Use this chemistry calculator to reproduce a named relationship with explicit quantities and units for study, laboratory planning, or an independent numerical check.

Isotope 1 mass (u)

Mass of the first isotope.

Isotope 2 mass (u)

Mass of the second isotope.

Average mass (u)

Published average atomic mass.

Solve the two-isotope percent abundances that produce a known weighted-average atomic mass. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Isotope 1 abundance (%)

Percent abundance of the first isotope.

Isotope 2 abundance (%)

Percent abundance of the second isotope.

• Radioactive and nuclear calculations require the correct isotope, decay mode, mass convention, and time unit. Branching, daughter products, detector efficiency, shielding, and uncertainty in tabulated nuclear data may require a fuller model.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check units and significant figures, compare the result with limiting cases, and use measured or source-specific constants where available. Laboratory, safety, and regulatory decisions require validated methods and appropriate uncertainty analysis.

• Isotope Average Mass Calculator

  Compute the weighted-average atomic mass from isotope masses and their percent abundances.

• Isotope Pattern Ratio

  Estimate the M+1 to M peak intensity ratio from carbon count times 0.011 for natural 13C abundance of 1.1 percent.

• Nuclear Packing Fraction Calculator

  Calculate the conventional nuclear packing fraction from isotopic atomic mass and mass number, reported in parts per ten thousand.