Interest Calculator
Compound interestSee how your savings can grow with compound interest, an initial deposit, and regular contributions. Solve for end balance, years to reach a goal, required interest rate, or how much to save.
| Year | Start Balance | Contribution | Lump Sum | Interest | End Balance |
|---|---|---|---|---|---|
| Start | $10,000 | $0 | — | $0 | $10,000 |
| 1 | $10,000 | $6,000 | — | $763.26 | $16,763.26 |
| 2 | $16,763.26 | $6,000 | — | $1,169.06 | $23,932.32 |
| 3 | $23,932.32 | $6,000 | — | $1,599.2 | $31,531.53 |
| 4 | $31,531.53 | $6,000 | — | $2,055.16 | $39,586.68 |
| 5 | $39,586.68 | $6,000 | — | $2,538.47 | $48,125.15 |
| 6 | $48,125.15 | $6,000 | — | $3,050.77 | $57,175.92 |
| 7 | $57,175.92 | $6,000 | — | $3,593.82 | $66,769.74 |
| 8 | $66,769.74 | $6,000 | — | $4,169.45 | $76,939.19 |
| 9 | $76,939.19 | $6,000 | — | $4,779.62 | $87,718.81 |
| 10 | $87,718.81 | $6,000 | — | $5,426.39 | $99,145.2 |
| 11 | $99,145.2 | $6,000 | — | $6,111.98 | $111,257.17 |
| 12 | $111,257.17 | $6,000 | — | $6,838.69 | $124,095.87 |
| 13 | $124,095.87 | $6,000 | — | $7,609.02 | $137,704.89 |
| 14 | $137,704.89 | $6,000 | — | $8,425.56 | $152,130.44 |
| 15 | $152,130.44 | $6,000 | — | $9,291.09 | $167,421.53 |
| 16 | $167,421.53 | $6,000 | — | $10,208.56 | $183,630.09 |
| 17 | $183,630.09 | $6,000 | — | $11,181.07 | $200,811.16 |
| 18 | $200,811.16 | $6,000 | — | $12,211.93 | $219,023.09 |
| 19 | $219,023.09 | $6,000 | — | $13,304.65 | $238,327.74 |
| 20 | $238,327.74 | $6,000 | — | $14,462.93 | $258,790.67 |
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Get started freeFor illustration only. Interest and returns are not guaranteed. This calculator does not constitute financial advice. Consider consulting a qualified financial advisor for your situation.
About this calculator
This calculator projects the growth of savings using compound interest and optional periodic contributions. It is for anyone planning for a goal (e.g. emergency fund, down payment, or a target balance) and wants to see how much they will have, how long it will take, or what rate or contribution is needed.
Use it for interest-based growth (savings accounts, GICs, bonds) rather than volatile investment returns. You can solve for end amount, years to goal, required interest rate, initial lump sum, or periodic contribution. Advanced options include inflation (real dollars), tax on growth, and lump sums in a specific year. The year-by-year table and chart show how balance and interest build over time.
How this is calculated
What this calculator does
The Interest Calculator projects the future value of your savings using compound interest plus optional periodic contributions. Each period (e.g. monthly), interest is applied to the current balance at a periodic rate derived from your annual rate, and then your contribution is added—or added first, then growth, if you choose "beginning of period." The table shows year-by-year: starting balance, contributions, interest earned, and ending balance.
Periodic rate and balance growth
The annual interest rate is converted to a periodic rate based on how often you contribute (e.g. monthly, quarterly):
periodicRate = (1 + annualRate)1/k − 1
where k is the number of periods per year (e.g. 12 for monthly). Example: 6% annual with monthly contributions gives (1 + 0.06)^(1/12) − 1 as the monthly rate. Each period the balance grows by this rate, then the contribution is added (or contribution first if beginning of period). So:
balancenext = balance × (1 + periodicRate) + contribution
Interest earned in a year = ending balance − starting balance − contributions − lump sums added that year.
Solve-for modes and optional features
You can solve for end amount, years needed, interest rate, initial investment, or periodic contribution. Advanced options include inflation (today’s dollars), tax on growth, lump sums in a specific year, and contribution limits. Results are for illustration only and do not guarantee future returns.
When to use this vs the Investment Calculator
Use the Interest Calculator for interest-based growth (savings accounts, GICs). The Investment Calculator uses the same math but is framed for investment returns. Both support inflation and tax in Advanced.
Assumptions
We assume the interest rate is constant over the entire period and that contributions are made on the schedule you choose (beginning or end of period). Inflation and tax, if enabled, use the rates you enter. This calculator does not constitute financial advice.
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