Smart Financial Calculators

Drag the sliders and watch the numbers — and the charts — update instantly. Every tool is free and runs entirely in your browser.

Loan details

Loan amount

Annual interest rate

Term

Tip: shortening a 30-year term to 20 years raises the monthly payment less than most people expect — but often cuts total interest nearly in half.

Monthly payment

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Total interest

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Total paid

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What you repay: principal vs interest

Remaining balance over time

Investment plan

Starting amount

Monthly contribution

Expected annual return

Years invested

Context: broad stock index funds have returned ~7–10% per year over long periods, before inflation. Past performance never guarantees the future.

Future value

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You contribute

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Growth earned

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Projected growth

Your retirement picture

Current age

Retirement age

Desired monthly spending in retirement

Already saved

Monthly saving

Expected annual return

Target nest egg

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25× annual spending (4% rule)

Projected at retirement

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Savings projection to retirement

Your income

Monthly take-home income

How the 50/30/20 rule works

50% Needs — rent or mortgage, groceries, utilities, transport, insurance premiums, minimum debt payments.
30% Wants — dining out, streaming, travel, hobbies, upgrades you could live without.
20% Savings & debt — emergency fund, investments, retirement, and extra debt payments beyond minimums.

If needs exceed 50% where you live, trim the wants share first — never the savings share.

Your monthly split

Needs · 50%

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Wants · 30%

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Save · 20%

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Saving — a year at this rate — invested at 8%, that's roughly — after 10 years.