Compound Interest Calculator
What Is Compound Interest? Formula and Examples
Compound interest grows a balance on a growing base. Here is the formula, a $1,000 example and how monthly deposits change the story.
Calculator guides
Plain-English formulas, tables and examples for the searches people actually type — then a free tool to run your own numbers. Every guide matches a calculator on this site.
Showing 13–18 of 19 guides · Page 3
Retirement Calculator
How Much Do I Need to Retire? Nest Egg and the 4% Rule
A retirement sketch is savings grown to a target age, then a 4% withdrawal test. Here is the math and what it leaves out.
Tip Calculator
How to Calculate a Tip (15%, 18%, 20%)
A tip is a percentage of the bill. Here are the common US rates, a $80 example and how our tip calculator splits the total.
Loan Calculator
How to Calculate a Loan Payment
A fixed loan payment comes from principal, APR and months. Here is the formula, a 36-month example and when to use extra principal.
Mortgage Calculator
How Mortgage Payments Work (Principal and Interest)
A fixed mortgage payment is mostly interest at first. Here is the P&I formula, what taxes and insurance add, and how to model it.
BMI Calculator
How to Calculate BMI and What the Number Means
Body mass index is a screening ratio, not a diagnosis. Here is the formula, the adult chart and when BMI misleads.