The accounting equation is Assets = Liabilities + Equity. It says that everything a business owns was paid for in one of two ways: with money it owes to others (liabilities), or with money that belongs to its owners (equity). Every transaction keeps the two sides equal, which is why a correct balance sheet always balances.
The equation looks almost too simple to matter, but all of double-entry bookkeeping is built around it. This guide explains each term, shows the equation moving through a run of transactions, and ends with practice questions of the kind that appear in quizzes and exams.
The three parts
- Assets are resources the business controls that will bring future benefit: cash, receivables, inventory, equipment, buildings.
- Liabilities are what the business owes to outsiders: suppliers, lenders, employees owed wages, the tax authorities.
- Equity is what is left for the owners once every liability is paid. It is a claim on the assets, not a separate pile of money.
Rearranged, the equation becomes Equity = Assets − Liabilities. That is the cleanest definition of equity there is. If a business has $80,000 of assets and owes $30,000, its owners' stake is $50,000.
The expanded accounting equation
Equity changes for four reasons: owners put money in, owners take money out, the business earns revenue, and it incurs expenses. Writing those out gives the expanded equation:
Assets = Liabilities + Owner's capital + Revenue − Expenses − Drawings
For a company, capital becomes share capital and drawings become dividends. This version explains why revenue and expenses affect the balance sheet at all: revenue increases equity, expenses reduce it, and the net result is profit, which ends up in retained earnings.
Why the equation always balances
Double-entry bookkeeping records every transaction with equal debits and credits, and the debit and credit rules are designed so that each entry keeps the equation true. It is not luck that the balance sheet balances. Every single transaction is recorded in a way that cannot break the equation, provided the entry itself is right. The rules behind that are covered in debits and credits explained.
Watching the equation move
A new business, Clearwater Design, records six transactions in its first month. Watch the totals after each one.
| Transaction | Assets | Liabilities | Equity |
|---|---|---|---|
| 1. Owner invests $10,000 cash | +10,000 cash | +10,000 capital | |
| 2. Borrows $5,000 from the bank | +5,000 cash | +5,000 loan | |
| 3. Buys equipment for $8,000 cash | +8,000 equipment, −8,000 cash | ||
| 4. Earns $2,000 revenue in cash | +2,000 cash | +2,000 revenue | |
| 5. Receives a $600 utility bill, unpaid | +600 payable | −600 expense | |
| 6. Owner withdraws $500 | −500 cash | −500 drawings | |
| Totals | 16,500 | 5,600 | 10,900 |
Check: 5,600 + 10,900 = 16,500. The equation balances after every row, not only at the end. Notice the patterns too:
- Asset swapped for asset (transaction 3): one asset up, another down, totals unchanged.
- Both sides up (1, 2 and 4): assets rise, matched by a liability or equity.
- Both sides down (6): cash leaves, and equity falls with it.
- Right side only (5): a liability rises and equity falls by the same amount, so assets do not change at all.
Practice questions
Try each one before reading the answer.
1. A plant nursery borrows $150,000 from a bank and uses the loan to buy a warehouse. What is the effect on the accounting equation?
Two steps. Borrowing increases assets (cash) by $150,000 and liabilities (bank loan) by $150,000. Buying the warehouse swaps $150,000 of cash for a $150,000 building, so assets stay the same. Overall: assets +$150,000, liabilities +$150,000, equity unchanged.
2. Before a transaction, a laundry business has assets of $4,545, liabilities of $2,300 and owner's equity of $2,245. It buys $1,250 of equipment with cash. What are its total assets now?
$4,545. Cash falls by $1,250 and equipment rises by $1,250, so total assets do not change. This is the most common trick question on the topic: an asset-for-asset swap leaves the totals exactly where they were.
3. A company has assets of $90,000 and equity of $55,000. What are its liabilities?
Liabilities = Assets − Equity = 90,000 − 55,000 = $35,000.
4. During a year, a company's assets rise by $40,000 and its liabilities rise by $15,000. No shares were issued and no dividends were paid. What was its profit?
Equity must have risen by 40,000 − 15,000 = $25,000. With no owner transactions, the whole increase came from profit, so profit was $25,000.
Common mistakes
- Thinking every transaction changes the totals. Asset swaps, such as buying equipment for cash or collecting a receivable, do not.
- Treating drawings or dividends as expenses. They reduce equity directly, but they are not costs of earning revenue.
- Forgetting that expenses can increase liabilities. An unpaid bill reduces equity and increases payables, with no change to assets.
- Calling equity "the cash the owners have". Equity is a claim on all the assets, whatever form they take.
Why it matters beyond the exam
The accounting equation is the reason a trial balance and a balance sheet are expected to balance in the first place. When they do not, the equation is not wrong: an entry somewhere upstream was recorded with unequal sides, posted to the wrong account, or copied incorrectly. Trial balance not balancing walks through how to find it, and the balance sheet guide shows the equation as a finished statement.
Practice it
The quickest way to make the equation instinctive is to record transactions yourself and watch it hold. Accountely's journal entry challenges and balance sheet challenges check every line you enter, and the 30 Days of Accounting series starts from the equation on day one. It's free to start.
Frequently Asked Questions
What is the basic accounting equation?
Assets = Liabilities + Equity. Everything a business owns is financed either by borrowing (liabilities) or by its owners (equity), so the two sides are always equal.
What is the expanded accounting equation?
Assets = Liabilities + Owner's capital + Revenue − Expenses − Drawings. It breaks equity into the four things that change it, which shows how profit and owner withdrawals affect the balance sheet.
Why must the accounting equation always balance?
Because every transaction is recorded with equal debits and credits, and each entry affects the equation by equal amounts on both sides, or by equal and opposite amounts on one side. If the equation does not balance, a recording error has been made.
What is assets minus liabilities?
Assets minus liabilities equals equity, also called net assets. It is the owners' residual interest in the business: what would be left for them if every asset were sold at its book value and every debt paid.