Gross Profit vs Net Profit for a Small Shop: Counting from Purchase Price, Shrinkage, and Daily Costs

Many small shop owners work out profit with one rough formula: money in minus money out. It is fast, but it often lies. A busy shop can look very profitable while the cash has already gone on spoiled stock and daily costs that were never written down. The fix is to keep gross profit and net profit apart.

This article uses a simple grocery shop example, so you can copy the method directly. All figures are illustrations; replace them with your own.

Gross profit versus net profit

Gross profit is sales minus the cost of goods sold (COGS). COGS is the money tied up in goods that were actually sold, including goods lost to shrinkage. Gross profit has not yet paid for operating costs such as rent, electricity, transport and wages.

Net profit is gross profit minus all operating costs. This is what the business truly keeps, before tax and before you take money out for yourself.

The most common mistake is calling gross profit "the profit". Gross profit still has to cover every daily cost. Many shops post a healthy gross profit but a thin net profit because daily costs grew without anyone noticing.

Start from the purchase price: gross profit per unit

Take one product, for example bottled cooking oil. You buy one carton of 12 pouches for Rp168,000. The purchase price per pouch is therefore Rp14,000.

If you sell at Rp20,000 per pouch, gross profit per pouch is Rp6,000. As a percentage, the gross margin is gross profit divided by the selling price, which is 30%.

The margin figure helps you compare products. Two products can give the same rupiah profit but very different margins. A thin-margin product is far more sensitive when the purchase price rises a little.

If you are not yet sure about your cost or price, read how to calculate unit cost and price first.

Shrinkage: the cost that never shows on a receipt

Shrinkage is stock you paid for but cannot sell: broken, leaking, expired, lost or spilled. The money has already left the till, so shrinkage belongs in the cost of goods.

Continue the example: of the 12 pouches, 2 leak, so only 10 can be sold. The Rp168,000 must now be carried by 10 pouches, so the effective cost becomes Rp16,800 per pouch instead of Rp14,000.

If the selling price stays at Rp20,000, gross profit per pouch falls to Rp3,200 and the gross margin drops to 16%. A small amount of shrinkage can eat a large share of the margin.

Record shrinkage every day in your daily sales book, so at month end you work from real figures rather than a guess.

Daily costs: from small spending to a monthly figure

Daily costs feel trivial because they are small and frequent: plastic bags, ice, electricity, transport, even staff meals. If you do not record them, they vanish from the arithmetic and profit looks bigger than it is.

A practical method: record every small expense for one month, then divide by 30 days to see the average daily cost. Our grocery example:

• Shop rent: Rp2,000,000 per month
• One employee's wages: Rp2,500,000 per month
• Electricity and water: Rp500,000 per month
• Restocking transport: Rp600,000 per month
• Plastic bags and supplies: Rp400,000 per month

Total operating costs are Rp6,000,000 per month, or about Rp200,000 per day.

A one-month summary: the grocery shop

Suppose monthly sales are Rp40,000,000. The cost of goods actually sold is Rp26,000,000, plus Rp2,000,000 of shrinkage, so COGS becomes Rp28,000,000. The result:

• Sales: Rp40,000,000
• COGS: less Rp28,000,000
• Gross profit: Rp12,000,000 (gross margin 30%)
• Operating costs: less Rp6,000,000
• Net profit: Rp6,000,000 (net margin 15%)

Notice that a gross profit of Rp12,000,000 looks large, but after daily costs only Rp6,000,000 is left. If shrinkage or overhead rises without a price increase, net profit can disappear altogether.

This explains the busy-but-not-profitable shop: sales are strong, but the gross margin is thin and daily costs are not under control.

Practical steps to work out your shop's profit

• 1. Collect one month of purchase receipts and total the purchases.
• 2. Value opening and closing stock to find the cost of goods actually sold.
• 3. Write down the month's shrinkage (broken, expired, lost) and add it to COGS.
• 4. Add up monthly sales from your daily records.
• 5. Gross profit = sales minus COGS.
• 6. Add up all daily costs for the month, then subtract them from gross profit.
• 7. The result is net profit. Compare it with the previous month.

If this feels long, the pricing and margin calculator works out cost, margin and selling price automatically, so you only need to enter the purchase price and shrinkage.

Common mistakes when counting shop profit

• Counting profit without separating goods still unsold, so stock is treated as already earned.
• Forgetting shrinkage because there is no receipt for it.
• Mixing business and personal money; see how to separate business and personal money.
• Treating the cash balance as profit.
• Working it out at month end from memory instead of daily records.

When you need an accountant

For a small shop, the method above is usually enough. Consider an accountant when stock is large and changes often, when you are applying for a bank loan, when you run several branches, or when you start employing permanent staff with payroll deductions.

Tax also deserves a check. For individual (personal) MSME taxpayers, turnover up to Rp500,000,000 a year is not subject to the final income tax, while the portion above it is subject to a final 0.5% rate. A simple illustration: with annual turnover of Rp600,000,000, the final tax is about Rp500,000. These figures are an illustration, not tax advice, and the rules can change, so always check the official source before paying.

Keeping gross and net profit up to date makes tax and loan applications far easier, because you have figures you can stand behind.

Start with this month

You do not need a complicated system. Start by recording daily sales, calculating COGS including shrinkage, then separating daily costs. After one month you will see for yourself where the money really goes.

To move faster, use the pricing and margin calculator and read how to build small business financial statements so your daily numbers turn straight into a monthly report.

Frequently asked questions

What is the difference between gross and net profit?

Gross profit is sales minus the cost of goods sold. Net profit is gross profit minus all operating costs. Gross profit shows how efficient your pricing is; net profit shows what is actually left for the owner.

Should shrinkage be part of COGS?

Yes. Shrinkage is stock you already paid for but cannot sell, so its value is part of the cost of goods. Keeping shrinkage as a separate cost line is also fine, as long as it is still subtracted from profit.

What if I do not record every day?

Records rebuilt from memory are almost always wrong on COGS and stock. Start recording sales and shrinkage daily; a small consistent habit is more useful than a complete report that arrives late.

What gross margin is normal for a shop?

It depends on the product. Basic necessities usually carry thin margins, while snacks and drinks carry more. What matters is not the number itself but whether the gross margin covers daily costs and still leaves a net profit.

When is a shop's profit healthy?

When net profit stays positive after all costs, including paying the owner, and is not wiped out by shrinkage. If net profit stays thin, check your selling price, purchase price and shrinkage before trying to sell more.