Managing inventory well comes down to three things: knowing what you have, knowing when to order more, and knowing which products deserve your attention.
Everything below serves one of those. If you are starting from a spreadsheet and a strong suspicion that the numbers are wrong, work through the steps in order — each depends on the one before it. If you already have a system running, the later steps are where the improvements usually are.
Step 1: Count what you actually have
Every other step assumes your records are right. If they are not, you will be calculating reorder points from fiction.
Do a full physical count before you change anything else. Count by location rather than by product total — a SKU can reconcile perfectly overall whilst being wrong in two places that cancel out, and those two places will still generate failed picks.
A few things that make a count worth the disruption:
- Freeze movement whilst counting, or count outside operating hours. Counting a moving target produces numbers nobody trusts.
- Count blind. Do not show the counter the expected figure. People unconsciously confirm what they are shown.
- Recount discrepancies before adjusting. The second count is right more often than the first.
- Record the reason for significant variances. The pattern in those reasons is where your process problems are.
This is the most disruptive thing in this guide and the step people most often skip. Skipping it means everything afterwards inherits the error.
Step 2: Choose where your stock lives — and organise it
Give every item a defined home, and label it.
Fixed locations mean each product always lives in the same place. Easy to learn, easy to audit, and wasteful of space because the location sits empty when stock is low.
Random or dynamic locations mean the system assigns whatever space is free and records where it went. Far better space utilisation, and completely dependent on the system being right, because nobody can find anything by memory.
Most operations run a hybrid: fixed pick faces for fast movers, dynamic locations for reserve stock.
Whichever you choose:
- Label locations clearly and consistently. A logical scheme — aisle, bay, level, position — beats a historical one that only long-serving staff can decode.
- Put fast movers near dispatch. Travel time is the largest component of picking labour, and a handful of products usually account for most of the movement.
- Keep heavy items at waist height. Safety and speed both improve.
- Separate goods-in, quarantine and returns from sellable stock. Mixing them is how unchecked stock gets sold.
Step 3: Pick a system to track stock
Spreadsheets work up to a point, and that point arrives sooner than most people expect — usually when you start selling through more than one channel, or when more than one person updates the file.
What a proper system gives you that a spreadsheet does not:
- A single live figure across every channel, so you cannot oversell.
- Barcode scanning, which removes the transcription errors that cause most discrepancies.
- Transaction history, so you can see how a number became wrong rather than only that it is.
- Reorder alerts that fire without anyone remembering to look.
- Batch, serial and expiry tracking, which is close to impossible to maintain manually.
You do not need an expensive system to start. You do need one where the warehouse can update stock at the point the movement happens, rather than writing it down to enter later. Deferred data entry is where accuracy goes.
Step 4: Set reorder points and safety stock
A reorder point is the level that triggers a new order. Get it right and stock arrives just as you need it.
Reorder point = (average daily usage x lead time in days) + safety stock
Safety stock is the buffer absorbing the fact that demand and lead times both vary. A reasonable starting formula:
Safety stock = service factor x standard deviation of demand x square root of lead time
Two practical points that matter more than the arithmetic.
Use measured lead times, not quoted ones. What the supplier promises and what they deliver are different numbers, and the spread between their fastest and slowest delivery matters more than the average.
Vary service levels by product. A single target across the whole range guarantees you hold too much of the slow lines and too little of the critical ones.
Step 5: Focus your effort with ABC analysis
You cannot manage every product with equal attention, and you should not try.
ABC analysis sorts products by their share of annual consumption value:
- A items — roughly the top 20% of products, typically 70–80% of value. Tight control, frequent review, high service levels, frequent counting.
- B items — the middle band. Moderate control, periodic review.
- C items — the long tail, usually half your products and a small share of value. Loose control, larger order quantities, infrequent counting.
The point is not the classification. It is that your time goes where the money is. Most operations discover they have been giving equal attention to a $50,000 line and a $200 line.
Worth adding a second dimension: criticality. A cheap component that halts production when missing deserves A-item treatment regardless of its value.
Step 6: Keep records accurate with cycle counting
After the initial full count, do not wait a year to count again.
Cycle counting counts a small portion of stock continuously — a few locations daily — so the whole site gets covered over a period without ever shutting down. Count A items most often, C items least.
Its real benefit is not the correction. It is that errors surface within days rather than months, close enough to their cause that you can actually find out what went wrong. A discrepancy found eleven months later is a number to adjust; one found on Tuesday is a process problem you can fix.
Track your inventory record accuracy as a percentage of locations matching exactly, and watch the trend.
Step 7: Watch the right numbers
Four metrics will tell you most of what you need:
- Inventory record accuracy — locations matching exactly, as a percentage.
- Inventory turnover — cost of goods sold divided by average inventory value. How hard your capital is working.
- Stockout rate or fill rate — how often you fail to supply from stock.
- Dead stock — the value of inventory with no movement over a defined period.
Read them together. High turnover with a high stockout rate means you are running too lean. Low turnover with no stockouts means you are holding too much.
Compare against your own history rather than published benchmarks, which come from operations with different products and order profiles.
Step 8: Review, learn and tighten
Set a recurring review. Monthly is enough for most operations.
- Re-run ABC. Products move between classes as demand shifts.
- Recalculate reorder points and safety stock against recent demand and actual lead times.
- Review dead and slow-moving stock and decide: discount, bundle, return to supplier or write off. Deciding nothing is itself a decision, and an expensive one.
- Look at the discrepancy reasons from cycle counts for patterns.
- Check supplier performance — on-time delivery and order accuracy per supplier. A supplier whose reliability has quietly deteriorated is inflating your safety stock requirement.
Common mistakes to avoid
Managing from the office. Numbers describe the warehouse; they are not the warehouse. Walk it.
Treating the system as the truth. The system holds what it was told. Counting is what tells you whether it was told correctly.
Ordering by feel. Reorder points exist so that ordering is not a judgement call made by whoever noticed the shelf looked empty.
Letting dead stock accumulate. It costs storage, ties up capital, and gets harder to shift the longer it sits.
Chasing perfect accuracy everywhere. The last few percentage points of service and accuracy cost disproportionately. Spend them on A items.
Changing several things at once. If you adjust reorder points, relayout the pick face and switch systems in the same month, you will not know which change caused what.
Where to go deeper
- What is inventory management — the discipline in full.
- What is inventory control — the narrower operational side.
- Inventory management techniques — specific methods in more detail.
- What is a reorder point — the trigger calculation.
- What is safety stock — sizing the buffer.
- Cycle counting — keeping records accurate.
- What is inventory turnover — the efficiency measure.
The one-line takeaway
Count what you have, give everything a labelled home, track it in a system the warehouse updates in real time, set reorder points from measured lead times, concentrate your attention on the products that carry the value, and count continuously so errors surface whilst you can still find the cause.
Frequently asked questions
Where do I start with inventory management? A full physical count by location. Every other step calculates from your stock records, so they need to be right before anything else is worth doing.
What is the best inventory management method? There is no single best. Most operations combine reorder points with ABC analysis and cycle counting. The method matters less than applying it consistently and reviewing it as demand changes.
How often should I count stock? Continuously, through cycle counting, rather than once a year. Count A items monthly or more, B items quarterly, C items once or twice a year. Full annual counts are increasingly used only where an auditor requires one.
Do I need inventory management software? Not at very small scale, but spreadsheets break down quickly once you sell through multiple channels or more than one person maintains the file. The decisive features are a single live stock figure and scanning at the point of movement.
How do I stop running out of stock? Set reorder points from measured lead times and add safety stock sized to your actual demand variability. Then make sure someone acts on the alerts, because most stockouts in operations that have reorder points happen because nobody ordered.
How much inventory should I hold? Enough to meet your target service level given how variable your demand and lead times are, and no more. That figure differs per product, which is why a single blanket rule of “a month’s cover” over-invests in some lines and under-invests in others.
How do I know if my inventory records are accurate? Count a sample of locations and compare against the system. Inventory record accuracy is the percentage of locations matching exactly. Counting by location rather than by product total is what matters — totals can reconcile whilst individual locations are wrong in offsetting directions.
What is dead stock and what should I do with it? Inventory with no movement over a defined period. Discount it, bundle it, return it to the supplier if the agreement allows, or write it off. The mistake is leaving it, because it consumes space and capital and loses value whilst you decide.
Warehouse Wise is a free, independent library of guides on inventory management, warehousing and fulfilment, written for the people actually doing the work — new warehouse and inventory staff, small and growing retail and ecommerce businesses, and anyone who holds stock and wants to understand it properly. Every guide explains the term, shows a worked example with real numbers where it helps, and stops. We are independent: we do not sell software or equipment, we take no commission on referrals, and our guides are not ranked by who pays us.