Data Sources & Attribution

ClickSolveTools calculators, converters, and reference tools rely on publicly available government data, peer-reviewed scientific formulas, and international standards. This page lists the primary sources behind the numbers, formulas, and reference data used across our tools.

Government & Public Data

U.S. Internal Revenue Service (IRS) Public Domain

Federal income tax brackets, standard deductions, FICA rates (Social Security 6.2%, Medicare 1.45%), self-employment tax (SECA) rates, and IRS Publication 15 withholding tables. Used in: Tax Bracket Calculator, Paycheck Calculator, Self-Employment Tax Calculator.

IRS Publication 15 Self-Employment Tax

U.S. Bureau of Labor Statistics (BLS) Public Domain

Consumer Price Index (CPI-U) historical data used for inflation calculations and purchasing-power adjustments. Used in: Inflation Calculator.

CPI Home CPI Data Tables

U.S. Social Security Administration (SSA) Public Domain

Social Security wage base limits and full retirement age guidelines.

Wage Base & COLA

U.S. Census Bureau Public Domain

State-level demographic and statistical reference data used for general public-data lookups.

Census Data

U.S. State Tax Authorities Public Domain

State income-tax brackets and sales-tax base rates published by each state's Department of Revenue or equivalent agency. Local taxes (city, county, district) vary and are not included; rates shown are approximate base rates.

Published Scientific Formulas

Body Mass Index (BMI) Classification WHO

BMI thresholds (underweight < 18.5, normal 18.5–24.9, overweight 25–29.9, obese ≥ 30) per the World Health Organization. Used in: BMI Calculator, Ideal Weight Calculator.

WHO Obesity Topic

Mifflin-St Jeor Equation (BMR / Calories) Peer-reviewed

Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990;51(2):241-7. Used in: Calorie Calculator, Calorie Burn Calculator, Weight Loss Calculator.

Harris-Benedict Equation (Original BMR) Peer-reviewed

Harris JA, Benedict FG. A Biometric Study of Basal Metabolism in Man. Carnegie Institution of Washington, 1919. Provided as a comparison option alongside Mifflin-St Jeor.

U.S. Navy Body Fat Method Peer-reviewed

Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, 1984. Used in: Body Fat Calculator.

Widmark Formula (Blood Alcohol) Peer-reviewed

Widmark EMP. Die theoretischen Grundlagen und die praktische Verwendbarkeit der gerichtlich-medizinischen Alkoholbestimmung. Berlin: Urban & Schwarzenberg, 1932. Used in: Alcohol Units Calculator. Estimates only — never use to determine driving fitness.

One-Rep Max Formulas (Epley / Brzycki / Lombardi) Peer-reviewed

Epley B (1985), Brzycki M (1993, JOPERD), Lombardi VP (1989). Used in: One-Rep Max Calculator.

Ideal Body Weight Formulas Peer-reviewed

Devine BJ (1974), Robinson JD et al. (1983), Miller DR et al. (1983), Hamwi GJ (1964). Used in: Ideal Weight Calculator.

Lean Body Mass Formulas Peer-reviewed

Boer P (1984), James WPT (1976), Hume R (1966). Used in: Lean Body Mass Calculator.

Maximum Heart Rate (220 − age) and Karvonen Method Peer-reviewed

Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae, 1957;35(3):307-15. Used in: Heart Rate Zones.

Naegele's Rule (Pregnancy Due Date) Clinical Standard

Estimated due date = first day of last menstrual period + 280 days (40 weeks). Attributed to Franz Karl Naegele, 1812. Used in: Pregnancy Due Date Calculator, Ovulation Calculator.

Riegel Race-Time Prediction Formula Peer-reviewed

Riegel PS. Time predicting. Runner's World, 1977. Used in: Marathon Pace Calculator.

Wishnofsky's Rule (3,500 kcal ≈ 1 lb fat) Peer-reviewed

Wishnofsky M. Caloric equivalents of gained or lost weight. American Journal of Clinical Nutrition, 1958;6(5):542-6. Used in: Weight Loss Calculator.

Sleep Cycle Duration (~90 minutes) Peer-reviewed

Dement W, Kleitman N. Cyclic variations in EEG during sleep and their relation to eye movements, body motility, and dreaming. Electroencephalography and Clinical Neurophysiology, 1957;9(4):673-90. Used in: Sleep Calculator.

Flesch-Kincaid Readability Peer-reviewed

Flesch R (1948); Kincaid JP, Fishburne RP, Rogers RL, Chissom BS (1975). Used in: Readability tools.

Industry Standards

ISO 216 (Paper Sizes) ISO Standard

International standard defining the A, B, and C series paper sizes (e.g., A4 = 210 × 297 mm). Used in: Paper Size Reference and any tool that references metric paper sizes.

Unicode Consortium Unicode Standard

Unicode character data, code points, names, and emoji definitions (Unicode Standard, latest version). Emoji shortcodes follow CLDR annotations.

Unicode Emoji List

NATO Phonetic Alphabet (ICAO Spelling Alphabet) ICAO / ITU

Alpha, Bravo, Charlie… spelling alphabet adopted by the International Civil Aviation Organization (1956) and used by NATO and ITU. Used in: Phonetic Alphabet Translator.

International System of Units (SI) BIPM

Base and derived units, prefixes, and conversion factors per the Bureau International des Poids et Mesures (BIPM). Used across length, mass, volume, temperature, pressure, energy, and other unit converters.

IANA Time Zone Database (tzdata) Public Domain

Time-zone definitions and historical UTC offsets via the browser's built-in Intl/Date APIs, which use the IANA tz database.

Industry Size Conventions (Shoes, Rings, Clothing, Bras) Approximate

Conversions between US, UK, EU, JP, and other regional sizing systems are based on widely published industry tables. Sizing varies by brand and manufacturer; results are approximate. Always check the brand's official size chart before purchasing.

Quotes, Word Lists & Reference Text

Quotation Sources Public Domain

Quotes used in the Random Quote Generator and similar tools are attributed to authors whose works are in the public domain (typically authors deceased before 1929 under U.S. copyright law) or are commonly attributed as anonymous. If you believe a quote is incorrectly attributed or should be removed, please contact [email protected].

Word Lists & Dictionaries Factual / Public Domain

Word lists used by random word, password phrase, name picker, and similar generators are compiled from common-use English vocabulary, public-domain word lists, and standard dictionary entries. Individual words and short factual lists are not protected by copyright.

Open-Source Libraries

Third-party JavaScript libraries (Tailwind CSS, math.js, pdf-lib, PDF.js, jsPDF, jsQR, JSZip, JsBarcode, marked, highlight.js, mammoth.js, lamejs, QRCode.js, js-yaml) are listed individually with their licenses and links on the Licenses page.

Disclaimer & Accuracy

All data is sourced from publicly available government publications, peer-reviewed research, and international standards. We make every effort to ensure accuracy but cannot guarantee that all data is current. Tax brackets, contribution limits, exchange rates, and similar figures change over time and may not reflect the most recent updates. For the most current information, refer to the original sources linked above. Always verify results independently when accuracy is critical, and consult a qualified professional for financial, medical, or legal decisions.

Corrections

If you spot a missing source, an outdated reference, or a citation error on this page or in any of our tools, please email [email protected] and we'll review and update promptly.