42 Terms
Calculator Glossary
Clear definitions of the concepts behind every CalcIntel calculator, the financial formulas underwriters use, the clinical equations dietitians rely on, the engineering constants from NIST and the EPA. Each entry links to the relevant calculators and the authoritative source where applicable.
Finance
Amortization
The process of paying off a debt with regular, equal payments over a scheduled term. Each payment covers both interest on the remaining bala...
Updated 2025-09-14
Compound Interest
Interest calculated on both the principal and the accumulated interest from previous periods. The formula A = P(1 + r/n)^(nt) shows how prin...
Updated 2025-08-22
APR vs. APY
APR (Annual Percentage Rate) is the simple annualized interest rate on a loan, excluding the effect of compounding. APY (Annual Percentage Y...
Updated 2025-10-03
Debt-to-Income Ratio (DTI)
The percentage of your gross monthly income that goes to minimum debt payments. Mortgage underwriters use DTI as the primary affordability g...
Updated 2025-11-11
Roth vs. Traditional IRA
A traditional IRA takes pre-tax contributions and taxes withdrawals in retirement. A Roth IRA takes after-tax contributions and makes qualif...
Updated 2026-01-18
Capitalization Rate (Cap Rate)
The ratio of a rental property's annual net operating income (NOI) to its purchase price, expressed as a percentage. Cap rate = NOI ÷ Proper...
Updated 2025-07-29
FIRE Number
The investment balance required to retire and live on passive withdrawals, following the Financial Independence, Retire Early movement. The ...
Updated 2025-12-07
Marginal Tax Rate
The tax rate applied to your next dollar of income, determined by federal income tax brackets. The 2026 brackets for a single filer range fr...
Updated 2026-02-14
Private Mortgage Insurance (PMI)
Insurance required by most lenders when a conventional mortgage borrower puts less than 20% down. PMI protects the lender, not the borrower,...
Updated 2025-10-19
Break-Even Point
The sales volume at which total revenue equals total costs, producing zero profit. Break-even units = Fixed Costs ÷ (Price per Unit − Variab...
Updated 2025-11-26
Health & Nutrition
Body Mass Index (BMI)
A screening metric that divides weight in kilograms by height in meters squared (kg/m²). The World Health Organization classifies adults as ...
Updated 2025-09-02
Basal Metabolic Rate (BMR)
The number of calories your body burns at complete rest to maintain essential functions, breathing, circulation, cell production, and body t...
Updated 2025-10-28
Total Daily Energy Expenditure (TDEE)
The total calories you burn in a typical day, including BMR plus energy spent on movement, digestion, and exercise. TDEE = BMR × activity mu...
Updated 2026-03-04
Macronutrients
The three energy-providing nutrient categories: protein (4 calories per gram), carbohydrates (4 calories per gram), and fat (9 calories per ...
Updated 2025-11-18
Body Fat Percentage
The share of total body weight made up of fat tissue, as opposed to muscle, bone, water, and organs. The American Council on Exercise classi...
Updated 2025-08-06
One-Rep Max (1RM)
The maximum weight you can lift once with proper form on a given exercise. Because testing a true 1RM is risky without a spotter, coaches us...
Updated 2025-09-23
Heart Rate Zones
Percentage ranges of your maximum heart rate, each producing a distinct training effect. Max HR is commonly estimated as 220 minus your age,...
Updated 2026-01-09
VO2 Max
The maximum volume of oxygen your body can use during intense exercise, measured in milliliters per kilogram per minute (mL/kg/min). VO2 max...
Updated 2025-10-15
Math & Statistics
Percentage Change
The relative difference between an old value and a new value, expressed as a percentage. The formula is ((New − Old) ÷ Old) × 100. If stock ...
Updated 2025-07-11
Standard Deviation
A measure of how spread out a dataset is around its mean, expressed in the same units as the data. For a normal distribution, about 68% of v...
Updated 2025-11-04
Pythagorean Theorem
For any right triangle, the square of the hypotenuse equals the sum of squares of the other two sides: a² + b² = c². Named for the Greek mat...
Updated 2025-08-27
Quadratic Formula
The closed-form solution for any quadratic equation ax² + bx + c = 0, where a ≠ 0: x = (−b ± √(b² − 4ac)) ÷ 2a. The discriminant b² − 4ac de...
Updated 2025-09-30
Mean, Median, and Mode
Three measures of central tendency. The mean is the arithmetic average (sum ÷ count). The median is the middle value when the data is sorted...
Updated 2026-02-02
Construction & Home
Cubic Yard
A unit of volume equal to 27 cubic feet (3 ft × 3 ft × 3 ft), the standard measure for concrete, mulch, topsoil, and gravel in the United St...
Updated 2025-10-11
Roofing Square
A unit of roof area equal to 100 square feet, used by roofing contractors for material ordering and bidding. A 2,400 square foot roof is 24 ...
Updated 2025-09-08
Paint Coverage
The area a gallon of paint covers in a single coat, typically 350-400 square feet on smooth, primed drywall. Textured walls, porous surfaces...
Updated 2025-11-22
British Thermal Unit (BTU)
The energy needed to raise one pound of water by one degree Fahrenheit, used in HVAC sizing. Heating and cooling loads are typically express...
Updated 2025-08-14
Wire Gauge (AWG)
The American Wire Gauge standard for electrical conductor diameter. Lower numbers mean thicker wire and higher current capacity. The Nationa...
Updated 2025-07-21
R-Value
A measure of thermal resistance for insulation materials. Higher R-values mean better insulating performance. The Department of Energy recom...
Updated 2026-01-25
Science & Energy
Ohm's Law
The fundamental relationship in electrical circuits: V = I × R, where voltage (V) equals current (I) times resistance (R). Power dissipation...
Updated 2025-08-04
Peak Sun Hours
The equivalent number of hours per day when solar radiation averages 1,000 watts per square meter, the standard test condition for solar pan...
Updated 2025-12-16
Kinetic Energy
The energy of a moving object, calculated as ½mv² where m is mass and v is velocity. Because velocity is squared, doubling speed quadruples ...
Updated 2025-10-07
Ideal Gas Law
PV = nRT, relating pressure (P), volume (V), moles of gas (n), the universal gas constant (R = 8.314 J/mol·K), and temperature in Kelvin (T)...
Updated 2025-09-19
Half-Life
The time required for half of a radioactive substance to decay. The remaining fraction follows N(t) = N₀ × (1/2)^(t/t½). Carbon-14's 5,730-y...
Updated 2025-11-13
Carbon Footprint
The total greenhouse gas emissions caused directly and indirectly by a person, organization, event, or product, expressed as tons of CO₂ equ...
Updated 2026-02-24
Everyday Life
Tip Etiquette
Customary gratuity rates in the United States vary by service type. Sit-down restaurants: 15% for adequate service, 18% for good, 20%+ for e...
Updated 2025-07-18
Unit Price
The cost per standard unit of measurement, per ounce, per pound, per sheet, per liter, used to compare products across different package siz...
Updated 2025-10-23
Gas Mileage (MPG)
Miles traveled per gallon of fuel consumed. Calculate by resetting your trip odometer at a full tank, driving normally, and dividing miles t...
Updated 2025-12-29
Kilowatt-Hour (kWh)
The standard unit of electric energy billing: one kilowatt of power used for one hour. Residential kWh rates range from about $0.10 in low-c...
Updated 2026-03-11
Dog Years
The old rule that one dog year equals seven human years is a myth. Modern veterinary research, including a 2019 epigenetic clock study from ...
Updated 2025-08-31
Time Zones
Geographic regions observing a common standard time, typically offset from Coordinated Universal Time (UTC) by whole or half-hour increments...
Updated 2025-11-02
Inflation Rate
The annual percentage change in a price index, most commonly the Consumer Price Index (CPI-U) published monthly by the Bureau of Labor Stati...
Updated 2026-01-31