Arithmetic only

Calculators

Use fictional numbers. Each tool shows its equation and units — these are for learning and discussion, never orders.

Predicted body weight & tidal volume

Height Unit Equation coefficientThe source equations use sex-specific constants. Weight for BMI (kg, optional)

Equations & limits

PBW (ARDSNet): 50 (male) or 45.5 (female) + 0.91 × (height cm − 152.4) kg. Tidal-volume examples = PBW × 6 and × 8 mL/kg.

Devine IBW: 50 or 45.5 + 2.3 × (height in − 60) kg; shown for heights ≥ 60 in. Not a healthy-weight target and not a dosing weight by itself.

BMI: kg ÷ m². 1 in = 2.54 cm. The 120–230 cm limit is a software guardrail, not evidence of formula validity.

Percent → mg/mL

Solution strength (%)

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Rule: % × 10 = mg/mL (1% = 1 g/100 mL = 10 mg/mL)

Dose → volume

Fictional values only.

Dose Unit Concentration (per mL) Unit

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volume = dose ÷ concentration

Maximum allowable blood loss

Weight (kg) EBV (mL/kg) Starting Hct (%) Lowest acceptable Hct (%)

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EBV × (Hct₀ − Hct₁) / Hct₀ — a teaching estimate

Age-adjusted MAC

Agent Age (years)

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MAC₄₀ × 10^{−0.00269 × (age − 40)} (Mapleson 1996)

Sources: ARDS Network, NEJM 2000 (PBW); Devine 1974 via Peterson et al. 2016 (IBW); CDC (BMI); Mapleson 1996 (MAC). Fixtures tested in tests/calc.test.mjs.