FreeTools Labs Glossary
Knowledge behind our tools
Understand how our calculators and planners work, which methods they use, and how to put their results into context.
What is the glossary?
Our tools provide results. The glossary explains the basics, inputs and calculation steps behind them.
It makes methods, assumptions and limitations transparent, then points you to useful tools and related topics.
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40 articles found
Body and health
Age and age calculation
Learn how calendar age is worked out from a birth date and reference date in years, months and days, including leap years and uneven months.
Read article →Everyday, technology and maths
Battery runtime
Understand how capacity, voltage, load and efficiency relate to runtime, and why a theoretical battery estimate can differ in use.
Read article →Body and health
Understanding BMI
Learn how BMI relates weight to height, how values are classified, and why it does not directly measure body fat.
Read article →Body and health
Body metrics and body fat
Explore different body-metrics models and learn why their inputs and methods can produce different estimates.
Read article →Everyday, technology and maths
Buying, renting and leasing
Learn how up-front costs, recurring payments, financing and residual value change a comparison over its chosen term. Monthly payments alone do not tell the whole story.
Read article →Nutrition
Calories and energy needs
Learn how resting energy, body data and activity factors lead to estimated energy needs and a goal range. The article puts the model assumptions and limits into context.
Read article →Everyday, technology and maths
Chemical calculations
Learn how chemical formulas, molar mass, amount of substance and concentration relate, from conversions to dilution and density.
Read article →Everyday, technology and maths
Concrete volume and materials
Learn how dimensions become a geometric volume and then a practical concrete quantity. Allowance and bag demand help put an order quantity into context.
Read article →Everyday, technology and maths
Converting units
Learn how quantities, dimensions and conversion factors work together, and why temperature and other special cases need more than one fixed factor.
Read article →Everyday, technology and maths
Coordinate geometry
Learn how coordinates can be used to derive distances, midpoints, slopes, lines and other geometric relationships.
Read article →Body and health
Cycle and ovulation
Learn how period dates and cycle lengths create calendar forecasts for upcoming dates, and why ovulation and possible windows remain estimates.
Read article →Everyday, technology and maths
Dates, time and working hours
Learn how calendar and time differences are calculated, and why months, years and working spans cannot always be treated as fixed quantities.
Read article →Everyday, technology and maths
Electrical engineering basics
Learn how voltage, current, resistance and power relate, and how these relationships affect circuits and voltage drop.
Read article →Everyday, technology and maths
Electricity and energy costs
Learn why kW describes power and kWh describes energy, and how power, runtime and price produce estimated energy costs.
Read article →Everyday, technology and maths
Fractions and mixed numbers
Learn how fractions are built, how numerators and denominators work together, and why simplifying, expanding and common denominators matter.
Read article →Everyday, technology and maths
Fuel consumption and trip costs
Learn how distance, fuel consumption and fuel price combine into trip costs, and why l/100 km, km/l and mpg express consumption differently.
Read article →Everyday, technology and maths
Grades and weighted scoring
Learn how points, percentages and weights combine into an overall result, and why rules can vary between grading systems.
Read article →Everyday, technology and maths
Income tax basics
Learn how an income-tax model uses taxable income and rate logic, and why country, tax year and inputs determine the result.
Read article →Everyday, technology and maths
Inflation and purchasing power
Learn how inflation changes prices and purchasing power over time, and why nominal and real values need to be distinguished.
Read article →Everyday, technology and maths
Investing, interest and returns
Learn how interest, cash flows, time and fees affect measures such as present value and future value in financial models.
Read article →Everyday, technology and maths
IP addresses and subnets
Learn how IP addresses and prefixes structure networks, and how CIDR, subnet masks and address ranges relate.
Read article →Nutrition
Kitchen measures and ingredient conversion
Learn why kitchen measures cannot always be converted directly between volume and mass, and how ingredients and density affect the result.
Read article →Everyday, technology and maths
Loans, debt and financing
Learn how payments, interest, repayment and remaining balance relate, and how financing models can be compared mathematically.
Read article →Everyday, technology and maths
Margin, markup and profit
Learn how cost, selling price and profit relate, and why margin and markup use different percentage bases.
Read article →Everyday, technology and maths
Numbers, bases and divisors
Learn how numbers are represented in different bases and how place values, divisors, factors and prime numbers describe their structure.
Read article →Training and performance
1RM and maximal strength
Learn how a 1RM is estimated from load and repetitions, why seven formulas can differ, and how RIR and RPE contribute.
Read article →Everyday, technology and maths
Secure passwords
Learn how length, character pool and random selection affect a password’s theoretical strength, and how the generator creates characters locally.
Read article →Everyday, technology and maths
Understanding percentages
Learn how base value, percentage value and percentage rate relate, and why percentage change differs from percentage points.
Read article →Body and health
Pregnancy dates and due dates
Learn how gestational age and estimated dates are calculated from different starting data, and why they remain estimates.
Read article →Nutrition
Protein needs
Learn how body weight, activity and goal context contribute to a model-based protein range and reference value.
Read article →Everyday, technology and maths
Randomness and random numbers
Learn how random numbers are produced within a range, how distribution matters, and why short sequences can look uneven.
Read article →Everyday, technology and maths
Retirement planning
Learn how starting capital, contributions, time, assumed returns, inflation and withdrawals interact in retirement-planning models.
Read article →Training and performance
Running, pace and times
Learn how pace, time, distance and speed relate, and how target times or splits are derived mathematically.
Read article →Everyday, technology and maths
Salary, hourly pay and overtime
Learn how hourly pay, working time and pay periods are converted mathematically, and how overtime contributes.
Read article →Everyday, technology and maths
Sales tax and VAT
Learn how net amount, tax amount and gross amount relate mathematically, and why extracting included tax differs from adding a rate to net.
Read article →Everyday, technology and maths
Scientific calculation
Learn how mathematical expressions are evaluated and how operators, functions and order of operations shape the result.
Read article →Everyday, technology and maths
Statistics, probability and analysis
Learn how statistical measures summarise data, reveal differences and why they always need context for interpretation.
Read article →Everyday, technology and maths
Splitting bills and tips
Learn how a bill, tip and shares are distributed into amounts per person, and why rounding matters for multiple people.
Read article →Training and performance
Understanding training plans
Learn how training goals, experience, available time and resources shape a structured plan, and why an automatically generated plan remains a starting point.
Read article →Body and health
Water intake reference values
Understand fixed DGE reference values for beverages, solid food, oxidation water and total water in an adult age group.
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