# The 9 Online Calculators You Need to Know About

When you think of a “calculator”, you probably think of the plastic gadget in your lab desk drawer or an app that came with your phone. But there are so many helpful calculators online that do a lot more than just add and subtract numbers.

Here is a list of some of the wonderfully convenient calculators I’ve found that should get some of those laborious lab calculations done in a jiffy!

## 1. How many days until March 6th?

Date calculator from dateandtime.com

This tool is invaluable. Say you want to inject a mouse every “x” days. Usually, you’d sit down with a calendar and count out each time point. So tedious! With this calculator, all you have to do is type in the start date and then type in +x days and there you have it!

## 2. Working out dilutions?

Solution Dilution Calculator from Sigma-Aldrich.

You type in the stock concentration, the desired volume and the desired concentration and this calculator will give you the required volume.

## 3. Working out the molarity?

Mass Molarity Calculator from Sigma-Aldrich.

The Tocris Molarity Calculator.

Type in the formula weight, the desired volume and the desired concentration and this will give you the mass you should use!

## 4. What is the relative molecular mass?

Molecular Mass Calculator from the Biological Magnetic Resonance Data Bank.

Plug in any chemical formula to this calculator and find out its molecular weight! Be sure to add the brackets.

## 5. The time between dates?

Calculate duration between two dates from dateandtime.com

This one will tell you how many days between two dates!

## 6. Working out your mastermix?

PCR Calculator from Sigma-Aldrich.

There is nothing more aggravating than realizing your calculations are incorrect after you’ve just made up your PCR mastermix. This one is a lifesaver when you’re tired and prone to small mistakes that could ruin your PCR. You give it the numbers, it tells you what to add.

## 7. Diluting a stock volume?

The Tocris Dilution Calculator.

We’ve had enough of C_{1}V_{1} blah blah! This will do it for you!

## 8. Working out the doubling time of your cells?

You supply the initial number of cells, the final number of cells and the culturing time. You can even put in several time points. This tool will graph everything nicely and give you the rate of reproduction of your cells.

## 9. Need a normal calculator?

If you type in “3+7” into google’s search bar (or just type “calculator” into the search bar), it’ll tell you it’s “10”! You can also type in “three plus seven” and get “ten.” You can also get your smart phone to google the answer for you by using the voice search option. You can use it to solve basic arithmetic to more advanced problems, to converting between units and finding out constants. Google has a very helpful guide to some of the shorthand you’ll need to know:

Do you have an online calculator you love? Share it in the comments below!

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Concentrations, volumes, stock solution dilutions, etc. can be calculated with this free online tool: http://www.molbiotools.com/chemicalcalculator.html

DNA and RNA chemical properties, dilutions, absorbances, etc. can be calculated with this free online tool:

http://www.molbiotools.com/dnacalculator.html