📚 KS3 AQA Accounting: Formula & Theorem Quick Reference Handbook | KS3 AQA 会计：公式定理速查手册
Welcome to your essential quick reference guide for Key Stage 3 AQA Accounting. This handbook brings together the most important formulas, equations, and fundamental theorems you will encounter in your studies. Whether you are revising for an end-of-topic test or building a solid foundation for GCSE Accounting, these pages will help you recall key relationships and apply them accurately. Keep this resource handy as you practise recording transactions, preparing financial statements, and analysing business performance.
欢迎使用这份 KS3 AQA 会计必备速查手册。本手册汇集了你在学习过程中将遇到的最重要的公式、等式和基本原理。不论你是在准备单元测验，还是为 GCSE 会计打下扎实基础，这些内容都能帮助你准确回忆并应用关键关系。请将这份资料放在手边，在你练习记录交易、编制财务报表和分析企业业绩时随时查阅。
1. The Accounting Equation | 会计等式
Every accounting system rests on the accounting equation. It shows that a business’s resources (assets) are funded either by borrowing (liabilities) or by the owner’s investment (equity). After every single transaction, the equation must remain in balance; this is the core check that your bookkeeping is accurate.
所有会计系统都建立在会计等式之上。它表明企业的资源（资产）要么通过借贷（负债）获得，要么由所有者投入（所有者权益）。每一笔交易发生后，等式都必须保持平衡；这是检验你簿记是否准确的核心依据。
Assets = Liabilities + Equity
Assets are items of value that the business owns or controls, such as cash, inventory, trade receivables, and property. Liabilities are present obligations arising from past events, for example bank overdrafts, trade payables, and loans. Equity (often called capital for a sole trader) represents the owner’s residual interest in the assets after deducting all liabilities.
资产是企业拥有或控制的有价值项目，例如现金、存货、应收账款和房产。负债是因过去事项而产生的现时义务，比如银行透支、应付账款和贷款。所有者权益（对个体经营者常称为资本）代表扣除所有负债后，所有者对资产的剩余权益。
2. Double-Entry Bookkeeping Rules | 复式记账规则
Double-entry bookkeeping follows a simple rule: every transaction affects at least two accounts. One account is debited, and another is credited, with the total debits always equalling the total credits. The effect on the accounting equation determines which accounts increase or decrease.
复式记账遵循一条简单规则：每笔交易至少影响两个账户。一个账户记借方，另一个账户记贷方，且借方总额始终等于贷方总额。对会计等式的影响决定了哪些账户增加或减少。
Total Debits = Total Credits
The rules for increases and decreases depend on the type of account: for assets, a debit increases the balance and a credit decreases it. For liabilities and equity, a credit increases the balance and a debit decreases it. Income behaves like equity (credit to increase), while expenses behave in the opposite way (debit to increase).
增减规则取决于账户类型：对于资产，借记增加余额，贷记减少余额。对于负债和所有者权益，贷记增加余额，借记减少余额。收入与权益类似（贷记增加），而费用则相反（借记增加）。
| Account type | Debit | Credit |
| Assets | Increase | Decrease |
| Liabilities | Decrease | Increase |
| Equity (Capital) | Decrease | Increase |
| Income (Revenue) | Decrease | Increase |
| Expenses | Increase | Decrease |
These rules ensure the accounting equation always stays balanced. When you record a sale for cash, you debit Cash (asset increase) and credit Sales Income (income increase). For a purchase on credit, you debit Purchases (expense increase) and credit Trade Payables (liability increase).
这些规则保证了会计等式始终平衡。当你记录一笔现金销售时，借记现金（资产增加）并贷记销售收入（收入增加）。对于赊购，则借记采购（费用增加）并贷记应付账款（负债增加）。
3. Income Statement (Profit & Loss) Formulas | 利润表公式
The income statement shows whether a business has made a profit or a loss over a period. It lists revenues and deducts costs in a structured way. The two main measures of profit – gross profit and net profit – are calculated using straightforward formulas.
利润表反映企业在一个期间内是盈利还是亏损。它按结构化方式列示收入并扣除成本。两个主要的利润指标——毛利和净利润——用简单的公式计算。
Gross Profit = Sales Revenue – Cost of Sales
Cost of sales (or cost of goods sold) includes the direct costs of making or buying the products sold, such as raw materials and purchases adjusted for opening and closing inventory. Gross profit measures how efficiently a business turns sales into profit before deducting overheads.
销售成本包括制造或购买已售产品的直接成本，例如原材料和经过期初期末存货调整后的采购额。毛利衡量企业在扣除间接费用之前，将销售转化为利润的效率。
Net Profit = Gross Profit – Other Operating Expenses
Other operating expenses (or overheads) include rent, salaries, advertising, utilities, and depreciation. Net profit is the ‘bottom line’ – the profit remaining after all running costs have been subtracted. It indicates whether the business is truly profitable.
其他经营费用（间接费用）包括租金、工资、广告费、公共事业费和折旧。净利润是“底线”——扣除所有经营成本后剩余的利润。它表明企业是否真正盈利。
Sometimes you will also see the cost of sales broken down as:
有时你也会看到销售成本分解如下：
Cost of Sales = Opening Inventory + Purchases – Closing Inventory
Remember: in a service business, there may be no inventory, so cost of sales is often simply the direct costs of providing the service.
记住：在服务企业中可能没有存货，因此销售成本通常只是提供服务的直接成本。
4. Statement of Financial Position (Balance Sheet) Checks | 资产负债表核验公式
The statement of financial position (often called the balance sheet) is a snapshot of a business’s assets, liabilities, and equity at a specific date. The fundamental check is that the accounting equation holds. Internally, the layout follows a logic that non-current assets plus net current assets equals equity plus non-current liabilities.
财务状况表（常称为资产负债表）是企业在一个特定日期资产、负债和所有者权益状况的快照。根本性检验就是会计等式必须成立。在格式上，它遵循一种逻辑：非流动资产加上净流动资产等于所有者权益加上非流动负债。
Total Assets = Total Equity + Total Liabilities
When preparing a balance sheet, you can verify your work by comparing the total of the ‘assets’ section with the total of the ‘equity and liabilities’ section. If the two sides do not agree, there is a mistake in the ledger accounts or the extraction of figures.
编制资产负债表时，你可以通过对比“资产”栏总额与“权益和负债”栏总额来检验工作。如果两边不相等，就说明分类账或数据摘录有误。
Another useful relationship within the balance sheet itself:
资产负债表内部另一个有用的关系：
Net Current Assets = Current Assets – Current Liabilities
Net current assets (also called working capital) show the liquid cushion available to meet short-term obligations. A healthy business normally has a positive working capital figure.
净流动资产（也称营运资金）反映了可用于偿还短期债务的流动性缓冲。健康的企业通常营运资金为正数。
5. Gross Profit Margin | 毛利率
Gross profit margin expresses the relationship between gross profit and sales revenue as a percentage. It tells you how much of each pound of sales remains after covering the direct cost of goods sold. A higher margin suggests better control over production or purchasing costs relative to the selling price.
毛利率用百分比表示毛利与销售收入之间的关系。它告诉你每一英镑销售收入在覆盖直接销售成本后还剩多少。较高的毛利率表明相对于售价而言，企业能更好地控制生产或采购成本。
Gross Profit Margin = (Gross Profit ÷ Sales Revenue) × 100%
If a business generates £50,000 of sales and its gross profit is £20,000, the gross profit margin is (20,000 ÷ 50,000) × 100% = 40%. This means 40 pence in every pound of sales contributes towards covering expenses and profit.
如果一家企业销售额为 50,000 英镑，毛利为 20,000 英镑，那么毛利率为 (20,000 ÷ 50,000) × 100% = 40%。这意味着每一英镑销售额中有 40 便士可用于支付费用和创造利润。
Comparing gross profit margin over time or against competitors helps assess whether a business is becoming more or less efficient at turning sales into gross profit.
通过横向对比或与竞争对手比较毛利率，可以判断企业在将销售转化为毛利方面效率是提高还是降低。
6. Net Profit Margin | 净利率
Net profit margin goes a step further, showing the percentage of sales revenue that ends up as net profit after all operating expenses have been deducted. It reflects a business’s overall ability to control both direct and indirect costs.
净利率更进一步，显示了在扣除所有经营费用后，销售收入最终变成净利润的百分比。它反映企业控制直接和间接成本的总体能力。
Net Profit Margin = (Net Profit ÷ Sales Revenue) × 100%
Using the earlier example, if net profit is £8,000 on sales of £50,000, the net profit margin is (8,000 ÷ 50,000) × 100% = 16%. This means that for every £1 of sales, the business keeps 16 pence as net profit. A falling net profit margin might signal rising overheads or inefficient operations.
沿用上例，若销售额 50,000 英镑，净利润为 8,000 英镑，则净利率为 (8,000 ÷ 50,000) × 100% = 16%。这意味着每 1 英镑销售额中，企业净赚 16 便士。净利率下降可能预示着间接费用上升或经营效率低下。
7. Current Ratio (Working Capital Ratio) | 流动比率
The current ratio measures a business’s ability to pay its short-term debts as they fall due. It compares current assets (cash, inventory, trade receivables) with current liabilities (overdrafts, trade payables). A ratio that is too low could indicate a risk of not being able to meet immediate obligations.
流动比率衡量企业偿还到期短期债务的能力。它比较流动资产（现金、存货、应收账款）与流动负债（透支、应付账款）。比率过低可能表明存在无法偿付即时债务的风险。
Current Ratio = Current Assets ÷ Current Liabilities
The result is expressed as a number, for example 2 : 1. A common benchmark is between 1.5 : 1 and 2 : 1, meaning the business has £1.50 to £2 of current assets for every £1 of current liabilities. However, an excessively high current ratio might suggest that resources are not being used efficiently, such as too much cash sitting idle.
结果用数字表示，例如 2 : 1。常见的参考范围在 1.5 : 1 到 2 : 1 之间，意味着每 1 英镑流动负债有 1.50 至 2 英镑流动资产与之对应。但流动比率过高也可能表明资源未得到高效利用，例如现金闲置过多。
8. Acid Test Ratio (Quick Ratio) | 速动比率
The acid test ratio is a stricter measure of liquidity because it excludes inventory from current assets. Inventory may take time to sell and its value could drop, so removing it shows a business’s ability to meet short-term debts using only its most liquid assets.
速动比率是对流动性的更严格衡量，因为它将存货从流动资产中剔除。存货出售需要时间，且其价值可能下跌，因此剔除存货后，可反映企业仅依靠最具流动性的资产偿还短期债务的能力。
Acid Test Ratio = (Current Assets – Inventory) ÷ Current Liabilities
Many accountants use a benchmark of 1 : 1 for this ratio, though it varies by industry. If a business has current assets of £30,000 (including £10,000 inventory) and current liabilities of £15,000, its quick ratio is (30,000 – 10,000) ÷ 15,000 = 1.33 : 1, which is comfortable. A ratio below 0.8 : 1 may cause concern, as the business could struggle to pay bills without selling inventory quickly.
许多会计师将 1 : 1 作为该比率的参考值，但会因行业而异。若企业流动资产为 30,000 英镑（含 10,000 英镑存货），流动负债为 15,000 英镑，则速动比率为 (30,000 – 10,000) ÷ 15,000 = 1.33 : 1，处于安全水平。若比率低于 0.8 : 1，则可能令人担忧，因为企业若不快速出售存货，可能难以支付账单。
9. Return on Capital Employed (ROCE) | 运用资本回报率
ROCE measures how efficiently a business generates profit from the money invested in it. ‘Capital employed’ often means total equity plus non-current liabilities, or total assets minus current liabilities. It is a key indicator of overall profitability and performance.
运用资本回报率衡量企业利用投入的资金创造利润的效率。“运用资本”通常指所有者权益总额加上非流动负债，或总资产减去流动负债。它是衡量整体盈利能力和绩效的关键指标。
ROCE = (Net Profit ÷ Capital Employed) × 100%
Assume a business has a net profit of £12,000 and capital employed of £80,000. Its ROCE is (12,000 ÷ 80,000) × 100% = 15%. This can be compared to bank interest rates or rival companies’ ROCE figures. A higher ROCE generally means the business is using its funds wisely.
假设某企业净利润为 12,000 英镑，运用资本为 80,000 英镑，则 ROCE 为 (12,000 ÷ 80,000) × 100% = 15%。可与银行利率或竞争对手的 ROCE 数值进行比较。ROCE 越高，通常意味着企业资金运用越得当。
As a simplified variation, some KS3 courses treat capital employed as the total of owner’s equity and long-term loans. Always check which definition your specific syllabus expects.
作为一个简化变式，一些 KS3 课程将运用资本视为所有者权益与长期贷款的总和。务必确认你所学的教学大纲要求使用哪种定义。
10. Break-even Point Formula | 盈亏平衡点公式
Break-even analysis helps a business work out how many units it must sell to cover all its costs – the point at which total revenue equals total costs, resulting in neither profit nor loss. Understanding the break-even point is vital for planning and setting sales targets.
盈亏平衡分析帮助企业计算出必须销售多少单位产品才能覆盖全部成本——即总收入等于总成本、既无利润也无亏损的那一点。理解盈亏平衡点对于规划和制定销售目标至关重要。
Break-even Point (units) = Total Fixed Costs ÷ (Selling Price per Unit – Variable Cost per Unit)
The bottom part of the formula, (Selling Price per Unit – Variable Cost per Unit), is called ‘contribution per unit’. It shows how much each unit sold contributes towards covering fixed costs and then generating profit.
公式的下半部分（单位售价 – 单位变动成本）称为“单位贡献毛益”。它表明每售出一单位产品对弥补固定成本并进而创造利润的贡献额。
For example, a company has fixed costs of £10,000, selling price £25 per unit, and variable cost £15 per unit. The break-even point is 10,000 ÷ (25 – 15) = 10,000 ÷ 10 = 1,000 units. The business must therefore sell 1,000 units to break even.
例如，一家企业固定成本为 10,000 英镑，单位售价为 25 英镑，单位变动成本为 15 英镑。盈亏平衡点为 10,000 ÷ (25 – 15) = 10,000 ÷ 10 = 1,000 单位。因此，该企业必须销售 1,000 单位才能实现盈亏平衡。
You can also express break-even in sales revenue: Break-even Revenue = Break-even Units × Selling Price per Unit. In the example this is 1,000 × £25 = £25,000.
也可以用销售收入来表示盈亏平衡：盈亏平衡销售收入 = 盈亏平衡单位数 × 单位售价。上例中即 1,000 × 25 = 25,000 英镑。
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