Return Needed Calculator

To grow 10,000 into 20,000 over 10 years requires roughly 7.18% a year compounded — above typical cash savings rates and roughly in line with long-term equity averages. To double it in 5 years requires nearly 15% a year, which is uncommon for non-speculative assets.

How to use it

Enter the current amount, the target value, 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 historical or expected rates for each asset class: cash savings (typically 2-5%), government bonds (3-5%), global equities (5-8% long-term average), high-risk assets (variable and volatile).

When the required return appears difficult to achieve

Three options: extend the time horizon, lower the target, or add regular contributions. For contribution-based goals, the Monthly Savings Goal tool estimates amounts needed with ongoing deposits.

Quick example

With current amount of 10,000 and target amount of 20,000 over 10 years, the result is 7.18%. Changing any figure shifts the output — observing the pattern across variations can clarify the relationship between inputs and required rate.

Which inputs matter most

Inputs are Current Amount, Target Amount, and Years. Each input carries different weight in the final result. Adjusting one input toward extreme values shows which movements affect the required rate most significantly.

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, the savings-goal tool is designed for that scenario. The formula appears in full below. If the number appears inconsistent, retrace the calculation by hand — the working is shown to permit verification.

Using this well

What this doesn't capture

Steady-rate math does not account for real-world volatility. Actual returns vary by period; sequence-of-returns risk concentrates during drawdown phases; fees and taxes reduce compound growth; and behaviour changes during market stress can produce outcomes below the projection. The calculated rate represents one scenario rather than a forecast.