How to Calculate Profit for a Small Business (Step by Step)
WadMaster Editor
Mon, Aug 17, 2026
8 min read
To calculate profit for a small business, add the sales for one period, subtract the direct cost of what you sold, then subtract the expenses required to run the business. The number left is your estimated operating profit for that period.
The arithmetic is short. The hard part is putting each number in the right place. Sales are not the same as money entering your bank account, stock purchases are not automatically the cost of what you sold, and profit is not the same as cash you can spend.
What profit are you trying to calculate?
Use one definition consistently. Gross profit shows what your sales left after the direct cost of the goods or work sold. Estimated operating profit goes one step further by subtracting everyday running costs such as rent, salaries, power, data, marketing and bank charges.
This guide stops at estimated operating profit before tax. A formal net-profit figure may also include finance costs, depreciation, tax and other accounting adjustments. Use an accountant for statutory accounts or a tax return; use the method here for a clear monthly management check.
Step 1: Choose one period and one basis
Pick a period before you start: one month is practical for most small businesses. Use the same start and end dates for sales, stock and expenses. Comparing January sales with expenses paid across January and February will give you a tidy answer that means very little.
Also decide whether this is an earned-sales view or a cash view. An earned-sales view counts work delivered or goods sold in the period, even if a customer still owes you. A cash view counts only money collected and costs paid. Both can help, but do not mix them. The worked example below uses earned sales and shows unpaid invoices separately.
Dead stock is stock you have already paid for that is no longer selling. Here is how to find it using the last date each item sold, work out how much cash it is holding, and decide whether to bundle, discount or clear it.
Sat, Aug 15, 2026
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Start with invoices or sales completed during the period. Deduct refunds, returns and cancelled sales. If you charge VAT, calculate performance using amounts before VAT and keep the tax collected separate from business revenue.
Do not count every credit alert as a sale. Remove:
loans received
money you put into the business yourself
transfers between your own accounts
customer deposits for work that has not yet been delivered, if you are using an earned-sales view
Keep a second number beside sales: how much of it customers still owe. That outstanding amount can be part of earned revenue while still being unavailable as cash.
Step 3: Calculate the cost of what you sold
For a product business, do not subtract every item you bought during the month. Unsold goods are still stock. The cost becomes an expense when the related item is sold, which is why a closing stock count matters.
Cost of goods sold = Opening stock + Purchases + Direct purchase costs − Closing stock
Direct purchase costs can include transport, clearing, packaging or handling needed to bring the goods to a sellable condition. Use cost price, not the price on the shelf. The IFRS Foundation’s inventory guidance follows the same matching principle: the carrying cost of inventory is recognised as an expense when the inventory is sold.
For a service business, replace stock cost with the direct cost of delivering the work: project materials, subcontractors, production labour or software bought only for that job. General data, rent and administrative salaries belong under operating expenses.
If you are unsure what belongs in one product’s cost, the guide to cost price versus selling price shows how to allocate transport, packaging and other direct costs per unit.
Step 4: Add the costs of running the business
Now total the expenses for the same period. Use records rather than memory, because frequent small costs are often the difference between an apparent profit and a real one.
shop or office rent for the period
staff salaries and wages not already counted as direct labour
electricity, fuel, internet and phone data
marketing, commissions and customer delivery
payment-processing fees and bank charges
repairs, subscriptions, professional fees and other running costs
A consistent expense-tracking routine makes this step faster and reduces the chance of a profit figure that is too high because some costs were forgotten.
Worked example: a small retail business
A retailer is reviewing one month. Sales delivered during the month were ₦2,400,000. Customers have paid ₦2,000,000, so ₦400,000 is still outstanding. The profit calculation uses the ₦2,400,000 earned-sales figure and keeps the ₦400,000 receivable visible beside it.
1. Work out cost of goods sold
Opening stock: ₦850,000
Purchases: ₦1,100,000
Transport to bring those purchases in: ₦100,000
Closing stock: ₦650,000
Cost of goods sold = ₦850,000 + ₦1,100,000 + ₦100,000 − ₦650,000 = ₦1,400,000
The business made an estimated operating profit of ₦300,000 for the month. That does not mean ₦300,000 is sitting in the bank. Customers still owe ₦400,000, and ₦650,000 is tied up in closing stock. Profit, receivables and stock answer different questions, so keep all three visible.
A design studio delivers ₦1,200,000 of work in a month. Subcontractors and project-specific materials cost ₦300,000, leaving ₦900,000 gross profit. Rent, salaries, software, data and marketing total ₦420,000.
A service business may have little or no stock, but the principle is the same: separate the direct cost of delivering the work from the wider cost of keeping the business open.
Five mistakes that make profit look better or worse than it is
Treating stock purchases as cost of sales. Subtract only the cost of items sold in the period. Unsold stock remains stock.
Counting loans or owner funding as sales. They increase cash, but they do not mean the business earned revenue.
Treating loan principal or owner withdrawals as operating expenses. They reduce cash but do not measure the cost of making sales. Interest and bank charges are separate costs.
Forgetting refunds, fees and small expenses. Each one looks minor; together they can change the decision you make about pricing or spending.
Comparing profit calculated on different rules. A cash-basis January cannot be compared cleanly with an earned-sales February. Keep the period and method consistent.
Why sales can rise while profit falls
More sales do not guarantee more profit. Supplier costs may have risen, discounts may have widened, delivery may be absorbing the margin, or extra staff and marketing may be growing faster than revenue. Compare the components, not only the final number.
Gross profit falling points first to pricing, discounts or direct cost.
Gross profit holding while operating profit falls points to overheads.
Profit holding while cash falls points to unpaid invoices, stock or other cash movements.
For product lines that are not moving, review the guide to finding and clearing dead stock. Stock that does not sell can consume cash even before it changes the profit calculation.
A monthly small-business profit checklist
Choose one month and write down whether you are using earned sales or cash collected.
Total sales, then remove refunds, cancelled sales and non-sales bank credits.
Count closing stock and calculate the cost of goods sold, or total direct project costs for services.
Add every operating expense for the same period, including fees and small recurring costs.
Calculate gross profit, estimated operating profit and profit margin.
Write unpaid invoices and closing stock value beside the profit figure so cash constraints stay visible.
Compare the result with the previous three months and investigate the line that moved most.
Keep the inputs where you can use them
A profit formula only works when the sales, costs and expenses behind it are complete. If those numbers live across bank alerts, supplier chats and a notebook, the monthly calculation becomes a reconstruction exercise.
WadMaster keeps invoices, recorded expenses and inventory costs connected. Its inventory workflow records what products cost and what is left, while invoices and expense records supply the other side of the calculation. That gives you a repeatable way to know what you sold, what it cost you, who still owes you and what the business actually made.
Put this guide into practice
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