This calculator applies published equations to adult height and weight. It is useful for understanding a model and its arithmetic, but cannot determine actual blood volume, diagnose blood loss, or select a treatment.
Two models, not a certainty range
Nadler is always the primary estimate. Lemmens is an optional BMI-based comparison developed in the context of obesity. A difference between their results reflects different model assumptions; it is not a confidence interval or proof that either result is correct. No BMI cutoff automatically selects a preferred method.
Who is outside the intended scope?
Do not apply these results to children or pregnancy. Hydration changes, acute bleeding, edema, heart or kidney disease, critical illness, unusual body composition and extreme size can make a population estimate unreliable. A mathematically accepted input is not evidence of clinical validity. The published coefficient choices are limited and do not establish an individualized choice for transgender or intersex people or people receiving hormone therapy.
Hematocrit and privacy
The optional component breakdown uses the Nadler total, not Lemmens. Peripheral hematocrit does not exactly equal whole-body hematocrit, so multiplying by a percentage is only an educational approximation. Local saving is opt-in; a shared link deliberately contains inputs and may be visible to its recipients and in browser history.
Related learning
The plasma volume calculator explores a related estimate, while the body surface area calculator uses height and weight for a different purpose. Neither validates this result or determines safe blood donation, blood loss or transfusion.