Calculators from the Ark to the iPhone

I have an old calculator. So old that people laugh when they see it and then politely change the subject. Now I hide it like a guilty secret if I am using it and I see someone coming. I keep it in my desk drawer and only sneak it out to do quick simple arithmetic that I am too lazy to do by hand. Despite the shame, I will probably keep it forever. I cannot abandon it just because it is now old and extremely unfashionable. It was useful! It served me well throughout my undergraduate and graduate studies when I actually used the vast array of statistical functions it offers. I also used it a lot in the lab to do the many routine, small calculations required from day to day.

We have spent the last couple of months working on a calculator function for the Promega iPhone™ App. The contrast between the iPhone and my dusty old calculator is stark. The old one is a good general workhorse, the new one is a precision tool. The iPhone App calculator features the following molecular biology calculations:iPhone Tm Calculator Screen

Tm calculator


Solution Molarity

Degrees Celsius to Fahrenheit to Kelvin

Micrograms to picomoles

Micrograms of linear DNA to picomoles of DNA ends

Molar ratio of insert to vector DNA

Absorbance at 260nm to amount of DNA, RNA, or oligo

Protein size and amount to picomoles

Coding capacity of DNA

We hope that iPhone users will find the iPhone App calculators handy and easy to use. Hopefully they will take the pain out of some of the routine calculations scientists have to perform frequently in the course of their work. The same calculators are also available on the Promega web site, so if you don’t have an iPhone, you can access them at

You can download the Promega App on the App Store. Try it out and see if it stands the test of time.

iPhone is a trademark of Apple, Inc.

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Isobel Maciver

Isobel Maciver

Isobel is a graduate of the University of Edinburgh and of Aston University in Birmingham, U.K. She is a technical writer and editor, and is also manager of the Scientific Communications group at Promega. She enjoys writing about issues in science and communication.

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