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The best free Medical Calculator apps for the iPhone

Medical Calculators are some of the most essential apps to have for your iPhone when in the hospital or clinic setting.  There are a litany of quality medical calculators in the App Store, and some are costly, but there are plenty of free — or almost free — medical calculators that are on par with the more expensive medical calculators in the App Store.

In this review we’ll look at four medical calculator apps and see how they stack up against one another — Epocrates’s MedMath, MedCalc, QxMD Calculate, and Skyscape’s Archimedes.  Three of these medical calculators are free, and one, MedCalc, is $0.99 [recently MedCalc went from free to being a paid app].  

Epocrates MedMath

First, we take a look at Epocrates MedMath, which comes included in the free version of Epocrates (We reviewed Epocrates Rx on iMedicalApps in February 2010). MedMath contains approximately 45 clinical calculators ranging from the useful almost-every-day-on-the-wards (corrected serum calcium calculator, FeNa calculator, GFR calculator) to the rarely-used for medicine residents (transtubular K gradient, Daugirdas for hemodialysis, pregnancy wheel). These various calculators are alphabetically organized and can be browsed by category, but cannot be searched for.

“Preferences” allows for customizing the MedMath display by name/category or even a list of favorites, and flipping between US vs SI units for height and weight.

For the purposes of this comparison article, we will focus on a clinical calculator common to all three apps that many physicians and medical students are forced to use often— a creatinine clearance calculator (for this comparison, we will use each app’s version of the Cockroft-Gault equation).

One nice touch of MedMath is the “Info” button in the top-right corner of each clinical calculator, which displays the actual formula used in the calculator as well as any historical or teaching notes (here, why it matters whether the patient is male or female for the purposes of calculating creatinine clearance, and the reference in which the particular formula or equation was first established (here, the original Cockroft & Gault paper published in Nephron in 1976).

As you can see, MedMath’s navigation is simple and its user interface clear.  Units can be easily switched from within any calculator, and often-used calculators can be designated as “favorites.”  However, MedMath features only ~45 clinical calculators, and these cannot be searched for in any way other than alphabetically or by category, making them occasionally difficult to locate.


Next, we survey the MedCalc app from two Swiss physicians (Drs. Pfiffner and Tschopp), which we have reviewed in full on iMedicalApps in both its basic and paid Pro versions.

The basic MedCalc app is 99 cents, though its Pro version, which does not add much more beyond the “patient management system” (which allows for saving of data for individual patients) and one-line captions for each formula while navigating, costs $4.99.  In comparison to MedMath’s ~45 clinical calculators, MedCalc offers users approximately 150 different calculators, formulas, or scales/scores—a three-fold increase.

As its home screen shows, MedCalc’s calculators can be searched by text/keyword (here, searching its various formulas for “deficit”), a useful feature not found in MedMath.

As for MedCalc’s Cockroft-Gault creatinine clearance calculator, note how units can be changed from the right side of the keyboard.

The info button in the top-right corner (available both in the free and Pro versions of MedCalc) displays the appropriate formula with units, proper clinical use, and the appropriate reference (here, the original Cockroft & Gault Nephron paper) with an active PubMed link.

Other nice features of MedCalc include out-of-range or hard-to-believe values showing up in a red font (shown below, as if a user accidentally added an extra zero to a patient’s weight when calculating their creatinine clearance) and the ability to shake one’s device to reset all fields within a calculator.

MedCalc also offers the ability to star formulas and store them in the “Favorites” tab.  Straightforward navigation and handy features like these make MedCalc easy to use and master.