Formulas, worked examples, and applied percentage arithmetic for Australian taxation, finance, and education
Percentage daily values (%DV) on nutrition labels express the proportion of each nutrient relative to a 2,000-calorie reference intake. This guide explains how Australian food labelling standards display energy (kJ), macronutrient ratios, and micronutrient percentages per serving.
Read MoreAlcohol by volume (ABV) measures ethanol concentration as a percentage of total liquid volume. A standard drink in Australia contains 10 grams of ethanol. This guide derives standard drink counts from ABV, container volume, and ethanol density (0.789 g/mL).
Read MoreProbability of precipitation (PoP) expresses the statistical likelihood of rainfall within a defined area during a forecast period. Relative humidity measures water vapour as a percentage of maximum capacity at a given temperature. This guide explains Bureau of Meteorology (BOM) percentage metrics.
Read MoreBattery health percentage measures current maximum capacity relative to original design capacity. Lithium-ion cells degrade through charge cycles; 500 full cycles typically reduce capacity to 80%. This guide covers capacity retention curves, cycle count metrics, and degradation rate calculations.
Read MoreLVR = (Loan Amount ÷ Property Value) × 100. Borrowers exceeding 80% LVR incur Lenders Mortgage Insurance (LMI). This guide details APRA prudential thresholds, deposit-to-LVR relationships, LMI premium calculation, and First Home Guarantee eligibility criteria.
Read MoreConversion rate = (Transactions ÷ Sessions) × 100. Average Australian e-commerce conversion rates range from 1.5% to 2.5%. This guide covers cart abandonment rate (68–75%), bounce rate, click-through rate, and attribution model percentage metrics.
Read MorePercentage-based KPIs quantify employee performance against defined targets. Attainment rate = (Actual ÷ Target) × 100. This guide covers productivity ratios, attendance percentages, quota achievement rates, and performance review scoring under Australian Fair Work standards.
Read MoreInterest rate percentages determine borrowing cost and savings yield. The RBA cash rate influences variable mortgage rates, term deposit returns, and high-interest savings account yields. This guide compares nominal rate, effective annual rate (EAR), and comparison rate calculations.
Read MoreMargin = (Profit ÷ Revenue) × 100. Markup = (Profit ÷ Cost) × 100. A product with $60 cost and $100 revenue has 40% margin and 66.67% markup. This guide derives the conversion formula and provides margin-to-markup reference tables.
Read MoreThe Superannuation Guarantee rate is 12% of ordinary time earnings (2025–26). Concessional contributions cap: $30,000/year. Non-concessional cap: $120,000/year. This guide details SG rate history, salary sacrifice calculations, and compound growth projections to retirement.
Read MoreBody fat percentage = (Fat Mass ÷ Total Body Mass) × 100. Measurement methods: DEXA (±1.5%), BIA (±3–5%), skinfold callipers (±3.5%). Healthy ranges: males 10–20%, females 18–28%. This guide details clinical reference ranges and measurement protocols.
Read MoreAustralian property transactions involve multiple percentage calculations: LVR (loan ÷ value × 100), stamp duty rates (state-variable, 1.4%–5.5%), agent commissions (1.6%–2.5%), and gross rental yield ((Annual Rent ÷ Property Value) × 100). This guide covers each formula with state-specific data.
Read MoreThe Consumer Price Index (CPI) measures percentage change in the price of a weighted basket of goods. Real return = Nominal return − Inflation rate. The RBA targets 2–3% annual inflation. This guide derives purchasing power erosion over time and real return calculations.
Read MoreAustralian universities grade on a percentage-to-classification scale: HD (85–100%), D (75–84%), C (65–74%), P (50–64%), F (0–49%). GPA uses a 7-point scale. This guide covers weighted average computation, credit point allocation, and WAM calculation methodology.
Read MoreAustralia's progressive tax system applies marginal rates: 0% ($0–$18,200), 16% ($18,201–$45,000), 30% ($45,001–$135,000), 37% ($135,001–$190,000), 45% ($190,001+). This guide computes effective tax rate, Medicare levy (2%), and deduction impact on taxable income.
Read MoreTwo-party preferred (2PP) vote percentages derive from primary vote shares redistributed through preference flows. Margin of error at 95% confidence for n=1,000: ±3.1 percentage points. This guide explains preferential voting arithmetic and polling confidence intervals.
Read MorePercentage error = (|Measured Value − True Value| ÷ True Value) × 100. This metric quantifies measurement accuracy in experimental science and engineering. This guide covers absolute error, relative error, systematic versus random error sources, and error propagation rules.
Read MoreCompound interest formula: A = P × (1 + r÷100)ⁿ. $10,000 at 5% for 10 years compounds to $16,288.95 versus $15,000 with simple interest. This guide derives exponential growth curves, compounding frequency impact, and the Rule of 72 doubling-time approximation.
Read MoreBaker's percentage expresses each ingredient as a proportion of flour weight: Hydration% = (Water Weight ÷ Flour Weight) × 100. Yield percentage = (Usable Weight ÷ As-Purchased Weight) × 100. This guide covers recipe scaling ratios, ingredient conversion factors, and portion cost percentages.
Read MoreSports statistics use percentage ratios to normalise performance: batting average = (Runs ÷ Innings), goal accuracy = (Goals ÷ Shots) × 100, win percentage = (Wins ÷ Games) × 100. This guide covers cricket, AFL, NRL, and tennis statistical percentage metrics.
Read MoreThe three core percentage formulas: (1) Part = (P÷100) × Whole, (2) P = (Part÷Whole) × 100, (3) Δ% = ((V₂−V₁)÷V₁) × 100. This guide covers fraction-to-percentage conversion, decimal-to-percentage conversion, mental arithmetic shortcuts, and reverse percentage operations.
Read MorePercentage change = ((New − Original) ÷ Original) × 100. Positive values indicate growth; negative values indicate decline. This guide applies the formula to revenue, cost, headcount, and market share metrics with quarter-over-quarter and year-over-year analysis frameworks.
Read MoreGST is a 10% flat-rate value-added tax under the A New Tax System Act 1999. Add GST: price × 1.1. Remove GST: price ÷ 1.1. GST component: price ÷ 11. This guide covers GST-free items, input tax credits, BAS reporting, and the $75,000 registration threshold.
Read MoreSale price = Original × (1 − Discount%÷100). Stacked discounts compound multiplicatively: 20% then 10% off = ×0.80 × 0.90 = 28% total (not 30%). This guide covers mental arithmetic shortcuts for 10%, 20%, 25%, 33%, and 50% discount calculations.
Read MoreThe 50/30/20 budgeting framework allocates net income by percentage: 50% needs, 30% wants, 20% savings. Savings rate = (Amount Saved ÷ Gross Income) × 100. This guide applies percentage allocation ratios to Australian income levels and cost-of-living benchmarks.
Read MoreCommon percentage errors include: confusing percentage change with percentage points, adding stacked discounts linearly, using the wrong denominator for margin versus markup, and applying percentage increase/decrease asymmetrically. This guide identifies each error type with corrected formulas.
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