Glossary

Finance terms

What does Amortisation mean?

Amortisation is paying off a loan in regular instalments that each cover the interest due and part of the balance, so the amount owed reaches zero by the end of the term. Early instalments are mostly interest; later ones are mostly balance.

Work it out with the Mortgage Repayment Calculator.

What does APR mean?

APR (annual percentage rate) is the yearly cost of borrowing shown as a percentage, including the interest and some compulsory fees, so one loan can be compared with another on the same basis.

Work it out with the Loan Repayment Calculator.

What does Compound interest mean?

Compound interest is interest earned on the original amount plus the interest already added, so the balance grows on itself. The more often interest is added, the faster it grows.

A = P × (1 + r/n)^(n × t)

Work it out with the Compound Interest Calculator.

What does Debt avalanche mean?

The debt avalanche method pays the minimum on every debt and puts all spare money on the debt with the highest interest rate first. It normally costs the least interest overall.

Work it out with the Debt Avalanche Calculator.

What does Debt snowball mean?

The debt snowball method pays the minimum on every debt and puts all spare money on the smallest balance first. It may cost more interest than the avalanche method, but clears whole debts sooner.

Work it out with the Debt Snowball Calculator.

What does Emergency fund mean?

An emergency fund is cash set aside for unexpected costs or a loss of income, usually measured in months of essential spending rather than a fixed sum.

Work it out with the Emergency Fund Calculator.

What does Gross pay mean?

Gross pay is what you earn before anything is taken off: before tax, National Insurance, pension contributions and student loan repayments.

Work it out with the Hourly to Salary Calculator.

What does Overpayment mean?

An overpayment is paying more than the required repayment, with the extra going to reduce the balance. It usually cuts the interest paid and shortens the term, subject to any limit or charge from the lender.

Work it out with the Mortgage Calculator with Extra Payments.

What does Principal mean?

The principal is the amount borrowed or invested, before any interest is added. On a loan it is the balance interest is charged on; on an investment it is the starting sum.

Work it out with the Loan Repayment Calculator.

What does Stamp Duty Land Tax (SDLT) mean?

Stamp Duty Land Tax is the tax paid when buying property or land in England and Northern Ireland. It is charged in bands, so each rate applies only to the part of the price that falls within that band.

Work it out with the Stamp Duty Calculator for England & Northern Ireland.

What does Student loan plan mean?

A student loan plan (Plan 1, 2, 4 or 5, or the Postgraduate Loan) sets the income threshold above which you start repaying and the rate you repay at. Which plan you are on depends on when and where you studied.

Work it out with the UK Student Loan Repayment Calculator.

What does Take-home pay mean?

Take-home pay, also called net pay, is what reaches your bank account after tax, National Insurance, pension contributions and any student loan repayments have been deducted from gross pay.

Work it out with the UK Take-Home Pay Calculator.

Health terms

What does BMI (body mass index) mean?

BMI is weight in kilograms divided by height in metres squared. It is a quick screening number for adults, not a diagnosis, because it cannot tell muscle from fat.

BMI = weight (kg) ÷ height (m)²

Work it out with the BMI Calculator.

What does BMR (basal metabolic rate) mean?

Basal metabolic rate is the energy your body uses at complete rest to keep you alive, in calories a day. Your daily needs are BMR plus the energy you use moving about.

Work it out with the BMR Calculator.

What does Body fat percentage mean?

Body fat percentage is the share of your total weight that is fat. Tape-measure methods such as the US Navy method estimate it from body measurements.

Work it out with the Body Fat Percentage Calculator.

What does Body surface area mean?

Body surface area is the total area of the skin, estimated from height and weight. Medicine uses it in some clinical measures, so several formulas exist; the figure here is for reference only, not for dosing.

Work it out with the Body Surface Area Formula Calculator.

What does Calorie deficit mean?

A calorie deficit means eating fewer calories than your body uses, which is what makes weight fall. A bigger deficit means faster loss but is harder to sustain.

Work it out with the Weight Loss Calorie Calculator.

What does Calorie surplus mean?

A calorie surplus means eating more calories than your body uses, which is what makes weight rise. A small surplus gains weight more gradually.

Work it out with the Weight Gain Calorie Calculator.

What does FFMI (fat-free mass index) mean?

The fat-free mass index is your fat-free mass divided by your height in metres squared, the way BMI treats total weight. It makes fat-free mass comparable between people of different heights.

Work it out with the Fat-Free Mass Index (FFMI) Calculator.

What does Ideal body weight mean?

Ideal body weight is an estimate of a weight for your height, from formulas such as Devine or Robinson. Different formulas give different answers, so it is a rough guide, not a target.

Work it out with the Ideal Body Weight (IBW) Formula Calculator.

What does Lean body mass mean?

Lean body mass is everything in your body that is not fat: muscle, bone, organs and water. Formulas can estimate it from height and weight, but they do not measure it.

Work it out with the Lean Body Mass Calculator.

What does Macronutrients mean?

Macronutrients (macros) are protein, carbohydrate and fat, the three nutrients that supply calories. A macro target splits your daily calories between them, in grams.

Work it out with the Macro Calculator.

What does Maintenance calories mean?

Maintenance calories are the calories a day you need to keep your weight steady. Eating less than this leads to weight loss and eating more leads to gain, on average.

Work it out with the Maintenance Calories Calculator.

What does Running pace mean?

Pace is the time taken to cover a set distance, usually minutes per kilometre or per mile. It is the reverse of speed: a lower pace figure means running faster.

pace = time ÷ distance

Work it out with the Running Pace Calculator.

What does Waist-to-height ratio mean?

Waist-to-height ratio is your waist circumference divided by your height, both in the same unit. It adjusts for how tall you are, which a waist measurement alone does not.

WHtR = waist ÷ height

Work it out with the Waist-to-Height Ratio Calculator.

What does Waist-to-hip ratio mean?

Waist-to-hip ratio is your waist circumference divided by your hip circumference. A higher ratio means more weight carried around the middle.

WHR = waist ÷ hip

Work it out with the Waist-to-Hip Ratio Calculator.

Math terms

What does Discriminant mean?

The discriminant of a quadratic equation is the part of the quadratic formula under the square root. Positive means two real roots, zero means one repeated root, and negative means two complex roots.

b² − 4ac

Work it out with the Quadratic Equation Calculator.

What does Mean, median and mode mean?

The mean is the total divided by how many values there are, the median is the middle value once they are sorted, and the mode is the value that appears most often. They are the three common kinds of average.

Work it out with the Mean Median Mode Calculator.

What does Modulo mean?

Modulo gives the remainder left when one number is divided by another, written a mod n. It is how clock arithmetic works: 14 mod 12 is 2.

Work it out with the Modulo Calculator.

What does Order of operations mean?

The order of operations is the rule for which part of an expression is worked out first: brackets, then powers, then multiplication and division, then addition and subtraction. It is known as PEMDAS in the US and BODMAS in the UK.

Work it out with the Order of Operations Calculator.

What does Percentage change mean?

Percentage change is how much a value has risen or fallen, as a percentage of where it started. It is always measured against the starting value, never the end one.

% change = (new − old) ÷ old × 100

Work it out with the Percentage Change Calculator.

What does Prime factorisation mean?

Prime factorisation writes a whole number as a product of prime numbers. Every whole number above 1 has exactly one such product, apart from the order.

Work it out with the Prime Factorisation Calculator.

What does Proportion mean?

A proportion states that two ratios are equal, A/B = C/D. If three of the four terms are known, cross-multiplying gives the fourth.

A × D = B × C

Work it out with the Proportion Calculator.

What does Pythagorean theorem mean?

The Pythagorean theorem says that in a right-angled triangle the square of the longest side equals the sum of the squares of the other two.

a² + b² = c²

Work it out with the Pythagorean Theorem Calculator.

What does Range mean?

The range of a data set is the highest value minus the lowest. It shows how far apart the extremes are, but says nothing about the values in between.

range = maximum − minimum

Work it out with the Range Calculator.

What does Ratio mean?

A ratio compares two or more quantities by size, written A : B. Simplifying it divides every term by the same number until none can be divided further.

Work it out with the Ratio Calculator.

What does Significant figures mean?

Significant figures are the digits of a number that carry meaning, counted from the first non-zero digit. Rounding to significant figures keeps that many digits however large or small the number is.

Work it out with the Rounding Calculator.

What does Standard deviation mean?

Standard deviation measures how far values typically sit from their mean. A small figure means they cluster close to it; a large one means they are spread out.

Work it out with the Standard Deviation Calculator.

What does Weighted average mean?

A weighted average gives some values more influence than others, using weights such as credit hours or quantities. It is what GPA and average purchase price use.

Σ(value × weight) ÷ Σ weight

Work it out with the Weighted Average Calculator.

Conversion terms

What does KB versus KiB mean?

KB, MB and GB are decimal units, each 1,000 times the last. KiB, MiB and GiB are binary units, each 1,024 times the last. The difference grows with size, which is why a drive shows less space than its label.

Work it out with the Data Storage Converter.

Construction terms

What does Roof pitch mean?

Roof pitch is how steep a roof is, given as rise over run (for example 6:12), as an angle in degrees or as a percentage. A 6:12 pitch rises 6 inches for every 12 inches across.

Work it out with the Roof Pitch Calculator.

Physics terms

What does Ideal gas law mean?

The ideal gas law links the pressure, volume, amount and temperature of a gas. It holds well for most gases at everyday pressures and temperatures.

P × V = n × R × T

Work it out with the Ideal Gas Law Calculator.

What does Kinetic energy mean?

Kinetic energy is the energy an object has because it is moving. It grows with mass and with the square of speed, so doubling speed quadruples it.

KE = ½ × m × v²

Work it out with the Kinetic Energy Calculator.

What does Ohm’s law mean?

Ohm’s law says the current through a conductor is proportional to the voltage across it. Knowing any two of voltage, current and resistance gives the third.

V = I × R

Work it out with the Ohm's Law Calculator.

What does Wavelength mean?

Wavelength is the distance between two matching points on a wave, such as crest to crest. It equals wave speed divided by frequency.

λ = v ÷ f

Work it out with the Wavelength Calculator.

Business terms

What does Break-even point mean?

The break-even point is the level of sales at which revenue exactly covers total costs, so there is neither profit nor loss. Every unit sold beyond it adds profit.

break-even units = fixed costs ÷ (price − variable cost per unit)

Work it out with the Break-Even Point Calculator.

What does Churn mean?

Churn is the share of customers, or of revenue, lost over a period. A lower churn rate means more of what you earn this month is still there next month.

Work it out with the Monthly Recurring Revenue Calculator.

What does Customer lifetime value mean?

Customer lifetime value is the total a customer is expected to bring in over the whole time they stay with you. It tells you how much you can sensibly spend to win a new one.

Work it out with the Customer Lifetime Value Calculator.

What does Employer National Insurance mean?

Employer National Insurance is a payroll cost an employer pays on top of an employee's salary once earnings pass a threshold. It is part of the true cost of employing someone, though it never appears on their payslip.

Work it out with the UK Cost of Employing Someone Calculator.

What does FICA tax mean?

FICA is the US payroll tax that funds Social Security and Medicare. Employees and employers each pay a share, and the Social Security part applies only up to an annual wage limit.

Work it out with the FICA Tax Calculator.

What does FUTA tax mean?

FUTA is the US Federal Unemployment Tax. It is paid by the employer, not deducted from the employee, and applies to the first slice of each employee’s annual wages.

Work it out with the FUTA Tax Calculator.

What does Markup mean?

Markup is profit as a percentage of cost, not of the selling price. A 50% markup on a £100 cost gives a £150 price, which is a margin of about 33%, so markup and margin are never the same figure.

markup = (price − cost) ÷ cost × 100

Work it out with the Markup Calculator.

What does Monthly recurring revenue (MRR) mean?

Monthly recurring revenue is the predictable subscription income a business expects each month. Net new MRR is what is added through new customers and upgrades, less what is lost to downgrades and cancellations.

Work it out with the Monthly Recurring Revenue Calculator.

What does Profit margin mean?

Profit margin is profit as a percentage of revenue: how many pence of every pound sold are kept as profit. Gross, operating and net margins differ in which costs are taken off first.

margin = profit ÷ revenue × 100

Work it out with the Profit Margin Calculator.

What does Return on investment (ROI) mean?

Return on investment is the gain from an investment as a percentage of what it cost. A positive figure means it earned more than it cost; a negative one means a loss.

ROI = (gain − cost) ÷ cost × 100

Work it out with the Return on Investment Calculator.

What does Statutory redundancy pay mean?

Statutory redundancy pay is the legal minimum an employee with at least two years of service is owed when made redundant. It is based on age, length of service and weekly pay, which is capped.

Work it out with the UK Redundancy Pay Calculator.

What does Statutory Sick Pay (SSP) mean?

Statutory Sick Pay is the minimum sick pay an employer must pay an eligible employee who is too ill to work. It is paid at a set weekly rate, and an employer may pay more under a contract.

Work it out with the UK Statutory Sick Pay Calculator.

Engineering terms

What does Chip load mean?

Chip load is the thickness of material each cutting edge removes on every turn of a milling cutter. Too low and the tool rubs; too high and it can break.

chip load = feed rate ÷ (RPM × number of flutes)

Work it out with the CNC Milling Speeds & Feeds Calculator.

What does Total cost of ownership mean?

Total cost of ownership is everything a machine costs over its life, not just the price on the quote: setup, financing, running costs and upkeep.

Work it out with the CNC Lathe Purchase Cost Calculator.