Compound Interest, Explained Without the Jargon
There is a concept in personal finance that every textbook calls 'the eighth wonder of the world.' Einstein may or may not have said that. What is definitely true is that most people understand the phrase before they understand the thing it's describing — and the gap costs them money for decades.
Simple Interest vs Compound Interest
Simple interest is straightforward. You put GHS 1,000 in an account at 10% per year. After year one, you have GHS 1,100. Year two, another GHS 100. Year ten, GHS 2,000. You earned GHS 100 every year on the original GHS 1,000.
Compound interest is different. In year one, you also earn GHS 100 on GHS 1,000. But in year two, you earn 10% on GHS 1,100 — so GHS 110, not GHS 100. In year three, 10% on GHS 1,210. The interest earns interest. That difference sounds small early on. It becomes enormous over time.
The Numbers That Change How You Think
GHS 1,000 at 10% per year:
After 10 years with simple interest: GHS 2,000
After 10 years with compound interest: GHS 2,594
After 20 years with compound interest: GHS 6,727
After 30 years with compound interest: GHS 17,449
The original principal is still GHS 1,000. The extra GHS 15,449 after 30 years was earned entirely by interest compounding on itself. No extra contributions. Just time.
Why Ghana's High Rates Make This Even More Powerful
In Ghana, savings and investment instruments often carry higher nominal interest rates than you'd find in Europe or North America. A 91-day T-bill at 27% annualised or a unit trust averaging 20% per year means compound growth happens faster. The flip side is that Ghana also has inflation to contend with. What matters for real wealth is compound growth in excess of inflation — but even net-of-inflation rates in Ghana have historically offered genuine purchasing power growth for patient investors.
The Rule of 72
There's a shortcut worth knowing: divide 72 by your annual interest rate to get the approximate number of years it takes to double your money. At 20%, your money doubles in about 3.6 years. At 10%, it's 7.2 years. At 5%, it's 14.4 years. This rule helps you quickly evaluate whether an investment's return is worth your time.
Starting Matters More Than Amount
The most common mistake is waiting until you have 'enough' to start investing. Compound interest rewards time more than it rewards size. GHS 200 invested today at 20% per year for 20 years grows to GHS 7,668. GHS 1,000 invested in 10 years for 10 years at the same rate grows to GHS 6,192. Start small, start now.