The Rich Guy Math · Calculator directory
Choose a money question. Find the calculator that helps you work through it.
Use these financial calculators to explore savings goals, compound growth, debt payments, home loans, retirement, and net worth. Each link takes you to a dedicated calculator page with its explanation.
Start with your own numbers, check the assumptions, and treat projected results as estimates.
Which calculator should I use?
| If you want to know… | Start here |
|---|---|
| How much to save for a target by a deadline | Savings Goal Calculator |
| How much a selected emergency reserve would require | Emergency Fund Calculator |
| How a balance could grow with regular contributions | Compound Interest Calculator |
| How to compare payoff strategies across several debts | Debt Payoff Calculator |
| How extra payments could affect one loan | Loan Payoff Calculator |
| What you own minus what you owe | Net Worth Calculator |
Savings & emergency funds
Start with the goal you want to fund or the reserve you want to build.
How much do I need to save each month?
Savings Goal Calculator
Use your target, current savings, deadline, and assumed APY to estimate the monthly contribution required.
Have ready: target amount, savings already set aside, and months until your deadline.
How much would my chosen reserve cover?
Emergency Fund Calculator
Estimate a reserve from essential expenses and your selected months of coverage. Explore your savings gap and the effect of an unexpected expense.
Have ready: essential monthly expenses, current emergency savings, and a contribution amount.
How could my balance grow over time?
Compound Interest Calculator
Explore a starting balance and regular monthly contributions under an assumed rate. Choose a nominal annual rate or APY and the timing of deposits.
Have ready: starting balance, monthly contribution, timeline, and a clearly identified rate assumption.
For the wider context, explore our budgeting and saving guide.
Debt, credit & home loans
Separate an interest estimate from a payoff plan or a monthly payment estimate.
How do snowball and avalanche compare?
Debt Payoff Calculator
Enter multiple debts and an extra monthly payment to compare modeled payoff paths under the two repayment strategies.
Have ready: each balance, APR, minimum payment, and the extra amount available.
What could an extra payment change?
Loan Payoff Calculator
Estimate the payoff time and interest on one loan using its remaining balance, interest rate, regular payment, and extra payment.
Have ready: current balance and loan payment details from your statement.
What interest might this balance generate?
Credit Card Interest Calculator
Estimate interest from a card balance, APR, and billing-cycle length. Your actual statement can differ when balances change or account terms apply.
Have ready: balance, applicable APR, and days in the billing cycle.
What could my monthly housing payment be?
Mortgage Calculator
Explore a home price, down payment, rate, and term, with inputs for property taxes, homeowners insurance, and HOA fees.
Have ready: estimated purchase and loan details. Check separately for costs the tool does not include.
For the wider context, explore our credit and debt guide.
Investing & retirement
Change the assumptions to explore possibilities. A projected return is not a promised outcome.
How might contributions and a rate affect growth?
Investment Return Calculator
Model an initial investment and monthly contributions over a selected period using an assumed annual return and compounding frequency.
Have ready: investment amount, contributions, horizon, and return assumption.
How do different contribution schedules compare?
Dollar Cost Averaging Calculator
Explore lump-sum and recurring-contribution scenarios. Compare the total amounts contributed as well as the projected ending balances.
Have ready: available lump sum, recurring contribution, timeline, and assumed return.
How could my savings compare with a retirement goal?
Retirement Calculator
Explore current savings, contributions, retirement age, assumed returns, desired annual retirement income, and retirement duration.
Have ready: current age, intended retirement age, savings, and income assumptions.
For the wider context, explore our investing guide.
Your financial position
Take a snapshot of what you own and what you owe.
What are my assets worth after subtracting debt?
Net Worth Calculator
Add assets and outstanding debts to calculate net worth. Use current estimates for asset values and balances rather than original purchase prices.
Have ready: cash, investments, property estimates, and outstanding loan and card balances.
For the wider context, explore our financial planning guide.
A target, a contribution, and a projection answer different questions
Choose what you need to solve before entering a rate. These hypothetical examples exclude interest, fees, and withdrawals.
Solve for a monthly contribution
A $3,000 savings goal
You have $1,000 and want to reach $3,000 in 10 months.
($3,000 − $1,000) ÷ 10
= $200 per month
The savings-goal question starts with an ending target and works back to the contribution.
Solve for a reserve target
Three months of selected expenses
Your essential expenses are $1,500 a month. In this example, you select three months of coverage.
$1,500 × 3 = $4,500
With $1,000 already saved, the gap is $3,500. The coverage period is your assumption; this example does not prescribe it.
A compound-interest projection works in the other direction: you choose the starting balance, contributions, rate, and time, then calculate a possible ending balance. It does not establish the return you will actually earn.
Make the results useful
- Prepare the right inputs. Use current balances and the terms on your statements. Keep an estimated investment return separate from a quoted account rate.
- Read what the tool includes. Check the treatment of fees, taxes, inflation, payment timing, and compounding. Do not assume every calculator handles them identically.
- Compare one change at a time. Change a contribution, payment, timeline, or rate and note what happens. For investing comparisons, check whether the total contributions are equal.
- Turn the result into a question you can act on. Is the contribution affordable? Does the payment cover the modeled interest? Which assumption would most change your plan?
For help fitting the numbers into your wider finances, start with the Personal Finance Guide. You can also compare approaches with the SEC’s Investor.gov compound-interest calculator. Match the assumptions before comparing results.
Questions about using these tools
Why do two calculators give different results?
They may use different contribution timing, compounding conventions, rounding, or treatment of fees and inflation. Compare the inputs and methodology before deciding that one result is wrong.
Which tool should I choose for one loan versus several debts?
Use the Loan Payoff Calculator to explore one loan and extra payments. Use the Debt Payoff Calculator when you want to compare snowball and avalanche across multiple debts.
Do these results guarantee an investment return or loan approval?
No. A modeled result reflects the inputs and method used. Markets, account terms, lender decisions, and your circumstances can produce different outcomes.
Where can I check a calculator’s assumptions?
Open the individual calculator page and read its explanation and methodology alongside the input fields. If something is unclear or appears inconsistent, contact The Rich Guy Math with the tool name and the example inputs, without sharing sensitive account information.