OsmoCalc Electrolyte Conversion Reference

For Estimating Osmolality in Liquid Feeds

This table summarizes common electrolyte ingredients, how they are reported on product labels, and how they contribute to osmolality once dissolved.

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Common Electrolyte Ingredients

Ingredient	Chemical Formula	Molecular Weight (g/mol)	Dissociation in Solution	Approx. mOsm per gram
Sodium chloride	NaCl	58.5	Na⁺ + Cl⁻	~34
Sodium bicarbonate	NaHCO₃	84.0	Na⁺ + HCO₃⁻	~24
Sodium acetate	NaC₂H₃O₂	82.0	Na⁺ + Acetate⁻	~24
Sodium propionate	NaC₃H₅O₂	96.0	Na⁺ + Propionate⁻	~21
Sodium citrate	Na₃C₆H₅O₇	258.0	3 Na⁺ + Citrate³⁻	~31
Glycine	C₂H₅NO₂	75.0	Does not dissociate	~13

Values are approximate and intended for practical estimation.

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Mass-Based Conversions

Quantity Reported	Conversion
1 g compound	= 1000 mg
1 g compound	= (1000 ÷ molecular weight) mM
mM × number of particles	≈ mOsm

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Millimoles (mM) and Milliequivalents (mEq)

Ion Type	Charge	Relationship
Monovalent (Na⁺, Cl⁻, HCO₃⁻, acetate⁻)	±1	1 mEq = 1 mM
Divalent (Ca²⁺, Mg²⁺)	±2	1 mEq = 0.5 mM
Trivalent (citrate³⁻)	±3	1 mEq = 0.33 mM

Note:
mEq accounts for electrical charge; osmolality depends on particle number, so OsmoCalc converts mEq to mM internally.

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How OsmoCalc Uses These Values

• Osmolality is calculated based on osmotically active particles, not ingredient names
• Compounds dissociate into ions that each contribute to osmolality
• OsmoCalc allows entry of percent acetate, propionate, bicarbonate, citrate, and glycine to standardize calculations across different label formats

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Practical Guidance

• Use grams when that is what the label provides
• Use mM directly if listed
• Convert mEq to mM using ion charge
• Enter ionic percentages when available — this is the most consistent approach

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Quick Take-Home

Different labels describe the same chemistry. OsmoCalc converts everything to particle counts so users don’t have to.