Weighted Average Cost: The Honest Margin Behind Every Price

The pain: which cost is the real cost?

Every shop owner in Nigeria has lived this story. You bought a carton of indomie at ₦11,000 in January. In February the supplier says ₦11,500. By April it is ₦12,200. Meanwhile you are still selling sachets at ₦350 because that is what the street expects, and somewhere in the middle your profit quietly changed shape.

Now the hard question: when you sell a sachet today, what did that sachet cost you? The January price? The April price? Some shops use the oldest price and feel richer than they are. Some use the newest price and cannot explain where the money went. Most use no price at all and simply hope.

This is not a small bookkeeping detail. Pricing decisions, restock decisions and the answer to "is this shop actually making money" all sit on top of one number: the true cost of what left the shelf. Get it wrong and every other figure is decoration.

What weighted-average cost is

Gazeloft's retail engine uses weighted-average cost of goods sold. In plain words: every time you restock a product, the app blends the new purchase into what you already had, weighted by quantity, and produces one honest average cost per unit. Every sale from that moment uses the updated average.

The formula is simple:

New average cost = (value of old stock + value of new stock) divided by (old quantity + new quantity)

You never calculate it yourself. You just record the restock with its quantity and what you paid, and Gazeloft does the blending. The result is a cost figure that reflects what your shelf really cost you across every price change, not the price you remember from a good month.

Step by step: in the app

1. Open your retail space and go to the product, for example Indomie sachet.
2. Tap to restock. Enter the quantity you bought and the total or unit cost you actually paid this time.
3. Save. Gazeloft recalculates the weighted-average cost instantly. You can see the updated cost on the product.
4. Sell as normal through the cart. Every basket's profit now uses the fresh average automatically. There is nothing to switch on and nothing to remember.

Step by step: on the web dashboard

1. Log in at gazeloft.com and open the retail space.
2. In the products area, find the product and record the restock with quantity and cost, exactly as in the app.
3. Review your margins in the shelf insights. The margin alarm card will flag any product now selling below a healthy margin, which is exactly what happens when supplier prices climb and shelf prices sleep.

A worked example: the indomie squeeze

Follow one product through three months at Mama Chidi's shop. She sells sachets at ₦350 throughout.

January. She buys 3 cartons at ₦11,000 each, 40 sachets per carton: 120 sachets at ₦275 each. Average cost: ₦275. Margin per sachet: ₦75.

February. With 40 sachets left on the shelf (value ₦11,000 at the old average), she buys 3 more cartons at ₦11,500 each: 120 sachets costing ₦34,500, which is ₦287.50 per sachet.

New average = (₦11,000 + ₦34,500) divided by (40 + 120) = ₦45,500 divided by 160 = ₦284.38 per sachet.

Margin per sachet is now ₦65.62. Not the ₦75 of January, not the ₦62.50 the new carton alone would suggest, but the honest blend of what is truly on her shelf.

April. With 30 sachets left, she buys 3 cartons at ₦12,200 each: 120 sachets at ₦305 each.

New average = (30 × ₦284.38 + 120 × ₦305) divided by 150 = (₦8,531 + ₦36,600) divided by 150 = ₦300.87 per sachet.

Her margin has quietly fallen from ₦75 to ₦49.13 per sachet, a drop of more than a third, while the shelf price never moved. Without weighted-average cost she would still be mentally banking ₦75 a sachet and wondering why the cash never matches the feeling. With it, the margin alarm card raises its hand: indomie is selling below a healthy margin. She raises the price to ₦400, or negotiates harder with the supplier, and does it months before the damage compounds.

Why not just use the latest price?

Because the latest price lies in the other direction. If you still hold 100 sachets bought at ₦275 and you cost every sale at ₦305, your books show less profit than reality and you may panic-raise prices your customers did not need to face. Weighted average respects both the old stock you are still selling and the new stock you just paid more for. It is the fairest picture of a shelf built across many purchase prices, which is every real shelf in this economy.

There is also a discipline benefit. Because the number updates itself on every restock, nobody in the shop has to remember to recalculate anything, and nobody can quietly use a flattering cost when reporting the week. The books hold one cost per product, built from receipts, and everyone argues from the same figure. For a shop with staff, that single shared truth is worth as much as the arithmetic.

Tips and pitfalls

• Record every restock, even small top-ups from the open market. A restock that never enters the app never enters your average, and your costs drift away from reality.
• Enter what you actually paid, including the price after bargaining. The average is only as honest as the inputs.
• Check the margin alarm card weekly. It exists precisely to catch products whose average cost has crept up under a sleeping shelf price.
• When a supplier gives a bonus quantity, record the full quantity received against the amount paid. The average will correctly come out lower, and that discount becomes visible profit instead of invisible luck.
• Do not manually edit costs to "what they should be." Let the restock records build the number. If a past restock was entered wrongly, reverse it and enter it correctly.

Price with your eyes open

Every price change your supplier makes is already changing your profit. The only question is whether you can see it. Let Gazeloft blend every restock into one honest cost, and price from facts, not memory. Stop guessing. Start seeing, at gazeloft.com.