What is compound interest and how does it work?

Want your money to grow without constantly adding more to it? That’s the power of compound interest.

Compound interest is one of the most effective ways to build savings over time because it allows your money to earn returns on both your original balance and the earnings already added to it. The longer your money stays in an account and continues to grow, the more powerful compounding can become.

Whether you are building an emergency fund, saving for a future goal or simply looking for smarter ways to grow your balance, understanding compound interest can help you make better decisions.

What is compound interest?

Compound interest is the process of earning returns on both your original deposit and the interest or dividends already added to your account.

Unlike simple interest, which only earns based on your starting balance, compound interest allows previous earnings to continue generating growth.

For example:

• You deposit $1,000 into savings
• Your account earns interest
• The next time earnings are calculated, they are based on your original $1,000 plus the earnings already added

Over time, this creates a snowball effect where growth can continue building on itself.

How compound interest works

Compound interest depends on a few key factors:

• Your starting balance

  The more money you begin with, the more opportunity there is for earnings to build.

• Your interest rate or APY

  A higher annual percentage yield, or APY, can help your balance grow faster.

• How often earnings are added

  Interest may be added daily, monthly or quarterly depending on the account. More frequent compounding can help increase growth over time.

• Time

  Time is one of the most important ingredients. The longer your money remains in the account, the more opportunities it has to compound.

Why compound interest matters

Compound interest can make a meaningful difference in how quickly your savings grow.

• It helps your money grow faster

  Because you are earning on previous earnings, balances can increase more efficiently over time.

• It rewards starting early

  Even small balances can grow significantly when given enough time.

• It makes consistency more valuable

  Regular contributions paired with compounding can create strong long-term results.

• It builds momentum

  Watching your savings grow can encourage better financial habits and continued progress.

Compound interest example

Let’s compare two savers who each deposit $5,000 and leave it untouched for five years.

Saver A

$5,000 in an account earning 0.05% APY could grow to about $5,012.52 after five years.

Saver B

$5,000 in an account earning 5.00% APY could grow to about $6,381.41 after five years.

That is a difference of more than $1,300, without adding another dollar.

This example shows how choosing a stronger rate can have a major impact over time.

For illustrative purposes only. Actual earnings may vary based on rates, compounding frequency and account activity.

Where to earn compound interest

Several account types can help you benefit from compounding:

• High-yield savings accounts

  These accounts often offer stronger APYs than traditional savings accounts while keeping funds accessible.

• Certificates of deposit

  CDs may offer competitive returns in exchange for keeping money deposited for a set term.

• Money market savings accounts

  These accounts can combine savings features with competitive earnings, depending on the institution.

• Retirement and investment accounts

  Stocks, bonds and mutual funds may offer growth potential, but values can rise and fall and are not federally insured.

Federal protection matters

Savings accounts at banks are typically insured by the Federal Deposit Insurance Corporation or FDIC. Credit union savings accounts are typically insured by the National Credit Union Administration or NCUA. This can provide added confidence for savers, especially those with larger balances.

How to maximize compound interest

You do not need a large balance to benefit from compounding. A few smart habits can make a big difference.

• Start now

  The sooner you begin, the more time your money has to grow.

• Choose a competitive APY

  A stronger rate can significantly improve long-term results.

• Add money consistently

  Regular deposits can accelerate growth and build momentum.

• Reinvest earnings

Keeping your earnings in the account allows them to continue compounding.

How round up savings can supercharge compound interest

At credit unions, earnings on deposit accounts are called dividends instead of interest. While the terminology is different, the idea is similar. Your money earns returns over time based on your balance and the account rate, helping your savings continue to grow.

With Solarity’s Round Up Savings program¹, everyday debit card purchases round up to the nearest dollar and the spare change is automatically directed into a Solarity Savers account earning up to 5.00% APY². And with compounding growth, these small deposits become more powerful over time.

That means everyday spending can quietly contribute to long-term savings growth through:

• Automatic contributions from routine purchases
• A competitive APY that helps balances compound faster
• Consistent momentum without needing large deposits
• A simple way to build savings habits over time

Instead of waiting until you have extra money to save, round ups can help you start with what you are already spending.

Start small and let compound interest do the work

You do not need a large balance to benefit from compound interest. Starting with small automatic contributions and the right savings account can create real progress over time.

Whether you are just getting started or looking to make your current savings work harder, combining Round Up Savings with Solarity Savers can be a smart way to grow your money steadily.

¹ Upon enrollment in Round Up Savings, Solarity debit card purchases in your linked checking account will be rounded up to the nearest dollar and transferred to your Solarity Savers account. Transfers occur daily when sufficient funds are available.

² Annual Percentage Yield (APY) effective as of 4.28.26; rates subject to change after account opening. $5 minimum to open; $0.01 minimum to earn APY. To earn the advertised APY, post and settle 20+ member-initiated transactions per month in a linked Solarity checking account. If qualifications are not met, account will earn 0.05% APY. Limit one Solarity Savers account per membership; not available for businesses. Fees may reduce earnings.