Radiochemicals calculators

Amersham Biosciences has designed seven calculators to help you with the most common radioactive decay and chemical concentration calculations - calculations which occur in everyday radiochemical usage.

The Unit Conversion Calculator (Becquerel/Curie Conversion Calculator) can be used to perform conversions between the two unit types, converting both from curies to becquerels and vice versa.

The Activity Decay Calculator (Calculation of Remaining Activity) will calculate how much activity remains, from your specified starting point, after a specified period of time. For example, this calculator will allow you to determine the amount of activity remaining in your 10 mCi vial after the passage of any specified interval of time.

The Chemical Concentration and Labeling Ratio Calculator (Calculation of Ratio of Labeled to Unlabeled Material) is a two-step calculator. The first step uses your specific activity, radiochemical concentration and molecular weight to calculate the chemical concentration of your solution. The second uses the additional entry of theoretical maximum specific activity to calculate the molarities of labeled and unlabeled material present and the ratio of the two.

The Decay Time Calculator (Calculation of Time Taken To Decay To a Selected Activity) works on a similar basis to the Activity Decay calculator, the difference being that for this calculation you supply your initial activity and target activity figures and the calculator works out how long it will take to reach that figure.

The Percentage Decay Calculator (Radioactive Isotope Decay Calculator) is a third variation (after Activity Decay and Decay Time) on the radioactive decay theme. For this calculation, you supply the isotope half-life and the time period over which you want the decay calculated and the calculator works out the percentage of your initial activity which will remain after this specified period.

Volume Calculator will calculate the amount of product in the vial based on pack size and radioactive concentration at the reference date. (Note: To allow for decay in transit we overfill our radiochemical products by a small percentage).

Counts to Activity Calculator (Calculation to convert counts per minute to Curies)will calculate the number of nano Curies (nCi) based on the number of counts per minute (cpm) in the sample and the counter efficiency. (Note: Average counter efficiencies are 40% for tritium and 80% for ¹⁴C, ³²P, ¹²⁵I and ³⁵S).


Please note: Where applicable, for half-life entries we have supplied a list of the isotopes most commonly used in life science applications. Selecting one of the listed isotopes will get its half-life to fill automatically. This half-life is in days (even where the figure is more commonly quoted in years) and is correct according to our reference sources. Up-to-date figures for radioactive half-lives are liable to change from time to time and your laboratories might be using slightly different figures. We have left you the option of entering your own figures by selecting dashes ('--') in the isotope box and filling in the box adjacent to it. This option can be used if you have a half-life figure which varies from ours or if you are using an isotope which is not on our list.

These calculators are accurate to 3 significant figures, but should not be taken to be definitive beyond that point. (For example, answers of 1234 units should be regarded as 1230 units - to the nearest ten.)

These calculators are supplied for guidance only. Amersham Biosciences cannot be held responsible for any inaccuracy or inability to use these calculators.