Period method: When the periodic investment start relative to the deposit frequency. If the first investment is assumed to be made "today", then select "start-of-period," otherwise select "end-of-period."
Compound frequency: If the compounding frequency is not specified or you don't know it, then select the same value as "deposit frequency."
Step values: By how much to increase the x-axis and y-axis values from their initial values. For example, if you've set the "initial interest rate" to 5% and if you set the "rate step value" to 0.5% then the calculator will set the second value for the interest rate (x-axis) to 5.5%.
On the "Future Value" tab you can calculate a matrix of future values for a given deposit / investment amount while varying the term and interest rate at which the investment is made.
The "Deposit Amount" tab allows you to calculate a matrix of investment amounts (deposits) required to reach a given future value for different terms and interest rates.
The "step amounts" on either tab control how much the interest rate and term are going to increase.
Note: It is not necessary to clear one calculation before doing the next. You can change one value and recalculate.
Comments, suggestions & questions welcomed...