to Na⁺. The displayed result is rounded to the nearest whole mmol/L.
References
- Bureau International des Poids et Mesures. The International System of Units (SI). 9th ed. Sèvres: BIPM; 2019.
- National Center for Biotechnology Information. PubChem Compound Summary for CID 5234, Sodium Chloride. Bethesda (MD): National Library of Medicine; 2026. Molecular weight 58.44 g/mol and formula NaCl (1:1 sodium-to-chloride stoichiometry).
- National Library of Medicine (US). DailyMed: Sodium Chloride Injection, USP [drug label]. Bethesda (MD): National Library of Medicine; updated 2026 May 19. 0.9% solution contains 900 mg NaCl per 100 mL and 154 mEq/L each of sodium and chloride.
How to make 3% Saline
This is an ADDITIVE calculator. That means that you start with a volume of 0.9% saline, and you add 23.4% saline to it, giving you the final 3% solution. That’s it. There is no removing fluid at any point. simply add one to the other.
Start with 100 mL of 0.9% saline
ADD 10 mL of 23.4% saline
Result: 110 mL of 2.9% saline