Free tools for everyday questions

CuriosityTools is a free collection of calculators and interactive world maps for the questions that come up in daily life. How much should I tip? What will this loan really cost? How old is someone, exactly? How does my country compare with the rest of the world? Every tool works in your browser, with no sign-up and no app to install, and each one comes with a plain-English guide that explains how the answer is worked out.

Calculators

Money and investing

• Compound Interest Calculator – see how savings and regular contributions grow over time.
• Loan Calculator – monthly payments, total interest, and a full payoff schedule for car, personal, and student loans.
• Mortgage Calculator – the true monthly cost of a home, including property tax, insurance, and HOA fees.
• Tip Calculator – work out the tip and split the bill in seconds.
• Discount Calculator – sale prices, stacked discounts, and sales tax, in dollars or won.
• Stock Fair Value Calculator – compare a U.S. stock’s price with a cash-flow-based estimate built from SEC filings.

Health

• BMI Calculator – body mass index in US or metric units, with the standard adult categories.
• Calorie Calculator – estimate your resting energy use and daily maintenance calories.

Math and everyday life

• Calculator – a clean everyday calculator with backspace and keyboard support.
• Percentage Calculator – percent of a number, percentage change, increases, decreases, and more.
• Graphing Calculator – plot up to three functions and explore them by zooming and dragging.
• Age Calculator – exact age in years, months, and days, plus your next birthday.
• D-Day & Date Calculator – days between dates, D-day countdowns, and 100-day anniversaries.
• Conversion Calculator – length, weight, temperature, volume, area, speed, time, and digital data.
• Pyeong Converter – Korean pyeong (평) to square meters and square feet, with typical apartment sizes.

World maps and data explorers

Our interactive maps turn official statistics into pictures you can explore. Choose a topic, click any country, and compare it with the rest of the world.

• World Explorer – capitals, population, currencies, languages, and time zones for every country.
• Population Explorer – growth, age structure, density, urbanization, and life expectancy.
• Time Zone Explorer – the current local time and UTC offset anywhere in the world.
• Economic Explorer – GDP, income per person, growth, inflation, and unemployment.
• Trade Explorer – exports, imports, and how open each economy is to trade.
• Development & Living Standards Explorer – poverty, inequality, internet access, electricity, and sanitation.
• Health Explorer – life expectancy, child health, doctors, and health spending.
• Education Explorer – literacy, school and university enrollment, and education spending.
• Climate & Weather Explorer – current weather and a 5-day forecast for cities worldwide.
• Energy Explorer – energy use, renewables, and access to electricity.
• Environment Explorer – carbon emissions, forests, air quality, and clean water.
• Agriculture & Food Explorer – farmland, crop yields, farm jobs, and food security.

How we build our tools

• Transparent formulas. Every calculator shows or explains the formula it uses, with worked examples you can check by hand.
• Trusted public data. Our maps use official sources such as the World Bank’s World Development Indicators, the U.S. Securities and Exchange Commission (SEC), and Open-Meteo weather data, and we show the year each figure refers to.
• No sign-up needed. Most calculations run right in your browser, and you never need an account to use a tool. See our Privacy Policy for details.
• Built for phones. Every tool works on a phone, tablet, or computer.

Our tools are for education and general information. They are not a substitute for professional financial, medical, or legal advice. See our Financial Disclaimer and Terms of Use, and contact us if you spot an error or have an idea for a new tool.