Quick answer: pick a calculator below – each one gives a live answer as you type, shows the formula it uses and lets you copy the result. They work on phones and computers, in any currency, and keep working offline once the page has loaded. Nothing is uploaded, so salaries, loans and health numbers stay private.
Calculators that show their working
A number on its own is hard to trust. Every calculator here tells you which formula it uses – the loan EMI formula, Mifflin-St Jeor for calories, I = P × R × T for simple interest – and most show a worked example on the page, so you can check the result by hand or explain it to someone else.
Built for the questions people actually ask
- Money: what will this loan cost me each month, how much interest will my savings earn, how much zakat do I owe, what is this hourly rate as a salary?
- Shopping and business: what is 30% off plus an extra 10%, how do I take VAT out of a price, what margin am I really making?
- Study: what is my GPA this semester, how do I convert CGPA to a percentage, how do I add fractions?
- Health: is my BMI in the healthy range, how many calories do I need?
- Time: how many hours did I work, how old am I in days, what date is 90 days from now?
Private by design
Many calculator sites send what you type to their servers or fill the page with trackers. These calculators are plain JavaScript running on your own device – the same approach as CleanPDF’s PDF and image tools. There is nothing to sign up for and no limit on how often you use them.
How to use CleanPDF calculators
- Pick a calculator. Choose from the groups above or use the site search.
- Type your numbers. Results update as you type; switch units or currency where offered.
- Check the working. Each result shows the formula and, where useful, a table or chart.
- Copy or reset. Copy the result into a message or document, or reset to start again.
Frequently asked questions
Are these calculators free?
Yes. All of them are free with no sign-up and no usage limit.
Do the calculators work offline?
Yes. Once a calculator page has loaded, it keeps working without an internet connection.
Is my data saved or sent anywhere?
No. All calculations run in your browser; nothing you type is sent to a server or stored.
Can I use my own currency?
Yes. Money calculators offer 27 currencies and pick a likely one from your browser language.
How accurate are the results?
They use standard published formulas and full floating-point precision, rounded only for display. For legal, tax, medical or religious decisions, confirm with a qualified professional.
Can I use the calculators on my phone?
Yes. Every calculator is designed for small screens first and also works inside the CleanPDF Android app.