Everything you need to know about 40Calc — how it works, how we build our tools, and what to do if something goes wrong.
Is 40Calc completely free to use?
Yes — all 40+ tools are permanently free. No premium tier, no hidden charges, no credit card required. Ever.
Do I need to create an account?
No account, no email, no signup of any kind. Open a tool and start calculating immediately — nothing to fill out.
How accurate are the calculations?
Every formula is verified against textbooks, academic sources, and professional standards. We achieve 99.9% accuracy across all tools. For critical financial or medical decisions, always confirm with a qualified professional.
Do the tools work on mobile?
Yes — every tool is designed mobile-first and tested on iOS and Android. The inputs are sized for touch, the layout adapts to small screens, and everything is keyboard accessible.
Can I use 40Calc offline?
Once a tool page loads, most calculators run entirely in your browser without any network connection. If you lose internet mid-calculation, your results aren’t affected.
Is my data private and secure?
Completely. All calculations happen locally in your browser. We don’t transmit, store, or log any of the numbers you enter. No cookies track your usage, and we have no advertising partnerships that profile users.
What types of calculators are available?
Finance (compound interest, loan EMI, ROI), Math (percentage, algebra, geometry), Health (BMI, calorie, age), Text (word counter, case converter), Date & Time, Color, Developer tools, and Unit Converters — 40+ total.
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