Greenside.money — Choose the side of interest that works for you.

Green Side — Investor’s Boost: we stretch to 10 years so compounding has room to show up.

Red Side — Credit Card Trap: we zoom in on the first year and highlight how long payoff takes.

Red Side: Credit Card Trap Red Side — interest you pay

You carry a balance instead of paying in full. Interest keeps getting added on top of interest. Adjust the numbers and watch how much goes to the bank.

Timeline: first 12 months shown below Compounding: daily (simulated monthly)

Scenario presets

Pick a story to auto-fill the sliders.

Start with your own numbers or tap a scenario to drop into a story.

Starting balance $1,500

How much you already owe on your card.

APR (interest rate) 24.99%

Typical card APR is often 20–30%.

Monthly payment $75

Try the minimum… then try doubling it.

Interest paid in 1 year

Money that goes to the bank, not your balance.

Balance after 1 year

What you still owe after 12 months.

Time to pay off in full*

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Where do your payments go?

...

Interest Principal reduced

Month-by-month snapshot

First 12 months

Month 1 Month 12

Story of this year

You pay $0 this year; ...

Try this: Slide APR up and payment down—watch amber grow and payoff time stretch.

*Assumes you stop using the card for new purchases.

Green Side: Investor’s Boost

Interest you earn

Time frame: 10 years, compounding monthly.

Starting amount $500

A small beginning still matters.

Monthly contribution $75

Money you add each month.

Average annual return 7%

Historically, stock markets have averaged ~7% after inflation.

Real returns bounce around; 7% is a historical average, not a guarantee.

The Green Side over time —

Keep the same investing habit humming for ~50 years and the green wedge eventually rockets past your own deposits.

Deposits Compounding lift

Let the plan ride for decades and compounding eventually hurls your balance into the stratosphere.

Total invested

Your own dollars over 10 years.

Growth from interest

Money your money earned for you.

What builds your future?

$0 after 10 years

Money you put in Growth from interest

Year-by-year snapshot

10-year view

Year 1 Year 10

Story of these 10 years

Try this: Small monthly additions + time shift more bars to green.

What is compound interest? Read me first

Compound interest means you pay interest on interest or earn interest on interest. Either way, yesterday’s interest joins the pile and starts affecting tomorrow.

With debt, that pile works against you: if you only make small payments, your balance barely shrinks while interest keeps stacking. With investing, the same math works in your favor: your money grows faster the longer you leave it alone.

How to use this coach

Start on the Green Side. Set a starting amount and monthly contribution.
Open the schedule to see how much is your deposits vs growth.
Switch to the Red Side. Set a card balance and APR, then adjust the payment.
Compare the curves—same math, opposite direction. Interest is either a cost or a teammate. You choose the side.

Quick rules of thumb

For credit cards: Pay in full whenever you can. If you can’t, aim for more than the minimum and stop new spending.
Keeping balances below ~30% of your limit usually helps your credit score.
For investing: Start small and automatic. Time in the market matters more than timing the market.
Same math, opposite outcomes: interest is either a cost or a teammate. The slider positions decide which.

Start on the Green Side, then compare it with the Red Side