Free tools
28 calculators and tools, free and without an account. Every clinical formula shows the equation it evaluated, the paper it came from, when it was last checked, and what it does not account for — so you can verify it rather than trust it.
They all run in your browser. Nothing you type is sent to VitalFax or stored anywhere.
Clinical calculators
Published formulas, each showing the equation it evaluated and the source it follows.
Adjusted body weight calculator
Adjusted body weight for dosing in obesity, from ideal and actual weight.
Widely used dosing convention; the 0.4 factor varies by agent
Anion gap calculator
Serum anion gap with the albumin correction, which is omitted more often than not.
Figge J et al.
BMI calculator
Body mass index from height and weight, with the WHO adult category.
World Health Organization — Body mass index classification
Body surface area calculator
Body surface area by the Mosteller, Du Bois and Haycock formulas.
Mosteller RD
Corrected calcium calculator
Albumin-corrected serum calcium, with the ionised-calcium caveat stated plainly.
Payne RB et al.
Creatinine clearance calculator (Cockcroft-Gault)
Estimated creatinine clearance by Cockcroft-Gault, the basis of most renal dosing.
Cockcroft DW & Gault MH
eGFR calculator (CKD-EPI 2021)
Estimated GFR by the race-free CKD-EPI 2021 creatinine equation, with CKD stage.
Inker LA et al.
Ideal body weight calculator
Ideal body weight by the Devine formula, with the Robinson and Miller variants.
Devine BJ
Mean arterial pressure calculator
Mean arterial pressure from a systolic and diastolic reading.
Standard haemodynamic approximation
Morphine milligram equivalent (MME) calculator
Total daily MME across oral opioid prescriptions, for cumulative dose assessment only — not for switching opioids.
CDC Clinical Practice Guideline for Prescribing Opioids for Pain — conversion factors for cumulative dose assessment
Pregnancy due date calculator
Estimated due date and current gestational age from the last menstrual period.
Naegele’s rule; ACOG Committee Opinion 700 on estimating due date
QTc calculator
Rate-corrected QT interval by Bazett, Fridericia, Framingham and Hodges.
Bazett (1920)
Clinical scores
Validated risk and severity scores. Each states what it was derived to predict and in which population.
Centor and McIsaac score calculator
Likelihood of group A streptococcal pharyngitis, with the McIsaac age adjustment.
Centor RM et al. (1981); McIsaac WJ et al.
CHA₂DS₂-VASc calculator
Stroke risk in non-valvular atrial fibrillation, with annual risk by score.
Lip GYH et al.
CURB-65 calculator
Severity of community-acquired pneumonia, with 30-day mortality by score.
Lim WS et al.
Glasgow Coma Scale calculator
Glasgow Coma Scale total with the eye, verbal and motor breakdown.
Teasdale G & Jennett B
HAS-BLED calculator
Major bleeding risk on anticoagulation for atrial fibrillation.
Pisters R et al.
HEART score calculator
Six-week major adverse cardiac event risk in undifferentiated chest pain.
Six AJ
Wells score calculator for DVT
Pre-test probability of deep vein thrombosis by the Wells criteria.
Wells PS et al.
Wells score calculator for pulmonary embolism
Pre-test probability of pulmonary embolism, in both the three-tier and two-tier forms.
Wells PS et al.
Unit conversion
Exact conversions between the units used in clinical and laboratory practice.
Laboratory unit converter
Converts between conventional and SI units for twelve common analytes.
Conversion factors derived from analyte molar mass
Weight, height and temperature converter
Exact conversions between pounds and kilograms, inches and centimetres, °F and °C.
International yard and pound agreement (1959); SI definitions
Fax tools
Working out what fax costs, and producing the paperwork that goes with it.
Fax cost calculator
What a fax line really costs per year, counting the line, the hardware, the consumables and the staff time.
Fax line capacity calculator
Whether your fax lines can carry your busiest hour, or whether senders are getting a busy signal.
Fax page volume estimator
Estimates monthly fax pages from how your practice actually works, for plan sizing.
Fax staff time calculator
How many staff hours a week go into sending, receiving and filing faxes, and what that time costs.
Toll-free vs local fax number comparison
What a toll-free fax number costs against a local one at your volume, using the rates you are actually quoted.
Document tools
Everyday document work, performed in your browser.