Investing7 min read
The simple math behind why your 20s matter most.
A single year of contributions at 25 can outpace ten years starting at 40. Here's the model that shows why — and how to use it.
May 2026Read
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Compound interest · live model
Balance in 20 years
$300,851
2.3x your contributions
Contributions $130KInterest earned $171K
Starting balance$10,000
$
Monthly contribution$500
Annual return7.0%
Time horizon20 years
Compound frequency12x/yr
Assumes constant return — actual markets vary.Full breakdown
Built for clarity
7 Free CalculatorsNo Sign-up RequiredBrowser-only ProcessingFDIC & IRS Data SourcesUpdated 2026
The toolkit
Seven calculators.
One workspace.
Every tool is free, runs in your browser, and keeps your data private. No sign-up required.
Most used
Compound interest
Model how contributions and time multiply your money.
Mortgage
Monthly payment, total interest, and full amortization table.
PopularRetirement planner
Project the nest egg you'll have, and what it spins off monthly.
Loan calculator
Personal, auto, student — payments and payoff schedules.
Investment growth
Model portfolio performance with contribution strategies.
Savings goal
Reverse-engineer the monthly habit to hit a target.
Rent vs. buy
Should you rent or buy? Compare the true cost of each path.
Sample comparison · illustrative only
Where the best rates live this week.
| Provider | APY | Min. deposit | Rating | |
|---|---|---|---|---|
M Marlowe BankTop rate Online savings · FDIC | $0 | 4.8 | ||
N North Ridge Money market account | $100 | 4.7 | ||
C Crestline Financial Premier savings · FDIC | $0 | 4.6 | ||
C Coastline Credit Union Member savings · NCUA | $5 | 4.5 | ||
H Heritage Bank Online-only savings | $0 | 4.3 | ||
P Pinnacle Trust Smart saver account | $500 | 4.2 |
Sample rates for illustration only — not live data. Actual rates vary by provider. We may earn a referral fee.See full methodology
Learn — Field notes
Plain-spoken guides to the math behind money.
Borrowing5 min read
Best mortgage calculators compared for 2025.
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Planning9 min read
Best retirement calculators compared for 2025.
From simple projections to Monte Carlo simulations — we compared the top free retirement calculators so you don't have to.
Apr 2026Read
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