📚 KS3 CAIE Accounting: Formulas and Theorems Quick Reference Handbook | KS3 CAIE 会计：公式定理速查手册
Welcome to your KS3 CAIE Accounting formula and theorem quick reference handbook. This guide brings together all the essential formulas and concepts you need to master the basics of accounting. From the fundamental accounting equation to profitability ratios, liquidity measures, depreciation methods and break-even analysis, each section is presented with clear formulas, explanations and worked examples. Keep this handbook handy as you practise past questions and prepare for your assessments.
欢迎使用 KS3 CAIE 会计公式定理速查手册。本指南汇集了您掌握会计基础所需的所有关键公式和概念。从基本会计等式到盈利能力比率、流动性指标、折旧方法以及盈亏平衡分析，每个部分都配有清晰的公式、解释和计算示例。复习备考时请随身携带本手册，随时查阅。
1. The Accounting Equation | 会计等式
Assets = Liabilities + Equity
资产 = 负债 + 所有者权益
This equation is the foundation of double-entry bookkeeping. It shows that everything a business owns (assets) is financed either by borrowing (liabilities) or by the owner’s investment (equity). After every transaction, the total assets must equal the total of liabilities plus equity.
该等式是复式记账的基础。它表明企业拥有的所有资源（资产）要么通过借款（负债）融资，要么通过所有者投资（所有者权益）融资。每笔交易发生后，总资产必须等于负债加所有者权益之和。
For example, if a business starts with £10,000 cash from the owner, the equation becomes: Assets (Cash) = £10,000, Liabilities = £0, Equity = £10,000. If the business later borrows £3,000 from a bank, assets increase by £3,000 (cash) and liabilities increase by £3,000, so the equation remains balanced at £13,000 = £3,000 + £10,000.
例如，如果企业从所有者那里获得 10000 英镑现金启动资金，等式变为：资产（现金）= 10000 英镑，负债 = 0 英镑，所有者权益 = 10000 英镑。如果企业随后从银行借款 3000 英镑，资产增加 3000 英镑（现金），负债增加 3000 英镑，等式保持平衡：13000 = 3000 + 10000。
2. Double-Entry Principle | 复式记账原理
Total Debits = Total Credits
总借方金额 = 总贷方金额
Every accounting transaction affects at least two accounts – one account is debited and another is credited. The total value of debits must always equal the total value of credits. This dual effect keeps the accounting equation in balance.
每笔会计交易至少影响两个账户——一个账户记入借方，另一个账户记入贷方。借方总额必须始终等于贷方总额。这种双重影响保持了会计等式的平衡。
For instance, when a business sells goods for £500 in cash, the cash account is debited (increase in asset) and the sales revenue account is credited (increase in income). The debit of £500 equals the credit of £500.
例如，当企业以现金出售商品获得 500 英镑时，现金账户记入借方（资产增加），销售收入账户记入贷方（收入增加）。借方 500 英镑等于贷方 500 英镑。
3. Profit Calculation | 利润计算
Gross Profit = Sales Revenue − Cost of Goods Sold
毛利 = 销售收入 − 销货成本
Net Profit = Gross Profit − Expenses
净利润 = 毛利 − 费用
Gross profit shows how efficiently a business turns sales into profit before deducting overheads. Net profit is the final profit after subtracting all operating expenses such as rent, salaries and utilities.
毛利显示了企业在扣除运营开销之前将销售收入转化为利润的效率。净利润是减去租金、工资和水电费等所有运营费用后的最终利润。
Example: A shop sells goods for £8,000 and the cost of those goods was £5,000. Gross profit = £8,000 − £5,000 = £3,000. If total expenses amount to £1,200, then net profit = £3,000 − £1,200 = £1,800.
示例：一家商店销售收入 8000 英镑，商品成本为 5000 英镑。毛利 = 8000 − 5000 = 3000 英镑。如果总费用为 1200 英镑，则净利润 = 3000 − 1200 = 1800 英镑。
4. Gross Profit Margin | 毛利率
Gross Profit Margin = (Gross Profit ÷ Revenue) × 100%
毛利率 = (毛利 ÷ 收入) × 100%
This ratio expresses gross profit as a percentage of sales revenue. A higher gross profit margin indicates that a business is keeping more money from each sale to cover other expenses and generate profit.
该比率将毛利表示为销售收入的一个百分比。毛利率越高，表明企业从每笔销售中留存的用于覆盖其他费用和产生利润的资金就越多。
Using the previous example with £3,000 gross profit and £8,000 revenue, the gross profit margin = (3,000 ÷ 8,000) × 100% = 37.5%. For every £1 of sales, the business retains 37.5p after paying for the goods sold.
使用前面的例子，毛利 3000 英镑、收入 8000 英镑，毛利率 = (3000 ÷ 8000) × 100% = 37.5%。每 1 英镑的销售收入，企业在支付商品成本后可保留 37.5 便士。
5. Net Profit Margin | 净利率
Net Profit Margin = (Net Profit ÷ Revenue) × 100%
净利率 = (净利润 ÷ 收入) × 100%
Net profit margin measures how much of each pound of sales is left as profit after all expenses. It is a key indicator of a business’s overall profitability and cost control.
净利率衡量每英镑销售收入在扣除所有费用后还剩下多少利润。它是企业整体盈利能力和成本控制的关键指标。
If net profit is £1,800 and revenue is £8,000, the net profit margin = (1,800 ÷ 8,000) × 100% = 22.5%. This means the business earns a net profit of 22.5p for every £1 of revenue.
如果净利润为 1800 英镑，收入为 8000 英镑，净利率 = (1800 ÷ 8000) × 100% = 22.5%。这意味着企业每 1 英镑的收入可赚取 22.5 便士的净利润。
6. Current Ratio | 流动比率
Current Ratio = Current Assets ÷ Current Liabilities
流动比率 = 流动资产 ÷ 流动负债
The current ratio assesses a company’s ability to pay its short-term obligations. A ratio above 1 indicates that current assets exceed current liabilities, providing a safety cushion. Many businesses aim for a current ratio between 1.5 and 2.
流动比率用于评估企业偿还短期债务的能力。比率高于 1 表明流动资产超过流动负债，提供了安全缓冲。许多企业将流动比率目标设定在 1.5 至 2 之间。
Example: Current assets = £25,000 (cash, inventory, receivables), current liabilities = £15,000 (payables, short-term loans). Current ratio = 25,000 ÷ 15,000 = 1.67. The business has £1.67 of current assets for every £1 of current liabilities.
示例：流动资产 = 25000 英镑（现金、存货、应收账款），流动负债 = 15000 英镑（应付账款、短期借款）。流动比率 = 25000 ÷ 15000 = 1.67。企业每 1 英镑的流动负债对应 1.67 英镑的流动资产。
7. Quick Ratio (Acid Test) | 速动比率（酸性测试）
Quick Ratio = (Current Assets − Inventory) ÷ Current Liabilities
速动比率 = (流动资产 − 存货) ÷ 流动负债
The quick ratio is a stricter measure of liquidity because it excludes inventory, which may not be quickly converted into cash. A quick ratio of at least 1 is generally considered satisfactory.
速动比率是一项更严格的流动性衡量指标，因为它剔除了可能无法快速变现的存货。速动比率不低于 1 通常被视为令人满意。
Using the same figures, if inventory makes up £8,000 of current assets, quick assets = £25,000 − £8,000 = £17,000. Quick ratio = 17,000 ÷ 15,000 = 1.13. The business can cover its current liabilities without relying on inventory sales.
沿用相同数据，如果存货为 8000 英镑，则速动资产 = 25000 − 8000 = 17000 英镑。速动比率 = 17000 ÷ 15000 = 1.13。企业无需依赖存货销售即可偿还流动负债。
8. Depreciation – Straight-Line Method | 折旧—直线法
Annual Depreciation = (Cost − Residual Value) ÷ Useful Life
年折旧额 = (成本 − 残值) ÷ 使用年限
Depreciation spreads the cost of a non-current asset over its useful life. The straight-line method charges an equal amount of depreciation each year, making it simple and predictable.
折旧将非流动资产成本在其使用寿命内分摊。直线法每年计提等额的折旧费用，计算简单且易于预测。
Example: A machine costs £12,000, has an estimated residual value of £2,000 and a useful life of 5 years. Annual depreciation = (12,000 − 2,000) ÷ 5 = £2,000. Each year, the income statement will show a depreciation expense of £2,000.
示例：一台机器成本为 12000 英镑，估计残值 2000 英镑，使用年限 5 年。年折旧额 = (12000 − 2000) ÷ 5 = 2000 英镑。每年利润表将显示 2000 英镑的折旧费用。
9. Depreciation – Reducing Balance Method | 折旧—余额递减法
Annual Depreciation = Net Book Value × Depreciation Rate
年折旧额 = 账面净值 × 折旧率
The reducing balance method applies a fixed percentage to the asset’s net book value (cost minus accumulated depreciation) each year. This results in higher depreciation charges in the early years and lower charges later.
余额递减法每年将固定百分比应用于资产的账面净值（成本减累计折旧）。这样会导致早期折旧费用较高，后期较低。
Assume a machine costing £10,000 is depreciated at 20% per annum. Year 1 depreciation = 10,000 × 20% = £2,000, net book value = £8,000. Year 2 depreciation = 8,000 × 20% = £1,600, net book value = £6,400, and so on.
假设一台机器成本 10000 英镑，每年按 20% 计提折旧。第一年折旧 = 10000 × 20% = 2000 英镑，账面净值 = 8000 英镑。第二年折旧 = 8000 × 20% = 1600 英镑，账面净值 = 6400 英镑，依此类推。
10. Cost of Goods Sold (COGS) | 销货成本
COGS = Opening Inventory + Purchases − Closing Inventory
销货成本 = 期初存货 + 本期购货 − 期末存货
COGS represents the direct cost of goods that a business has sold during a period. It is deducted from sales revenue to arrive at gross profit. Accurate inventory counting is essential for calculating COGS.
销货成本表示企业在一个时期内已售商品的直接成本。它从销售收入中扣除以得出毛利。准确的存货清点对于计算销货成本至关重要。
Example: Opening inventory = £4,000, purchases during the year = £15,000, closing inventory = £3,500. COGS = 4,000 + 15,000 − 3,500 = £15,500. This is the cost that will be matched against sales revenue.
示例：期初存货 4000 英镑，年度购货 15000 英镑，期末存货 3500 英镑。销货成本 = 4000 + 15000 − 3500 = 15500 英镑。该成本将与销售收入配比。
11. Break-Even Point | 盈亏平衡点
Break-Even Point (units) = Fixed Costs ÷ (Selling Price per Unit − Variable Cost per Unit)
盈亏平衡点（数量） = 固定成本 ÷ (单位售价 − 单位变动成本)
The break-even point is the level of sales where total revenue equals total costs, resulting in neither profit nor loss. It helps businesses plan output levels and pricing.
盈亏平衡点是指总收入等于总成本的销售水平，此时既无利润也无亏损。它有助于企业规划产量水平和定价。
Suppose a product sells for £25 per unit, variable cost is £10 per unit, and total fixed costs are £30,000. Contribution per unit = £25 − £10 = £15. Break-even units = 30,000 ÷ 15 = 2,000 units. Selling 2,000 units covers all costs exactly.
假设某产品单位售价 25 英镑，单位变动成本 10 英镑，总固定成本为 30000 英镑。单位贡献毛利 = 25 − 10 = 15 英镑。盈亏平衡数量 = 30000 ÷ 15 = 2000 件。销售 2000 件恰好覆盖所有成本。
12. Mark-up and Margin | 加价率与毛利率
Markup = (
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