How to Calculate Profit and Loss for Your Small Business

What Is Profit and Loss?

Let us start with the basics. Profit and loss (P&L) tells you one simple thing: did your business make money or lose money?

Many shop owners in Nigeria know they are busy. Customers come in, money changes hands, stock moves. But at the end of the month, the question is always the same: “Where did all the money go?”

That is what profit and loss calculation answers. It shows you exactly how much money came in, how much went out, and what is left for you.

Revenue Is Not Profit

This is the number one mistake Nigerian business owners make. Revenue is all the money that comes into your shop. Profit is what remains after you pay for everything.

Here is an example. Say you sell bags of rice in your shop.

• You buy one bag of rice for ₦75,000 (as of 2026)
• You sell it for ₦85,000
• Your revenue is ₦85,000
• Your cost is ₦75,000
• Your gross profit on that bag is ₦10,000

But wait. That ₦10,000 is not your final profit. You still have other costs to pay. We will get to that shortly.

The point is simple: just because ₦85,000 entered your account does not mean you made ₦85,000. Many people confuse revenue with profit and think they are doing well when they are actually losing money.

The Three Types of Profit You Need to Know

1. Gross Profit

Gross profit is what you get when you subtract the cost of goods from your revenue. It only looks at the direct cost of the things you sold.

Gross Profit = Revenue - Cost of Goods Sold

If you sold ₦500,000 worth of goods this month and those goods cost you ₦350,000 to buy, your gross profit is ₦150,000.

2. Operating Profit

Operating profit goes deeper. It subtracts your running costs from your gross profit. Running costs include rent, transport, staff salary, electricity (generator fuel!), and other expenses you pay to keep the shop open.

Operating Profit = Gross Profit - Operating Expenses

Using our example above:

• Gross Profit: ₦150,000
• Rent: ₦40,000
• Generator fuel: ₦25,000
• Staff salary: ₦35,000
• Transport: ₦15,000
• Phone and data: ₦5,000
• Total expenses: ₦120,000

Operating Profit: ₦150,000 - ₦120,000 = ₦30,000

See how ₦500,000 in revenue became ₦30,000 in real profit? This is why tracking your expenses matters.

3. Net Profit

Net profit is the final number after everything, including taxes, loan repayments, and any other costs. For most small businesses, operating profit and net profit are close. But if you have a loan or pay taxes, net profit will be lower.

Step-by-Step: Calculate Your Monthly Profit and Loss

Here is a simple method any shop owner can follow. You do not need an accounting degree. You just need to be honest with your numbers.

Step 1: Add Up All Your Sales (Revenue)

Write down every sale you made during the month. If you use a POS machine, check your POS reports too. Add cash sales and POS sales together.

Example for January:

• Week 1: ₦125,000
• Week 2: ₦140,000
• Week 3: ₦110,000
• Week 4: ₦135,000
• Total Revenue: ₦510,000

Step 2: Calculate Your Cost of Goods Sold

This is the total amount you spent to buy the things you sold. Not the things sitting on your shelf. Only the things that actually left your shop.

One simple way to calculate this:

Cost of Goods Sold = Opening Stock + Purchases - Closing Stock

If you had ₦200,000 worth of goods at the start of the month, you bought ₦300,000 more, and you have ₦180,000 left at the end:

COGS = ₦200,000 + ₦300,000 - ₦180,000 = ₦320,000

This is why regular stock-taking matters. Without it, you cannot know your true cost.

Step 3: Subtract to Get Gross Profit

₦510,000 - ₦320,000 = ₦190,000 Gross Profit

Step 4: List All Your Expenses

Write down every single thing you spent money on to run the business. People often forget some costs. Here are common ones Nigerian shop owners miss:

Step 5: Calculate Your Net Profit

₦190,000 - ₦155,000 = ₦35,000 Net Profit

So from ₦510,000 in sales, this shop owner made ₦35,000 in real profit. That is about 6.9% profit margin.

Common Mistakes That Kill Your Profit

1. Not Counting Rent as a Cost

Some people think, “I already paid rent, so it is not part of my business cost.” Wrong. Rent is one of your biggest expenses. If your shop does not generate enough profit to cover rent, your business is losing money.

2. Forgetting Transport Costs

The money you spend going to the market to buy stock is a business cost. The okada or bus fare, the danfo to Mile 12 or Alaba market — all of that counts. Many people ignore this and wonder why their profit is low.

3. “Eating From the Business”

This one is very common. You take ₦2,000 here for lunch, ₦5,000 there for your child’s school fees, ₦3,000 for data. By the end of the month, you have taken ₦50,000 or more from the business without recording it.

That money is not free. It is either your salary (which should be planned) or it is reducing your profit. Either way, you need to separate your business money from personal money. E no good to dip hand inside business money anyhow.

4. Ignoring Wastage and Theft

Expired products, damaged goods, items that went missing — these are real costs. If you do not track them, your profit calculation will be wrong. You will think you are making money when you are not.

5. Not Tracking Daily

If you wait until the end of the month to count everything, you will miss things. Track your sales and expenses every day. Even if it is just five minutes before you close. Better still, use an app that does it for you as you sell.

A Simple Monthly P&L Template

You can use this format in a notebook or on your phone:

=== PROFIT AND LOSS: [MONTH] ===

REVENUE
  Total Sales:           ₦_________

COST OF GOODS SOLD
  Opening Stock:         ₦_________
  + Purchases:           ₦_________
  - Closing Stock:       ₦_________
  = Cost of Goods:       ₦_________

GROSS PROFIT:            ₦_________

EXPENSES
  Rent:                  ₦_________
  Fuel / Power:          ₦_________
  Staff:                 ₦_________
  Transport:             ₦_________
  Phone / Data:          ₦_________
  Packaging:             ₦_________
  Other:                 ₦_________
  Total Expenses:        ₦_________

NET PROFIT:              ₦_________

Fill this in at the end of every month. Compare it to previous months. Are your costs going up? Is your profit margin shrinking? This simple exercise gives you power over your business.

What Is a Good Profit Margin?

For most Nigerian retail businesses, a healthy profit margin is between 10% and 25%. Here is a rough guide:

If your margin is below 10%, you need to either increase prices, reduce costs, or find higher-margin products to sell. Knowing your numbers is the first step.

How Often Should You Calculate P&L?

At minimum, do it monthly. But weekly is even better for small businesses. The more often you check, the faster you can spot problems and fix them.

Some business owners only realize they are losing money at the end of the year. By then, it is too late. A monthly review takes less than 30 minutes and can save your business.

Let Technology Do the Math

Calculating profit and loss by hand works, but it takes time and you can make mistakes. Modern business apps can track your sales, costs, and expenses in real-time. Every time you record a sale or expense, your profit updates automatically.

SabiBooks calculates your daily profit automatically. You record a sale, it updates. You record an expense, it updates. At any point in the day, you can see exactly how your business is doing. No calculator needed.

Key Takeaways

1. Revenue is not profit. Always subtract your costs before celebrating.
2. Track every expense. Rent, fuel, transport, packaging — everything counts.
3. Stop eating from the business. Give yourself a fixed salary instead.
4. Do stock-taking regularly. You need closing stock numbers for accurate P&L.
5. Calculate monthly at minimum. Weekly is even better.
6. Know your margin. If it is below 10%, something needs to change.

Your business na your future. When you know your numbers, nobody fit cheat you. You go always know where you stand.

Want to learn more about managing your business finances? Read our guide on separating business money from personal money or learn how to do stock-taking without closing your shop.