11 Essential Accounting Formulas for Small Businesses

The most useful accounting formulas help a business measure profitability, pricing, liquidity, debt, inventory, and return on investment. These include the accounting equation, break-even point, cash ratio, cost of goods sold, debt-to-equity ratio, gross profit, inventory shrinkage, markup, net income, return on investment, and straight-line depreciation.

For residential contractors and specialty-trade bookkeepers, these formulas can answer practical questions: Are projects priced high enough? Can the business cover upcoming obligations? How much gross profit does each type of work generate? Is equipment producing an acceptable return?

The formulas are straightforward, but their results are only as reliable as the bookkeeping information used in them.

Quick answers about accounting formulas

What is the most important accounting formula?

The fundamental accounting equation is:

Assets = Liabilities + Owner’s Equity

It is the foundation of the balance sheet and double-entry accounting.

Which formula tells you whether a business is profitable?

The net income formula measures overall profitability:

Net Income = Total Revenue − Total Expenses

A positive result means the business generated a profit for the period. A negative result means it generated a loss.

Which formula helps set prices?

Markup percentage and break-even formulas can both support pricing decisions. Markup measures how much is added to cost, while break-even analysis estimates how much must be sold to cover fixed and variable costs.

Are markup and profit margin the same?

No. Markup compares profit with cost. Gross profit margin compares gross profit with revenue. The same sale will produce different markup and margin percentages.

How often should accounting formulas be reviewed?

Contractor bookkeeping teams may review project margins and cash positions weekly, profitability monthly, and debt or equipment investment metrics quarterly. The appropriate schedule depends on transaction volume and how quickly costs change.

Do these formulas replace an accountant?

No. Accounting formulas help explain financial information, but they do not determine the correct accounting method, tax treatment, depreciation method, or financial decision in every situation.

Accounting formulas at a glance

Accounting formula	Calculation	What it measures
Accounting equation	Assets = Liabilities + Equity	Whether the balance sheet balances
Break-even point	Fixed Costs ÷ Contribution Per Unit	Units needed to cover costs
Cash ratio	Cash and Cash Equivalents ÷ Current Liabilities	Immediate liquidity
Cost of goods sold	Beginning Inventory + Purchases − Ending Inventory	Inventory costs associated with sales
Debt-to-equity ratio	Total Liabilities ÷ Total Equity	Reliance on debt financing
Gross profit	Revenue − Cost of Goods Sold	Profit before operating expenses
Gross profit margin	Gross Profit ÷ Revenue × 100	Gross profit as a percentage of revenue
Inventory shrinkage	Recorded Inventory − Physical Inventory	Missing or unaccounted-for inventory
Markup percentage	(Selling Price − Cost) ÷ Cost × 100	Amount added to cost when setting a price
Net income	Total Revenue − Total Expenses	Overall profit or loss
Return on investment	Net Gain ÷ Investment Cost × 100	Return generated by an investment
Straight-line depreciation	(Asset Cost − Salvage Value) ÷ Useful Life	Equal annual depreciation expense

1. What is the accounting equation?

The accounting equation shows the relationship among a business’s assets, liabilities, and equity.

Assets = Liabilities + Owner’s Equity

• Assets are resources the business controls, such as cash, accounts receivable, vehicles, tools, inventory, and equipment.
• Liabilities are financial obligations, including unpaid bills, credit card balances, loans, and taxes owed.
• Owner’s equity represents the owner’s financial interest after liabilities are subtracted from assets.

The SEC describes the same fundamental balance-sheet relationship as assets equaling liabilities plus equity.

Accounting equation example

A residential contractor has:

• $125,000 in assets
• $70,000 in liabilities
• $55,000 in owner’s equity

The equation is:

$125,000 = $70,000 + $55,000

Both sides equal $125,000, so the balance sheet balances.

If the two sides do not agree, the bookkeeping records may contain a missing entry, duplicate entry, incorrect balance, or classification problem. A balanced equation does not guarantee that every transaction is correct, but an unbalanced equation signals that something requires investigation.

Use our free balance sheet template to organize the amounts used in this formula.

2. How do you calculate the break-even point?

The break-even point is the amount a business must sell before total revenue equals total costs. At the break-even point, the business has generated neither a profit nor a loss.

For units or individual services, use:

Break-Even Units = Fixed Costs ÷ (Selling Price Per Unit − Variable Cost Per Unit)

The amount inside the parentheses is the contribution generated by each unit.

• Fixed costs generally remain relatively stable regardless of sales volume, such as rent, software subscriptions, and certain administrative salaries.
• Variable costs change as work increases, such as materials, transaction fees, and certain types of direct labor.
• Selling price is the amount charged for each unit or service.

The SBA uses this formula for calculating break-even units and notes that break-even analysis examines the relationship among fixed costs, variable costs, and profit.

Break-even example for a service contractor

An HVAC contractor offers a seasonal maintenance service with:

• Monthly fixed costs allocated to the service: $9,000
• Price per appointment: $225
• Variable labor and materials per appointment: $75

First, calculate contribution per appointment:

$225 − $75 = $150

Then calculate the break-even point:

$9,000 ÷ $150 = 60 appointments

The contractor must complete 60 appointments during the month to cover the allocated fixed and variable costs.

Break-even analysis is an estimate. The result can change when labor rates, material prices, service mix, discounts, or overhead allocations change.

3. What is the cash ratio?

The cash ratio measures whether available cash and cash equivalents could cover current liabilities.

Cash Ratio = Cash and Cash Equivalents ÷ Current Liabilities

Cash equivalents are highly liquid short-term holdings that can generally be converted to cash quickly. Current liabilities are obligations generally due within one year.

Cash ratio example

A plumbing contractor has:

• $80,000 in cash and cash equivalents
• $100,000 in current liabilities

The cash ratio is:

$80,000 ÷ $100,000 = 0.80

That means the business has 80 cents in cash and cash equivalents for every dollar of current liabilities.

A ratio below 1 does not automatically mean the business is unhealthy. The company may expect customer payments or other cash inflows before its obligations are due. Likewise, an unusually high cash ratio is not automatically ideal because excess cash may be available for equipment, hiring, debt reduction, or other productive uses.

Compare the result with the company’s payment cycle, cash-flow forecast, industry, and historical performance.

4. How do you calculate cost of goods sold?

For a business that carries inventory, the standard cost of goods sold formula is:

COGS = Beginning Inventory + Inventory Purchases − Ending Inventory

• Beginning inventory is the value of inventory available at the start of the period.
• Purchases are additional inventory costs incurred during the period.
• Ending inventory is the value remaining at the end of the period.

Cost of goods sold example

An electrical contractor maintains an inventory of commonly used components.

For the month, it has:

• Beginning inventory: $18,000
• Additional inventory purchases: $9,500
• Ending inventory: $16,250

The calculation is:

$18,000 + $9,500 − $16,250 = $11,250

The contractor’s inventory-based cost of goods sold is $11,250.

How does COGS work for contractors?

A contractor may record direct job costs as cost of goods sold or cost of revenue even when those costs are not pulled from inventory.

Depending on the company’s accounting method, direct costs may include:

• Job materials
• Field labor
• Subcontractor charges
• Equipment rentals
• Permits
• Freight
• Other costs directly connected with completing customer work

The inventory formula does not calculate every type of contractor COGS. Work-in-progress accounting, job costing, and revenue-recognition rules can make the calculation more complex.

5. What is the debt-to-equity ratio?

The debt-to-equity ratio compares total liabilities with total equity.

Debt-to-Equity Ratio = Total Liabilities ÷ Total Equity

The ratio helps show how much of the business is financed through obligations compared with the owners’ financial interest.

Debt-to-equity example

A roofing company has:

• Total liabilities: $240,000
• Total equity: $160,000

The calculation is:

$240,000 ÷ $160,000 = 1.5

The company has $1.50 in liabilities for every $1 of equity.

A higher ratio generally indicates greater reliance on debt, but there is no single ideal ratio for every business. Equipment-intensive contractors may naturally carry more debt than businesses that require fewer physical assets.

Evaluate the ratio using:

• Historical company results
• Industry norms
• Interest rates
• Debt payment requirements
• Cash-flow stability
• Planned equipment or expansion investments

A negative debt-to-equity ratio may occur when total equity is negative. In that situation, the result requires additional analysis and should not be interpreted like a conventional positive ratio.

6. How do you calculate gross profit and gross profit margin?

Gross profit is the amount remaining after subtracting the direct cost of delivering products or services from revenue.

Gross Profit = Revenue − Cost of Goods Sold

Gross profit margin converts gross profit into a percentage of revenue:

Gross Profit Margin = Gross Profit ÷ Revenue × 100

Gross profit is reported as a dollar amount. Gross profit margin is reported as a percentage.

Contractor gross profit example

A remodeling contractor completes $120,000 of work during the month. Direct materials, field labor, and subcontractor costs total $78,000.

Gross profit is:

$120,000 − $78,000 = $42,000

Gross profit margin is:

$42,000 ÷ $120,000 × 100 = 35%

The business retained 35 cents of gross profit from every dollar of revenue before paying overhead, interest, taxes, and other expenses.

A 35% margin is not automatically good or bad. The contractor should compare it with:

• The estimated margin for those projects
• Previous accounting periods
• Similar types of work
• The overhead required to operate
• The margin needed to produce an acceptable net profit

7. How do you calculate inventory shrinkage?

Inventory shrinkage is the difference between inventory shown in the accounting records and inventory physically available.

Inventory Shrinkage = Recorded Inventory Value − Physical Inventory Value

To express the difference as a percentage:

Inventory Shrinkage Percentage = Inventory Shrinkage ÷ Recorded Inventory Value × 100

Inventory shrinkage example

An electrical contractor’s records show $30,000 of parts and supplies. A physical count finds only $28,500.

Inventory shrinkage is:

$30,000 − $28,500 = $1,500

Inventory shrinkage percentage is:

$1,500 ÷ $30,000 × 100 = 5%

Shrinkage does not automatically prove theft. Possible causes include:

• Damaged materials
• Counting mistakes
• Data-entry errors
• Unrecorded project usage
• Incorrect units of measure
• Supplier shortages
• Materials stored in a vehicle or at a job site
• Theft or unauthorized use

Investigate the cause before adjusting the records or changing purchasing controls.

8. How do you calculate markup percentage?

Markup percentage measures how much a business adds to cost when setting a selling price.

Markup Percentage = (Selling Price − Cost) ÷ Cost × 100

Markup example

A contractor pays $50 for a component and charges the customer $75.

The markup is:

($75 − $50) ÷ $50 × 100 = 50%

The contractor applied a 50% markup to the cost.

What is the difference between markup and margin?

Markup and gross margin use different starting points:

• Markup divides the profit by cost.
• Gross margin divides the gross profit by selling price.

Using the same $50 cost and $75 selling price:

Markup: ($75 − $50) ÷ $50 × 100 = 50%

Gross margin: ($75 − $50) ÷ $75 × 100 = 33.3%

A 50% markup produces a 33.3% gross margin in this example.

There is no universally safe markup. Pricing should consider labor, overhead, market conditions, warranty work, discounts, payment delays, risk, and the desired net profit.

9. How do you calculate net income?

Net income is the amount remaining after all expenses for the period are subtracted from revenue.

The simplest formula is:

Net Income = Total Revenue − Total Expenses

A more detailed version is:

Net Income = Revenue − COGS − Operating Expenses − Interest − Taxes

The exact presentation depends on the business’s financial statements and accounting method.

Net income example

A residential contractor reports:

• Revenue: $180,000
• Cost of goods sold: $108,000
• Operating expenses: $48,000
• Interest and taxes: $7,000

The calculation is:

$180,000 − $108,000 − $48,000 − $7,000 = $17,000

Net income for the period is $17,000.

Is net income the same as cash flow?

No. Net income measures accounting profit. Cash flow measures money moving into and out of the business.

A contractor may report a profit but still experience cash-flow pressure if customers have not paid their invoices, cash was used to purchase equipment, or loan principal payments reduced the available bank balance.

Our guides to cash-flow analysis and the net cash-flow formula explain that distinction in more detail.

You can also use our free income statement template to organize revenue and expenses.

10. How do you calculate return on investment?

Return on investment, or ROI, compares an investment’s net gain with its cost.

ROI = Net Gain From Investment ÷ Investment Cost × 100

Net gain can also be expressed as:

Net Gain = Financial Benefit − Investment Cost

Equipment ROI example

A plumbing contractor spends $20,000 on inspection equipment. Over the evaluation period, the equipment produces $27,000 in additional financial benefit after related operating costs.

Net gain is:

$27,000 − $20,000 = $7,000

ROI is:

$7,000 ÷ $20,000 × 100 = 35%

The estimated ROI is 35%.

ROI is useful for comparing investments, but it has limitations. A basic ROI calculation does not automatically consider:

• How long the return took to generate
• Financing costs
• Taxes
• Inflation
• Risk
• Different useful lives
• The time value of money
• Benefits that are difficult to measure

Compare investments over consistent periods and use the same definition of financial benefit for each option.

11. How do you calculate straight-line depreciation?

Straight-line depreciation spreads an asset’s depreciable cost evenly across its estimated useful life.

Annual Straight-Line Depreciation = (Asset Cost − Salvage Value) ÷ Useful Life

• Asset cost generally includes the costs necessary to acquire and prepare the asset for use.
• Salvage value is the estimated value remaining at the end of its useful life.
• Useful life is the period over which the asset is expected to provide value.

Straight-line depreciation example

An electrical contractor purchases testing equipment for $12,000. The equipment has:

• An estimated useful life of five years
• An estimated salvage value of $2,000

The annual depreciation calculation is:

($12,000 − $2,000) ÷ 5 = $2,000

The business would record $2,000 of straight-line depreciation per year for financial-reporting purposes, assuming those estimates and that method are appropriate.

Is straight-line depreciation always used for taxes?

No. Tax depreciation does not always follow the simple straight-line calculation.

The IRS explains that depreciation may involve the Modified Accelerated Cost Recovery System, Section 179, special depreciation allowances, property classifications, conventions, and business-use limitations. Only the portion used for business or investment purposes may generally be depreciable.

Consult an accountant or tax professional before deciding how to depreciate vehicles, tools, machinery, buildings, or other business assets.

Which financial statements provide the numbers for these formulas?

The inputs generally come from three primary financial statements.

Financial statement	Examples of formula inputs
Balance sheet	Assets, liabilities, equity, cash, inventory, and current obligations
Profit and loss statement	Revenue, COGS, operating expenses, gross profit, and net income
Cash-flow statement	Cash received, cash paid, and changes in cash during a period

Other information may come from:

• Inventory counts
• Project or job-cost reports
• Equipment records
• Loan statements
• Customer invoices
• Vendor bills
• Payroll reports
• Receipts
• Bank and credit card transactions

Use the same reporting period and accounting basis when comparing results. Mixing monthly revenue with annual expenses, or cash-basis figures with accrual-basis figures, can produce a misleading calculation.

How should contractors use accounting formulas?

Residential contractors and specialty-trade bookkeepers should connect each formula with a specific decision.

Business question	Useful formula
Are projects generating enough profit before overhead?	Gross profit margin
How much work must we sell to cover fixed costs?	Break-even point
Can we cover near-term obligations with available cash?	Cash ratio
Are we relying heavily on borrowed funds?	Debt-to-equity ratio
Are materials disappearing or going unrecorded?	Inventory shrinkage
Are we adding enough to direct costs when setting prices?	Markup percentage
Is the entire business profitable after overhead?	Net income
Did new equipment produce an acceptable financial return?	ROI
How should an asset’s cost be allocated over time?	Depreciation
Do assets equal liabilities plus equity?	Accounting equation

Formulas are most useful when compared across time. A single gross margin percentage provides limited context. Monthly or quarterly trends can show whether labor productivity, project mix, material costs, or pricing is improving or weakening.

Common mistakes when using accounting formulas

Using incomplete bookkeeping data

Missing expenses can make margins and net income appear stronger than they are. Missing revenue can produce the opposite effect.

Mixing accounting periods

Use numbers from the same month, quarter, or year unless the formula specifically requires otherwise.

Comparing cash with profit

Cash, revenue, and net income are related but different. A profitable company can still have cash-flow problems.

Confusing markup with margin

A 50% markup does not produce a 50% gross margin. Calculate the metric you actually use for pricing and performance.

Treating every ratio benchmark as universal

Appropriate margins, liquidity ratios, and debt levels vary by industry, company maturity, business model, and risk.

Ignoring accounting methods

Cash-basis and accrual-basis reports can recognize revenue and expenses at different times. That difference affects formula inputs and comparisons.

Using estimates without updating them

Material costs, labor rates, overhead, equipment usage, and salvage values can change. Review the inputs instead of reusing outdated assumptions.

How we help organize the information behind the formulas

Accounting formulas depend on complete and accurately categorized financial information.

With Neat, contractor bookkeeping teams can organize receipts and invoices, review extracted transaction details, connect financial accounts, categorize activity, reconcile transactions, and create financial reports.

Our available reporting tools include Profit and Loss, Balance Sheet, Cash Flow, and detailed transaction reports. These reports help organize the revenue, expense, cash, asset, liability, and transaction information used in many of the formulas above.

The software can help organize the inputs, but the person reviewing the books still needs to confirm:

• Transactions are complete
• Expenses are categorized correctly
• Personal activity is excluded
• Supporting documents are attached
• Accounts are reconciled
• Projects and customers are assigned consistently
• Accounting periods and methods are comparable

For a broader process, read our guide to small-business bookkeeping or review these essential bookkeeping terms.

Turn financial data into useful decisions

Accounting formulas turn bookkeeping data into answers. They can show whether pricing covers costs, projects generate sufficient margins, debt is increasing, inventory is missing, or an investment is producing a return.

The most useful approach is to:

1. Maintain complete financial records.
2. Use consistent categories and reporting periods.
3. Calculate the appropriate metric.
4. Compare the result with prior periods and realistic targets.
5. Investigate the reason for meaningful changes.
6. Consult a qualified professional when tax treatment or accounting policy is involved.

When the underlying records are organized and current, these formulas become more than classroom equations. They become practical tools for making better financial decisions.

Start using Neat to organize your financial records and reports.

This article provides general educational information and is not accounting, tax, investment, or legal advice.