Annual return needed to grow a lump sum to a target over a fixed period.

To grow 10,000 into 20,000 over 10 years you need roughly 7.18% a year compounded — well above a cash savings rate and roughly in line with long-term equity averages. To double it in 5 years you need nearly 15% a year, which is very optimistic for any non-speculative asset.

How to use it

Enter the current amount you have, the target value you want to reach, and the number of years. No contributions — the maths assume a single lump sum growing on its own.

What the result means

The primary figure is the compound annual rate required. Compare it to realistic rates for each asset class before committing: cash savings (2-5% typically), government bonds (3-5%), global equities (5-8% long-term average), high-risk assets (wildly variable and volatile).

When the required return looks impossible

Three honest options: stretch the time horizon, lower the target, or add regular contributions. For contribution-based goals, use the Monthly Savings Goal tool instead — it's designed for that.

Quick example

With current amount of 10,000 and target amount of 20,000 (plus years of 10 years), the result is 7.18%. Change any figure and watch the output shift — it's often more useful to see the pattern than to memorise the formula.

Which inputs matter most

You enter Current Amount, Target Amount, and Years. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.

What's happening under the hood

Solves the compound-growth equation for the annual rate: rate = (target/current)^(1/years) - 1. Assumes a single lump sum with no additional contributions, annual compounding, and no withdrawals or taxes. For goals with ongoing contributions, use the savings-goal tool instead. The formula is listed in full below. If the number looks off, you can retrace the calculation by hand — that's the point of showing the working.

Using this well

Treat the output as one point on a wider map. Run it three times — a pessimistic case, a central case, and a stretch case — and plan against the pessimistic one. That habit alone separates people who stick with an investment plan from those who bail at the first wobble.

What this doesn't capture

Steady-rate math ignores real-world volatility. Actual returns are lumpy; sequence-of-returns risk matters most in drawdown; fees and taxes drag on compound growth; and behaviour changes in drawdowns can reduce outcomes below the projection. Treat the number as one scenario, not a forecast.