How to Record Stock Purchases: A Guide for Kenyan Retailers

You just came back from the wholesaler. The back of your car has a 50 KG bag of sugar, a crate of Coca-Cola, a jerrycan of cooking oil, and five trays of eggs. Now you need to enter all of this into your inventory system.

If you have ever stared at a screen wondering "what number do I put where?" — this guide is for you.

The Only Formula You Need

Every stock purchase comes down to one simple calculation:

Total cost divided by total quantity equals unit cost.

That is it. Whether you bought a bag, a crate, a jerrycan, or a tray — the math is the same. You just need to know how many base units you received and what each one cost.

For example, a 50 KG bag of sugar for KES 6,500:

Quantity: 50 (kilograms)
Unit cost: 6,500 divided by 50 = KES 130 per kilogram

The bag is just packaging. Your system tracks 50 kilograms at 130 each.

Bags and Sacks (Bulk Weight)

This is the most common scenario for dukas and agrovets. You buy goods in large bags and sell them in smaller quantities.

A 50 KG bag of sugar for KES 6,500:

Enter quantity: 50
Enter unit cost: 130 (that is 6,500 divided by 50)
Your stock increases by 50 KG

A 25 KG bag of rice for KES 3,750:

Enter quantity: 25
Enter unit cost: 150
Your stock increases by 25 KG

A 50 KG bag of maize flour for KES 5,000:

Enter quantity: 50
Enter unit cost: 100
Your stock increases by 50 KG

The bag, sack, or bale is not the item. It is just how the supplier delivered it. Your inventory tracks the contents in the base unit — kilograms.

Jerrycans and Drums (Bulk Liquid)

Same principle, different product. You buy liquids in large containers and sell in smaller quantities.

A 20-litre jerrycan of cooking oil for KES 4,000:

Enter quantity: 20
Enter unit cost: 200 (that is 4,000 divided by 20)
Your stock increases by 20 litres

A 200-litre drum of paraffin for KES 30,000:

Enter quantity: 200
Enter unit cost: 150
Your stock increases by 200 litres

The jerrycan is just the container. Your inventory tracks litres.

Cartons and Crates (Pre-Packed Items)

When you buy pre-packed items — bottles, packets, bars — you receive a certain number of pieces. The carton or crate is just the outer packaging.

A crate of 24 Coca-Cola 500ml for KES 840:

Enter quantity: 24
Enter unit cost: 35 (that is 840 divided by 24)
Your stock increases by 24 pieces

A carton of 72 bar soaps for KES 2,880:

Enter quantity: 72
Enter unit cost: 40
Your stock increases by 72 pieces

A carton of 12 Elianto 1L bottles for KES 2,400:

Enter quantity: 12
Enter unit cost: 200
Your stock increases by 12 pieces

A bale of 12 Jogoo 2kg packets for KES 2,280:

Enter quantity: 12
Enter unit cost: 190
Your stock increases by 12 pieces

A carton of 24 Omo 500g sachets for KES 2,160:

Enter quantity: 24
Enter unit cost: 90
Your stock increases by 24 pieces

Notice that Elianto 1L is "1 litre" but the unit is pieces, not litres. You sell the sealed bottle — you do not pour 1 litre from it. Same with Jogoo 2kg — you sell the packet, not 2 kilograms of flour.

Trays and Dozens

A tray of 30 eggs for KES 510:

Enter quantity: 30
Enter unit cost: 17 (that is 510 divided by 30)
Your stock increases by 30 pieces

5 trays of eggs for KES 2,400 (bulk discount):

Enter quantity: 150 (that is 5 times 30)
Enter unit cost: 16 (that is 2,400 divided by 150)
Your stock increases by 150 pieces

A dozen Geisha soap for KES 720:

Enter quantity: 12
Enter unit cost: 60
Your stock increases by 12 pieces

Rolls and Coils (Length)

For hardware stores, this is common.

A 100-metre roll of nylon rope for KES 3,000:

Enter quantity: 100
Enter unit cost: 30 (that is 3,000 divided by 100)
Your stock increases by 100 metres

A 25 KG roll of binding wire for KES 3,750:

Enter quantity: 25
Enter unit cost: 150
Your stock increases by 25 KG

Items You Buy Individually

Some things you buy one at a time or in small numbers. The math is even simpler.

20 loaves of bread for KES 1,040:

Enter quantity: 20
Enter unit cost: 52

5 K-Gas 6kg refills for KES 3,750:

Enter quantity: 5
Enter unit cost: 750

10 bags of cement for KES 7,500:

Enter quantity: 10
Enter unit cost: 750

Remember — cement bags are sold whole. Nobody buys 23 kilograms of cement. The unit is pieces (bags), not kilograms.

Multiple Items in One Trip

You do not need to create a separate entry for each item. Record everything from one trip together:

Trip to Ngong Wholesalers, 15 February:

Sugar — 50 KG at KES 130/KG
Bar Soap — 72 pieces at KES 40 each
Cooking Oil — 20 litres at KES 200/L
Eggs — 30 pieces at KES 17 each
Bread — 20 pieces at KES 52 each

Total: KES 15,100. One receipt, five line items. All stock levels update at once.

What About Price Changes?

Sugar costs KES 6,500 this week but KES 7,000 next week. Just record each delivery as it happened:

1 February: Received 50 KG at KES 130/KG
15 February: Received 50 KG at KES 140/KG

Your system tracks the weighted average cost automatically. You do not need to recalculate anything manually.

The Quick Reference Table

You bought	Quantity to enter	Unit cost formula
50 KG bag for KES X	50	X divided by 50
25 KG bag for KES X	25	X divided by 25
20L jerrycan for KES X	20	X divided by 20
Carton of N pieces for KES X	N	X divided by N
Tray of 30 for KES X	30	X divided by 30
Roll of N metres for KES X	N	X divided by N
N individual items for KES X	N	X divided by N

Every purchase, same formula: total cost divided by total quantity. Once you see the pattern, it takes five seconds per item.

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