Inventory Management Basics
Knowing what you hold, what it cost and what is quietly tying up your cash - the stock disciplines that keep a trading business solvent.
Understanding Inventory Management
For businesses that sell physical products, inventory management can make or break profitability. Too much stock ties up cash; too little means lost sales. Getting it right is both an art and a science.
This guide covers the fundamentals of inventory management for South African SMEs - from basic principles to software options that work in our market.
- Cash Flow: Inventory is cash sitting on shelves. Optimize to free up working capital.
- Customer Service: Stockouts mean lost sales and unhappy customers.
- Profitability: Dead stock, theft, and spoilage eat into margins.
- Tender Readiness: Government contracts often require proof of stock capacity.
Inventory Management Basics
Types of Inventory
Raw Materials
Components used to make products. Manufacturing and production businesses.
Work in Progress (WIP)
Partially completed products. Important for manufacturing tracking.
Finished Goods
Ready-to-sell products. Retail, wholesale, and e-commerce focus here.
MRO (Maintenance, Repair, Operations)
Consumables and supplies. Often overlooked but adds up.
Key Inventory Metrics
| Metric | Formula | What It Tells You |
|---|---|---|
| Inventory Turnover | Cost of Goods Sold ÷ Average Inventory | How fast stock is selling (higher = better) |
| Days of Inventory | 365 ÷ Inventory Turnover | Days stock sits before selling |
| Stock Cover | Current Stock ÷ Average Daily Sales | How many days of sales you can cover |
| Stockout Rate | (Stockout Events ÷ Total Orders) × 100 | How often you run out |
| Carrying Cost | (Storage + Insurance + Shrinkage) ÷ Avg Inventory | Cost to hold inventory (typically 20-30%) |
Inventory Valuation Methods
How you value inventory affects your reported profits and tax obligations. SARS accepts several methods, but you must be consistent.
FIFO (First In, First Out)
What: Oldest inventory is sold first
Effect: In rising prices, shows higher profit (lower COGS)
Best For: Perishables, products with expiry dates, general retail
Most Common: Default choice for most SA businesses
Weighted Average
What: Average cost of all items in stock
Effect: Smooths out price fluctuations
Best For: Commodities, bulk items, when prices fluctuate
Calculation: Total Cost of Inventory ÷ Total Units
Specific Identification
What: Track actual cost of each item
Effect: Most accurate but most complex
Best For: High-value items, vehicles, unique products
Requirement: Requires serial number or unique tracking
Once you choose a method, stick with it. SARS frowns on changing methods to manipulate profits. Document your choice and apply consistently.
Stock Control Systems
Periodic vs Perpetual
Periodic SystemOptional
Count stock manually at intervals (weekly, monthly). Update records after count. Simple but less accurate between counts.
Perpetual SystemOptional
Update stock in real-time with each transaction. Requires software/POS. More accurate, more investment.
- Periodic: Fewer than 100 SKUs, low transaction volume, budget constraints
- Perpetual: Many SKUs, high volume, need real-time visibility, tenders require it
Most growing businesses should aim for perpetual inventory with software support.
ABC Analysis
Not all inventory is equal. Focus attention where it matters:
- A Items (70-80% of value, 10-20% of items): Tight control, frequent counts, careful forecasting
- B Items (15-25% of value, 30% of items): Moderate control, monthly review
- C Items (5% of value, 50% of items): Simple controls, order when low
Example: A spaza shop's A items might be airtime, bread, and milk. C items might be matches and sweets.
Reorder Points & Safety Stock
Reorder Point Formula:
Reorder Point = (Average Daily Sales × Lead Time) + Safety Stock
Example:
- Average daily sales: 10 units
- Supplier lead time: 7 days
- Safety stock: 20 units (buffer for variability)
- Reorder Point: (10 × 7) + 20 = 90 units
When stock hits 90 units, place a new order.
Inventory Software Options
Integrated POS/Inventory Systems
| Software | Monthly Cost | Best For |
|---|---|---|
| Lightspeed | R500 - R2,000 | Retail, multiple locations |
| Vend (Lightspeed) | R1,000 - R2,500 | Retail with Xero integration |
| Square for Retail | R0 - R1,000 | Small retail, simple needs |
| Pilot (SA) | R300 - R800 | SA retail, SARS compliant |
Dedicated Inventory Software
| Software | Monthly Cost | Best For |
|---|---|---|
| Cin7 | R5,000+ | Complex inventory, multi-channel |
| DEAR Inventory | R2,000 - R5,000 | Manufacturing, wholesale |
| Ordoro | R1,500 - R4,000 | E-commerce, dropshipping |
| inFlow | R1,000 - R2,500 | Small wholesale, B2B |
Accounting Software with Inventory
| Software | Inventory Feature | Limitation |
|---|---|---|
| Sage Business Cloud | Basic tracking | Limited for complex needs |
| Xero + add-on | Via integrations | Requires third-party app |
| QuickBooks | Basic tracking | Simple inventory only |
| Pastel | Good for retail | Desktop-based |
If you're using Sage or Xero for accounting, start with their built-in inventory features. Upgrade to dedicated software only when you outgrow it.
Managing Suppliers
Good supplier relationships directly impact inventory performance.
Supplier Selection Criteria
ReliabilityRequired
Do they deliver on time, every time? Track their performance.
QualityRequired
Consistent product quality? Defect rates? Returns policy?
PriceRequired
Competitive pricing? Volume discounts? Payment terms?
Lead TimeOptional
How long from order to delivery? Can they expedite?
B-BBEE StatusOptional
Important if you need preferential procurement points.
Supplier Management Tips
- Pay on time: Reliable payers get priority
- Communicate forecasts: Help them plan for your orders
- Don't single-source: Have backup suppliers for critical items
- Review regularly: Annual supplier reviews keep them sharp
- Negotiate terms: Better payment terms free up cash
Inventory for Tenders
Government and corporate tenders often have specific inventory requirements.
Common Tender Requirements
Stock AvailabilityRequired
Proof you can supply required quantities. Stock lists, supplier letters.
Storage FacilitiesRequired
Adequate warehousing for contract quantities. Photos, lease agreements.
Inventory SystemOptional
Some tenders require documented inventory management procedures.
Track RecordOptional
Previous supply contracts, delivery performance records.
Prepare these documents for supply tenders:
- Current stock list with quantities and values
- Warehouse/storage facility details
- Supplier agreements (especially for large contracts)
- Inventory management policy/procedure
- Historical delivery performance data
Common Inventory Problems
- Shrinkage/Theft: Regular counts, security measures, access controls
- Obsolescence: Clear slow-moving stock before it becomes worthless
- Overstocking: Ties up cash, storage costs, risk of obsolescence
- Stockouts: Lost sales, unhappy customers, emergency orders cost more
- Inaccurate Records: Physical counts don't match system - investigate!
- Poor Forecasting: Use historical data, not gut feel
Reducing Shrinkage
Regular Cycle CountsRequired
Count a portion of inventory regularly, not just annual stocktake.
Access ControlsRequired
Limit who can access stock areas. Sign in/out for high-value items.
CCTVOptional
Cameras deter theft and help identify issues.
Inventory AuditsOptional
Random checks and reconciliations.
Next Steps
Audit Current State
Do a full stock count. Compare to records. Identify discrepancies.
Classify Your Inventory
Do ABC analysis. Focus controls on high-value items.
Set Reorder Points
Calculate reorder points for key items to prevent stockouts.
Choose/Upgrade Software
Implement appropriate inventory tracking for your scale.
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