Calculator help

Start with the worked example

Each calculator opens with example inputs. Select Reset example to restore them. Compare your result with the worked example beneath the form.

If an input is rejected

Read the error above the inputs, then check the units and any empty fields. Every matrix row needs the same number of entries, and a fraction cannot have zero as its denominator. Values such as Infinity and NaN are not accepted.

Results and downloads

Select Calculate after changing values. Old results are cleared when inputs change. Use Download calculation (.json) to save a local record of the inputs, results, and steps. The website cannot reopen these files to continue a calculation.

Browser requirements

Use a recent version of Chrome, Firefox, or Safari, with JavaScript turned on to run calculations. You can still read the equations, assumptions, and examples with JavaScript turned off.

Report a problem

Email [email protected]. Tell us which calculator you used, what happened, and what you expected. If you can share the inputs without revealing confidential information, include them with your browser version and the error message. A reference for the expected answer helps us check a calculation problem.