The amount you have already invested or saved, or the initial balance. This amount will not be affected by any delay of new savings.
Amount of money you are planning to add to the savings during each period.
Life of the investment or savings.
Rate of return
Your expected yearly rate of return. The type of investment you choose has an effect on the actual rate of return. For example, the average annual compounded rate of return for the 10 years S&P 500 ended on 2012 was about 7.10%. Bank or savings institutions can pay as little as 0.25% to 1% on savings accounts. It is important to know that future rates of return cannot be foreseen and investments that pay higher rates of return have a higher risk and are more volatile.
Years to postpone saving
Number of years by which you have delayed or want to delay the savings.
Frequency of contributions
How frequently you put in money to the account. This calculator has used this term as Contribution Interval. Whatever, you can choose per month, per quarter, or per year as your frequency of contributions.
Cost of waiting
Amount of money you are earning less for delaying your savings. In one sense, this is the opportunity cost of forgoing savings by choosing consumptions.
This is the amount of contributions you need to make now to earn the same you could do from a timely investment or saving.