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Get in touch for questions, feedback or new calculator suggestions. Fill in the form below, or write to us directly — whichever you prefer.

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hello@oncehesap.com — we usually reply within 1–2 business days.

Are the calculations reliable? The formulas follow standard sources, but tax, interest and clinical reference values change over time. For important decisions, please consult a professional — see our Disclaimer.
Is my data stored? The values you enter are sent to our server to compute the result, but we do not save them and we never use them for advertising. Our Privacy Policy explains this in full.
Can I suggest a new calculator? Yes, please — use the form above and tell us what you need. Suggestions from visitors are where many of our tools come from.
Found a mistake? Tell us the calculator, the values you entered and the result you expected, and we will look into it.