Calculators that show their work.
Most calculator sites hand you a number and hope you don't ask how they got it. calcgeeks does the opposite. Every tool here shows the exact formula it uses, walks through a worked example, and tells you where the math comes from — so you can trust the answer and learn something while you're at it.
Money & finance
Loan calculator
Monthly payment, total interest, and a full amortization schedule.
Mortgage calculator
Principal, interest, taxes and insurance in one monthly figure.
Compound interest
See how savings grow with regular contributions over time.
Savings goal calculator
How much to save monthly, or how long your goal will take.
Emergency fund calculator
Set your target and see how long it takes to fully fund it.
Percentage calculator
Percent of a number, change between two values, and more.
Tip calculator
Tip amount and an even split across the whole table.
Health & body
Dates & time
Money guides
How calcgeeks builds its calculators
Every calculator on this site is built around a published, verifiable formula — the same standard equations used by lenders, clinicians, and statisticians. We don't invent math, and we don't hide it. On each page you'll find the formula written out, a step-by-step example using real numbers, and a plain-language explanation of what the result actually means and where it can mislead you.
We're deliberate about boundaries, too. A loan estimate is not a loan offer; a BMI figure is a screening number, not a diagnosis; a due date is a 40-week estimate, not an appointment. Where a tool touches money, health, or law, you'll see a clear disclaimer and a pointer to the kind of professional who should make the real call. The goal isn't to replace your doctor, lender, or accountant — it's to help you walk into those conversations already understanding the numbers.
Who's behind calcgeeks
Analena Shull
After about 15 years working in finance, I kept meeting people tripped up by the same two things — budgeting their income, and understanding how the numbers behind their loans actually work. I built calcgeeks to help: calculators that show their work, and plain-English guides for everyday money decisions.