Simple tools for everyday numbers
Free, private calculators for finance, health, math, and everyday life — each one paired with a plain-language explainer. Nothing to install, nothing to sign up for.
27 tools
- Finance
Compound Interest Calculator
See how an initial balance and regular contributions grow over time with compounding.
- Finance
Loan Payment Calculator
Estimate the monthly payment and total interest on a fixed-rate loan.
- Finance
Mortgage Calculator
Estimate your monthly mortgage payment with taxes and insurance, plus an amortization chart.
- Finance
Sales Tax Calculator
Add sales tax to a price and see the total and tax amount.
- Finance
Salary Calculator
Convert an hourly wage into weekly, monthly, and annual pay.
- Finance
Auto Loan Calculator
Estimate a car loan payment including sales tax, down payment, and trade-in.
- Finance
Savings Goal Calculator
Find the monthly amount to save to reach a target by a chosen date.
- Finance
ROI Calculator
Calculate return on investment, net gain, and annualized return.
- Finance
Markup & Margin Calculator
Turn cost and price into profit, margin, and markup percentages.
- Finance
Break-Even Calculator
Find the number of units you need to sell to cover fixed and variable costs.
- Health
BMI Calculator
Calculate body mass index from height and weight in metric or imperial units.
- Health
Calorie (BMR/TDEE) Calculator
Estimate your resting and daily calorie needs from your body stats and activity level.
- Health
Calories Burned Calculator
Estimate calories burned for an activity from your weight and duration.
- Health
Ideal Weight Calculator
Estimate a healthy target weight for your height using the Devine formula.
- Math
Percentage Change Calculator
Find the percentage increase or decrease between two numbers.
- Math
Percentage Calculator
Work out what a percent of a number is, or increase/decrease a number by a percent.
- Everyday
Tip & Bill Splitter
Split a bill and tip evenly across any number of people.
- Everyday
Discount Calculator
Find the sale price and how much you save at any percentage off.
- Everyday
Age Calculator
Work out your exact age in years, months, and days from your birth date.
- Everyday
Date Difference Calculator
Count the days, weeks, months, and years between two dates.
- Everyday
Fuel Cost Calculator
Estimate the fuel cost of a trip from distance, MPG, and gas price.
- Everyday
Gas Mileage (MPG) Calculator
Work out your car's fuel economy in MPG, L/100km, and km per liter.
- Everyday
Commute Cost Calculator
See what your commute costs in gas per day, week, month, and year.
- Everyday
Gas Trip Cost Splitter
Split a road trip's gas cost evenly across everyone in the car.
- Everyday
Square Footage Calculator
Calculate the area and perimeter of a room from its length and width.
- Everyday
Rent Affordability Calculator
See how much rent you can afford based on your income.
- Everyday
Unit Converter
Convert between common length, weight, and temperature units.
Calculators that explain the answer
Most online calculators hand you a number and stop there. CalcJuice pairs every tool with a short, plain-language explainer — how the math works, a worked example with real figures, and the common mistakes to avoid — so you understand the result, not just read it. Everything runs in your browser, so your inputs never leave your device, and there’s nothing to install or sign up for.
What you’ll find here
- Finance — mortgage, auto and personal loans, compound interest, savings goals, ROI, sales tax, salary, markup and margin, and break-even, several with amortization charts.
- Health — BMI, calorie needs (BMR/TDEE), calories burned, and ideal weight, in metric or imperial units.
- Math — percentages and percentage change, for the everyday calculations that come up more often than any other.
- Everyday — tip splitting, discounts, unit and gas conversions, commute and fuel cost, date differences, age, square footage, and rent affordability.
New calculators are added regularly. Use the search and category filters above to find the one you need, or browse the full list — each tool is free, fast, and works on any device.