InvestmentCalculators
Investment

Investment Calculators

Seven precision tools for projecting, comparing, and understanding investment growth. Real-time inputs, beautiful charts, and educational context for every calculation.

The original wealth-building formula.

Compound Interest

See how your money grows over time with the power of compounding.

Project your full portfolio trajectory.

Investment Growth

Project your portfolio's trajectory with initial capital and recurring contributions.

Regular buys vs the market.

DCA

Simulate regular recurring investments and compare against lump-sum entry.

Reinvested dividends, compounded.

DRIP

Model accumulating shares and dividend income with full reinvestment.

Your real annualized return.

CAGR

Calculate the true compound annual growth rate of any investment.

Mental math for doubling time.

Rule of 72

Estimate how long it takes for money to double at a given rate.

Strategy head-to-head.

Lump Sum vs DCA

Compare investing everything at once against spreading purchases over time.

How to choose the right investment calculator

The seven calculators in this section answer progressively richer questions. At the simplest level, the Compound Interest Calculator shows how a starting balance grows at a constant rate — the canonical starting point for understanding investment math. Adding recurring contributions transforms it into the Investment Growth Calculator, which projects the future value of most real-world portfolios (starting capital plus ongoing monthly savings).

For investors deploying cash on a schedule rather than all at once, the Dollar-Cost Averaging (DCA) Calculator models weekly, biweekly, monthly, or quarterly purchases, while the Lump Sum vs DCA Calculator directly compares both strategies over the same horizon. Historical data from Vanguard and other large asset managers suggests lump sum wins roughly two-thirds of the time in rising markets — but DCA offers real behavioural protection during volatility.

Dividend-focused investors should start with the DRIP Calculator, which models not just compounding but the three-dimensional growth of share count, dividend-per-share, and share price. Over multi-decade horizons, reinvested dividends typically account for 40 – 50% of total equity returns. The CAGR Calculator reverses the problem: given a start and end value over a known time, what constant annual rate would have produced it? CAGR is the standard benchmark for comparing any two investments over the same horizon.

Finally, the Rule of 72 Calculator provides the mental-math shortcut every investor should internalize: 72 ÷ annual rate ≈ years to double. At 7%, money doubles roughly every 10 years; at 10%, every 7. The exact doubling time from the compound interest formula is shown alongside as a reference.

Frequently asked

About investment calculators

Which investment calculator should I start with?
If you are new to investing, start with the Compound Interest Calculator. It shows how a starting amount grows over time at a constant return, with optional monthly contributions. Once that feels intuitive, the Investment Growth Calculator adds realistic portfolio behaviour (initial capital plus ongoing monthly savings compounded monthly). For understanding timing decisions, the DCA Calculator and Lump Sum vs DCA Calculator compare strategies head-to-head.
What return rate should I enter?
For diversified equity portfolios, 7% real (inflation-adjusted) or 10% nominal are common multi-decade reference points derived from the S&P 500. For balanced 60/40 portfolios, 4 – 5% real is reasonable. For bond-heavy portfolios, 2 – 3% real. Always use real returns when planning in today's dollars, and treat any single rate as an illustration — actual returns vary significantly year to year.
Does the DCA calculator account for market volatility?
No, all calculators in this section use a constant assumed return. That choice keeps the math clean and the comparison fair, but it means the projections will be smoother than real market trajectories. Real DCA outperforms a constant-return projection during volatile or declining markets (because fixed-dollar purchases buy more shares when prices drop) and under-performs during steady rallies.
Is the DRIP calculator realistic for dividend-growth stocks?
The DRIP Calculator uses three independent growth rates — dividend yield, annual dividend growth, and share price appreciation — giving it enough flexibility to model Dividend Aristocrats, REITs, or high-yield utilities reasonably well. Real companies grow dividends unevenly and may cut them during stress, so treat the output as an illustration of DRIP mechanics rather than a forecast for a specific ticker.
How is CAGR different from average annual return?
Simple averages hide the asymmetry of compound losses and gains. A fund that gains 50% one year and loses 30% the next did not 'average' 10%; its CAGR is about 2.5%. CAGR = (EndValue / StartValue)^(1/years) − 1 captures the true geometric average — the constant rate which, compounded annually, would have produced the observed result.
Why does the Rule of 72 use 72 instead of 69.3?
Mathematically the doubling-time constant is ln(2) × 100 ≈ 69.3. But 72 has significantly more integer divisors (2, 3, 4, 6, 8, 9, 12, 18, 24, 36) which makes the division easier to do in your head. The calculator shows the exact result alongside the Rule of 72 approximation so you can see how small the error is at realistic rates.