Sources & methods

How calculators and converters are built

Our tools use standard formulas and conversion factors that you’ll find in textbooks and official references. Loan and mortgage calculators use the usual amortisation maths; percentage tools use the standard “percent of” and “percent change” expressions; unit converters use fixed conversion factors (e.g. metres to feet, pounds to kilograms) that align with internationally agreed definitions.

Where possible, calculations run entirely in your browser. We don’t send your numbers to our servers for the core maths—you type, the page updates, and the result is shown. That keeps things fast and private. The downside is we can’t offer custom or regulated advice; we’re just applying the same formulas you could look up elsewhere.

Rounding and display

We use full precision inside the calculation and then round for display so the numbers stay readable. For example, a currency result might be shown to two decimal places, while a unit conversion might show a few more digits when the values are small. We don’t truncate or round in a way that would change the meaning of the result for normal use—we aim for “what you’d expect” when you punch the same numbers into a calculator or spreadsheet.

If you need exact values for contracts or compliance, treat our output as a guide and confirm with the authoritative source or a professional. We’re not rounding to mislead; we’re rounding so the page stays usable.

Results are informational only

Nothing on Vastorae is legal, financial, tax, or medical advice. Our calculators and converters are there to help you explore numbers, compare options, or double-check your own working. They are not a substitute for a qualified professional or for reading the terms of a product you’re buying.

For example: a mortgage calculator gives you an estimate of principal and interest based on the numbers you enter. It doesn’t know your credit history, local taxes, or lender rules. A BMI or calorie tool gives you a rough category or estimate; it doesn’t replace a doctor or dietitian. Use the results as a starting point, and when it matters, get advice from someone who is authorised to give it.

References we follow

We don’t copy text from these sources; we use them to check our formulas, constants, and criteria so our tools stay accurate and consistent.

• NIST (National Institute of Standards and Technology) — We use NIST for unit definitions and conversion factors (length, mass, temperature, pressure, etc.). Their weights and measures and related publications are the basis for our metric–imperial and SI conversions.
• WCAG (Web Content Accessibility Guidelines) — For our contrast checker and any accessibility-related guidance, we align with WCAG (e.g. contrast ratios for AA/AAA). The official WCAG 2.1 quick reference is where those criteria are defined; we don’t reproduce them here.
• Standard financial and health formulas — Loan and mortgage maths follow the usual amortisation and present-value formulas. BMI uses the standard kg/m² definition; BMR/TDEE tools use widely used equations (e.g. Mifflin–St Jeor). We don’t invent new formulae; we implement ones you can verify in textbooks or regulator guidance.

If you need the exact wording of a standard or the latest update to a constant, go to the source. We update our tools when we’re aware of changes, but we can’t guarantee we reflect every amendment the day it’s published.

Questions or corrections

If you think we’ve got a formula or conversion wrong, or you want to know which reference we used for a specific tool, please get in touch. We’re happy to clarify and to fix errors. For formal or high-stakes use, always confirm with the primary reference or a qualified professional.