BMI calculator
Go to the BMI calculator, pick metric or US units, and enter your height and weight. Click “Calculate BMI” to see your BMI and a rough category (underweight/normal/overweight/obese).
This uses the standard adult BMI formula only — it doesn’t account for age, sex, muscle mass or medical history. Always point people back to real medical professionals for anything health‑related.
Age calculator
On the Age calculator, choose your date of birth. The “as of” date defaults to today, but you can set it to a date in the past or future (for age on a specific date). The tool shows your age in years, and a breakdown in years, months and days.
Grade calculator
In the Grade calculator, each row is an assignment or test.
- Score = points you earned.
- Out of = maximum points.
- Weight % is optional. If you leave all weights blank, it just uses total points.
If any weights are filled in, the calculator uses a weighted average: percentage on each item times its weight, divided by the sum of weights. Output is a percentage and a rough A–F letter grade. Tell users to check their syllabus for the real grading rules.
Slope calculator
The Slope calculator takes two points (x₁, y₁) and (x₂, y₂).
It uses the standard formula (y₂ − y₁) ÷ (x₂ − x₁).
If the x‑values are the same, the line is vertical and the tool reports an undefined slope and the equation
x = constant. It also shows the line equation in the form y = mx + b for quick homework checks.
Tip calculator
On the Tip calculator, enter the bill, pick or type a tip percentage, and set the number of people. The tool shows:
- Tip amount
- Total bill (bill + tip)
- Per‑person amount
It doesn’t know local tipping customs; it’s just doing the math. The currency symbol box is cosmetic only.
Car loan calculator
The Car loan calculator uses the standard amortisation formula for fixed‑rate loans. Users enter price, down payment, APR, term in years and (optionally) an extra monthly payment.
The tool calculates an estimated monthly payment, total paid over the life of the loan and total interest. It ignores taxes, fees and credit‑specific adjustments, so you should keep disclaimers about this being “just a rough estimate” and “not financial advice”.
House affordability calculator
On the How much house can I afford? page, users plug in:
- Gross monthly income and other monthly debts
- Front‑end and back‑end debt‑to‑income ratios (defaults to 28% / 36%)
- Estimated monthly taxes + insurance + HOA
- Mortgage rate, term and planned down payment
The calculator:
- Computes the maximum monthly housing budget under those ratios.
- Subtracts taxes/insurance/HOA to get a max principal+interest payment.
- Backs into an approximate loan size using the standard payment formula.
- Adds the down payment to show a rough maximum home price.
This is extremely approximate; it’s just for planning. The page already flags that it’s not lending or financial advice and that real approval depends on a lender.