How this calculator works
Compounding and contribution frequencies are independent. The known rate can be nominal or effective, contributions can arrive at interval starts or completed interval ends, and their amount can grow at a stated effective annual rate. The schedule separates contributed capital from growth. Rate mode solves for the nominal quote needed to reach a target. Inflation adjusts only purchasing power, not the account balance. The opening row includes the first beginning deposit when the horizon is positive; later exact-boundary rows show the closing balance before the next beginning deposit.
Formula
F = P exp(kt) + sum(C_j exp(k(t-t_j))). For nominal j compounded m times yearly, k = m ln(1+j/m); for an effective annual rate e, k = ln(1+e). Contributions C_j can grow at (1+g)^(j/f).
Worked example
An initial $1,000 at 10% compounded annually plus $100 at each year end reaches $1,420 after two years: $1,200 contributed and $220 growth. Moving both deposits to the beginning raises the balance to $1,441.
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Frequently asked questions
How are partial periods treated?
The balance earns fractional-period exponential growth. End deposits require a completed interval. Beginning deposits occur at interval starts before the horizon, including the start of a partial final interval. A zero-length term has no scheduled deposits.
Does the target solver guarantee an investment return?
No. It finds a constant mathematical rate under your assumptions. Real returns and contribution schedules can differ.
Why use a table rather than a chart?
The table gives the modelled balance and its contribution/growth breakdown at each selected reporting interval. Tables display the first 500 rows of a longer computed schedule. Choose yearly reporting to see a long horizon in full.