Frequently Asked Questions

Find answers to common questions about our calculators.

General Questions

Yes! All calculators on OmniCalculator Pro are 100% free. No signup required, no subscription fees, no hidden costs. Just free, accurate calculators available anytime.

Our calculators use standard mathematical formulas and are thoroughly tested for accuracy. They're suitable for everyday use, education, and general business purposes. For critical financial or medical decisions, please consult with appropriate professionals.

No. All calculations happen locally in your web browser. We don't collect, store, or transmit any of your input data. Your calculations are completely private.

Absolutely! Our website is fully responsive and optimized for mobile devices. All calculators work perfectly on smartphones, tablets, and desktop computers.

No account needed! Just visit any calculator page and start calculating immediately. We believe tools should be accessible without barriers.

Calculator-Specific Questions

We use the standard BMI formula: BMI = weight (kg) / height² (m²). For imperial units (pounds and feet/inches), we convert to metric before calculating. The result is the same as any standard BMI calculator.

We use the Mifflin-St Jeor equation, which is considered the most accurate for estimating Basal Metabolic Rate. The formula accounts for age, gender, height, and weight.

Percentage change = ((New Value - Original Value) / Original Value) × 100. A positive result indicates an increase; negative indicates a decrease.

Margin is profit as a percentage of selling price (profit ÷ revenue). Markup is profit as a percentage of cost (profit ÷ cost). Same profit, different percentages. Our Profit Margin Calculator calculates both.

Technical Questions

Make sure you've entered valid numbers in all required fields. Check that you haven't accidentally included letters or special characters. If problems persist, try refreshing the page or using a different browser.

Yes! We love hearing from users. Visit our contact page to submit your suggestions. We prioritize calculators based on user demand and search volume.

Currently, we're a web-only platform. The good news is our website works great on mobile browsers — just bookmark omnicalculator.pro for quick access anytime!

Still Have Questions?

Can't find what you're looking for? Contact us and we'll be happy to help!

About This Site

These are the questions we are asked most often about how OmniCalculator Pro works, where our formulas come from, and what our results can reasonably be used for. Each individual calculator page also carries its own frequently asked questions covering that specific tool.

Frequently Asked Questions

Yes, every calculator is completely free with no signup, no account and no usage limits. The site is funded by advertising, which covers hosting and development so the tools can stay free for everyone.
No. All calculations run entirely in your browser using JavaScript. Nothing you type is sent to our servers or stored anywhere. When you close the page, the figures are gone. We could not retrieve your inputs even if we wanted to, because they never leave your device.
Every formula is verified against its published source and tested with known values before the calculator is published. That said, accuracy depends on the method itself. Financial projections rest on assumed returns that nobody can guarantee, and health formulas such as BMI are population screening tools rather than individual measurements. Each page states the limitations of its method.
From primary sources: government agencies, standards bodies, published clinical guidance and peer-reviewed research. Each calculator page lists the specific references used, so you can check the underlying source rather than taking our word for it.
Our tools are educational and produce estimates. They are not a substitute for professional advice, and we would not recommend relying on them for filings, medical decisions or legally binding calculations. Use them to understand a situation, then confirm anything consequential with a qualified professional.
Usually because a different formula or set of assumptions is being used. Ideal weight has four competing formulas that disagree by several kilograms; BMR has three; tax estimates depend on which deductions are assumed. Our pages state which method we use, so you can see exactly where a difference comes from.
Yes. Every calculator is built to work on phones, tablets and desktop browsers. Because the calculations run locally rather than on a server, they also work on slow connections.
Pages carry a last-reviewed date. We revise content when the underlying facts change, such as tax rates, health guidance or measurement standards, and when readers report errors. Corrections to calculations are made as soon as they are verified.
Please do. A good number of the tools on this site began as reader suggestions. Tell us what you want to calculate and what you would use it for through our contact page, and it goes on the list.
Email us through the contact page with the page name, the figures you entered, and the result you expected. Calculation errors are prioritised because they affect everyone using that tool. We verify against the source formula and correct the page if needed.

Understanding Our Results

Every calculator on this site produces an estimate based on a defined method. That method is stated on the page, along with its formula and its limitations. This matters because two calculators using different but equally legitimate methods will give different answers, and neither is wrong.

Ideal weight is a clear example. Four established formulas exist, they were developed for different purposes in different decades, and they disagree by several kilograms for the same person. Rather than picking one and presenting it as the answer, we show the spread, because the spread is the honest result.

Estimates versus measurements

A calculator applies a formula to the numbers you give it. It cannot observe your actual circumstances. A BMR equation estimates within roughly ten percent of a measured value; an investment projection assumes a return that markets do not guarantee. Treat every output as a well-founded starting point, not a measurement.

Privacy in Practice

Our calculators run in your browser. Nothing you enter is transmitted or stored, which is a deliberate design decision rather than a policy promise. It means the site cannot see your salary, your weight or your loan balance, because those figures never leave your device.

The site does use analytics to understand aggregate traffic patterns, and it displays advertising to fund free access. Both are described in our privacy policy. Neither has access to what you type into a calculator.

Still Have a Question?

If your question is not covered here or on the relevant calculator page, please contact us. Questions that come up repeatedly usually end up improving a page, so asking genuinely helps.