Compound Interest & Investment Calculator
Simulate how regular investments grow exponentially over time. Model inflation erosion, compounding frequency, and retirement cash flows in real time.
⚙️ Investment Parameters
In today's purchasing power (2.5% inflation)
($13,751.13 annually in retirement)
Capital Composition
Composite
Year-by-Year Growth Schedule
Mathematical breakdown of balance growth, annual interest, and constant-dollar purchasing power.
| Year | Total Deposits | Annual Interest | Total Interest | End Balance (Nominal) | Real Value (Today's $) | Retirement/Mo (4%) |
|---|---|---|---|---|---|---|
| 1 | $16,000.00 | +$1,054.96 | $1,054.96 | $17,054.96 | $16,638.98 | $56.85 |
| 2 | $22,000.00 | +$1,640.52 | $2,695.47 | $24,695.47 | $23,505.51 | $82.32 |
| 3 | $28,000.00 | +$2,274.68 | $4,970.15 | $32,970.15 | $30,616.06 | $109.90 |
| 4 | $34,000.00 | +$2,961.47 | $7,931.62 | $41,931.62 | $37,987.98 | $139.77 |
| 5 | $40,000.00 | +$3,705.27 | $11,636.89 | $51,636.89 | $45,639.48 | $172.12 |
| 6 | $46,000.00 | +$4,510.80 | $16,147.68 | $62,147.68 | $53,589.75 | $207.16 |
| 7 | $52,000.00 | +$5,383.19 | $21,530.87 | $73,530.87 | $61,858.97 | $245.10 |
| 8 | $58,000.00 | +$6,327.99 | $27,858.86 | $85,858.86 | $70,468.37 | $286.20 |
| 9 | $64,000.00 | +$7,351.21 | $35,210.07 | $99,210.07 | $79,440.32 | $330.70 |
| 10 | $70,000.00 | +$8,459.35 | $43,669.42 | $113,669.42 | $88,798.37 | $378.90 |
| 11 | $76,000.00 | +$9,659.47 | $53,328.89 | $129,328.89 | $98,567.34 | $431.10 |
| 12 | $82,000.00 | +$10,959.20 | $64,288.09 | $146,288.09 | $108,773.37 | $487.63 |
| 13 | $88,000.00 | +$12,366.80 | $76,654.89 | $164,654.89 | $119,444.01 | $548.85 |
| 14 | $94,000.00 | +$13,891.24 | $90,546.13 | $184,546.13 | $130,608.31 | $615.15 |
| 15 | $100,000.00 | +$15,542.20 | $106,088.33 | $206,088.33 | $142,296.89 | $686.96 |
| 16 | $106,000.00 | +$17,330.19 | $123,418.52 | $229,418.52 | $154,542.03 | $764.73 |
| 17 | $112,000.00 | +$19,266.59 | $142,685.10 | $254,685.10 | $167,377.79 | $848.95 |
| 18 | $118,000.00 | +$21,363.70 | $164,048.81 | $282,048.81 | $180,840.08 | $940.16 |
| 19 | $124,000.00 | +$23,634.87 | $187,683.68 | $311,683.68 | $194,966.78 | $1,038.95 |
| 20 | $130,000.00 | +$26,094.55 | $213,778.24 | $343,778.24 | $209,797.87 | $1,145.93 |
The Rule of 72 & Compounding Frequency
The Rule of 72 is a mental shortcut to estimate how many years it takes for your investment to double: divide 72 by your annual interest rate. At an 8% annual return, capital doubles every 9 years (72 / 8 = 9). More frequent compounding (e.g. daily or monthly vs annual) yields slightly higher effective annual rates (APY) via continuous compounding:
Nominal vs. Real Inflation-Adjusted Returns
A portfolio with an 8% nominal annual return during a 2.5% inflation environment yields approximately a 5.37% real rate of return under the Fisher equation (1 + r_nominal = (1 + r_real)(1 + i)). Calculating both nominal and real future values allows retirees to understand their actual purchasing power in terms of today's cost of living.