Calculators

Calculators help you answer financial questions quickly. Test scenarios before making major decisions.

Available Calculators

Compound Interest Calculator

Calculate how investments grow over time with compound returns.

Available now.

Loan & Mortgage Calculator

Calculate monthly payments, total interest, and amortization schedules.

Coming soon.

Savings Goal Calculator

Determine how much to save monthly to reach a target amount.

Coming soon.

Using the Compound Interest Calculator

Inputs

Enter three values to calculate growth:

Principal Amount

The starting balance of your investment.

Examples:

• Initial retirement account balance
• Current savings account amount
• Starting investment principal

Annual Interest Rate

The expected yearly return percentage.

Common rates:

• 3-4% - Savings accounts, CDs
• 5-6% - Bonds, conservative portfolios
• 7-8% - Balanced stock/bond portfolios
• 9-10% - Stock-heavy portfolios

Time Period

How many years the money will grow.

Common periods:

• 5 years - Short-term goals
• 10 years - Medium-term goals
• 20-30 years - Retirement planning

Results

Click Calculate to see:

• Final Amount - Total value at the end of the period
• Total Interest - Earnings from growth alone
• Growth Multiple - How many times the original principal multiplied

Example Scenarios

Retirement Growth

• Principal: $50,000
• Rate: 7%
• Years: 30
• Result: $380,000+ (7.6x growth)

Emergency Fund Growth

• Principal: $10,000
• Rate: 4%
• Years: 5
• Result: $12,200+ (1.2x growth)

College Savings

• Principal: $20,000
• Rate: 6%
• Years: 18
• Result: $57,000+ (2.85x growth)

Comparing Scenarios

Test multiple inputs to compare outcomes:

Rate Comparison

1. Calculate with 6% return
2. Note the final amount
3. Change to 8% return
4. Compare the difference

A 2% higher return over 20+ years produces significantly more wealth.

Time Comparison

1. Calculate with 10 years
2. Note the final amount
3. Change to 20 years (same rate and principal)
4. Compare results

Starting earlier more than doubles the outcome due to compounding.

Principal Comparison

1. Calculate with your current savings
2. Note the final amount
3. Add $5,000 to the principal
4. See how much extra starting capital produces

Understanding Compound Interest

Compound interest means you earn returns on previous returns:

• Year 1: $100 at 10% = $110
• Year 2: $110 at 10% = $121 (not $120)
• Year 3: $121 at 10% = $133.10

Over decades, this “interest on interest” produces most of the growth.

The Rule of 72

Estimate doubling time by dividing 72 by the interest rate:

• 6% return → doubles in ~12 years (72 ÷ 6)
• 8% return → doubles in ~9 years (72 ÷ 8)
• 10% return → doubles in ~7 years (72 ÷ 10)

Best Practices

Use Realistic Rates

Historical stock market returns average 7-10% annually. Use conservative estimates (6-7%) for planning.

Factor in Inflation

The calculator shows nominal returns. Subtract 2-3% for inflation to estimate real purchasing power.

Combine with Budget

Use calculated results to inform your budget:

1. Calculate required savings for your goal
2. Adjust spending to meet that savings target
3. Track progress in Allowealth budgets

Limitations

Simplified Model

The calculator assumes:

• Constant interest rates (rates fluctuate)
• No additional contributions (unrealistic for most)
• No taxes or fees

Use results as estimates, not guarantees.

Not Investment Advice

This tool demonstrates mathematical growth. It does not recommend specific investments or strategies.

Related Features

• Forecast - Project wealth with ongoing contributions
• Budget - Set savings targets based on calculations
• Accounts - Track actual investment balances