Investment Calculator

Three numbers tell different stories

An investment projection should separate:

1. Contributions: money deposited by the investor.
2. Investment growth: the ending balance minus those deposits.
3. Purchasing power: what the future balance may buy after inflation.

This calculator reports all three. The nominal balance is the account value shown in future dollars. The inflation-adjusted balance translates it into today’s dollars. Neither is guaranteed.

How the projection works

The model converts the assumed annual return after recurring fees into an equivalent monthly rate. Each month it grows the existing balance and then adds the contribution:

next balance = current balance × (1 + monthly net return) + contribution

Net return is the selected annual return minus the annual fee assumption. The model repeats that process for the selected number of years and records an annual series for the chart.

The investment fee calculator isolates fee drag by running the same scenario with and without fees. This page instead focuses on the complete future-value projection.

Worked example

Start with $10,000, invest $500 per month for 30 years, assume a 7% annual return, a 0.25% recurring fee, and 2.5% inflation. Contributions total $190,000.

Compounding can lift the nominal result far above total deposits, but the balance in today’s dollars is materially lower because three decades of inflation reduce purchasing power. Both numbers matter: nominal dollars describe the future statement; real dollars help plan future spending.

Return assumptions deserve a range

A single projection can create false confidence. Run at least three cases:

• a lower-return case for weak markets or a conservative portfolio;
• a middle planning case; and
• a higher case that is possible but not required for the plan to work.

Also change the contribution. Savings behavior is controllable; market returns are not. A plan that succeeds only under the highest return assumption is fragile.

Fees compound in the wrong direction

A recurring fee looks small because it is quoted as a percentage. Its effect includes both the amount deducted and the growth that deducted money can no longer earn. Over long periods, a one-percentage-point difference can produce a large gap.

Review fund expense ratios, advisory fees, retirement-plan charges, and any overlapping layers. Do not add the same fee twice when an all-in fee already includes an underlying cost.

Inflation changes the meaning of a target

A $1 million balance in 30 years will not buy what $1 million buys today. The calculator divides the nominal balance by cumulative assumed inflation to estimate current purchasing power. Use the inflation calculator to explore that relationship directly.

Common mistakes

1. Treating an average return as a promise. Markets are volatile and annual outcomes arrive in an uneven sequence.
2. Ignoring fees. Small recurring costs compound for the full holding period.
3. Comparing future dollars with today’s expenses. Use the real balance for purchasing-power planning.
4. Assuming taxes are included. Account location and tax rules can change the amount kept.
5. Using only one scenario. A useful plan survives less favorable assumptions.

This calculation is educational and does not recommend a security, asset allocation, return assumption, or investment strategy.