Who publishes and reviews the calculators
CalcLogicHub publishes the calculator pages as product documentation. The site-level organization is the named author and reviewer because formulas, interface labels, examples, and test cases are maintained together rather than attributed to an outside professional. A technical review does not mean a calculator provides financial, medical, legal, or other professional advice.
Latest site-wide technical review: September 2, 2026. Calculator pages show this date only after their displayed formula, worked example, output labels, cited sources, and relevant automated tests have been checked.
Formula selection
Each calculator states its formula beside the interactive result. We use standard mathematical definitions, fixed unit relationships, and conventional fixed-rate amortization methods. Worked examples make the inputs, substitutions, and expected output inspectable without relying on hidden server logic.
Reference standards
Where an external standard or public authority is relevant, the calculator page links directly to that source. Core references currently include:
- CDC — Calculating BMI
- Consumer Financial Protection Bureau — How mortgage amortization works
- Investor.gov — Compound Interest Calculator
- NIST Guide to the SI — Conversion Factors
Precision and rounding
Calculations retain full available numeric precision internally and round values for readable display. A displayed result can therefore differ slightly from a value rounded at every intermediate step. Unit converters identify important distinctions such as US liquid gallons versus imperial gallons.
Most unit conversions display up to six decimal places, temperature conversions up to four, and financial estimates and BMI up to two. A rounded display is not a statement about measurement accuracy. Convert using the original measured value and round only when your use case requires it.
Calendar rules
Date Difference returns the absolute elapsed-day count, while Days Until preserves the sign of the target date minus the starting date. Both use UTC midnight for entered calendar dates, so daylight-saving changes do not create partial days. An empty optional date uses the current date on the visitor's device. Counts include weekends and holidays and do not include both endpoints as whole days.
Age uses completed years, not days divided by 365. For February 29 births, this implementation reaches the next completed year on March 1 in a non-leap year. This convention is not a determination of legal age in a particular jurisdiction.
Validation and testing
The shared calculation engine is tested with a normal case for every calculator plus empty, invalid, zero, negative, decimal, boundary, and overflow cases. Calculator-specific constraints validate supported inputs. Temperature converters accept mathematical readings below absolute zero; they do not assess physical feasibility. Test results are checked before the formula review date is updated.
Explanations updated: . Calculator pages distinguish their explanation update from the earlier formula review date. Quick answers, examples, and unit assumptions describe the actual tool behavior and are available as page text before a visitor enters values.
Limits of the results
Advanced finance planners
The repayment planner uses a fixed monthly rate, end-of-month payments, and constant extra principal beginning in month one. The installment uses a numerically stable equivalent of the amortization formula; the last installment clears the remaining balance without overpayment. The monthly savings planner compounds monthly and adds deposits at the end of each month. Both support up to 1,200 whole months and retain internal precision instead of rounding every month to cents.
The planners run independently of the basic calculator inputs. They show their assumptions beside the form, provide comparisons or yearly summaries, and export all monthly rows into a CSV created locally in the browser. Tests reconcile repaid principal, zero and tiny rates, early payoff, recurring-deposit formulas, and invalid inputs. The guide library explains how to read those results. Published example buttons load fixed, illustrative inputs; all forty examples are validated against the engine during verification.
Finance results are educational estimates and do not include every fee, tax, insurance cost, lender rule, or investment risk. Health results are screening information, not medical advice or diagnosis. Important decisions should be checked independently with a qualified professional.
Corrections
If a formula, source, unit, label, or edge case appears incorrect, use the contact page and include the calculator URL, inputs, observed result, and expected result. Reproducible reports are reviewed against the displayed formula and test coverage. Review dates and sitemap modification dates are changed for substantive content, structured-data, formula, source, or navigation updates—not merely to make a page appear fresh.