Inventory & Supply Chain: The Silent Margin Killer Hiding in Your Warehouse

At £10 million in revenue, inventory stops being something you manage in a spreadsheet and starts being the single biggest cash commitment in the business. And it goes wrong in exactly two directions.

Too much stock, and you're bleeding cash. Capital is locked up in products that aren't moving. Warehouse costs climb. Eventually, markdowns become the only way out, destroying the margin you worked to build.

Too little stock, and you're bleeding revenue. Your best sellers go out of stock at the worst possible time during a campaign push, a seasonal peak, or just when organic momentum is building. Every stockout is a lost sale you'll never recover, and often a customer who buys from a competitor instead.

The cruel irony is that most scaling ecom brands are dealing with both at the same time. Overstock on the slow movers, understock on the fast ones. The warehouse is full, but full of the wrong things.

Why It Gets Harder at Scale

At £1-3M, a founder can keep stock levels in their head. They know what's moving, what's arriving, and roughly when they'll need to reorder. At £10M+, that intuition breaks down.

The catalogue is larger. Lead times vary by supplier. Sales velocity fluctuates by season, by channel, by promotion. A product that sells 10 units a day in January might sell 50 a day in November and 2 a day in February. Managing this across hundreds or thousands of SKUs, with supplier lead times of 4-16 weeks, becomes a forecasting problem that can't be solved by gut feel.

And yet, most brands at this stage are still running inventory planning on spreadsheets, or relying on basic reorder points that don't account for trends, seasonality, or the actual rate at which products are selling right now.

The Real Cost of Getting It Wrong

Inventory mistakes are uniquely expensive because they're slow to reveal and slow to fix.

Overstock ties up working capital for months. If you've bought 6 months of stock for a product that's now declining, you won't know for 8-12 weeks. By then, you're sitting on dead inventory that will eventually need to be cleared at a loss. For a £10M brand, it's not unusual for £500K-£1M+ to be locked in slow-moving or dead stock at any given time.

Stockouts are invisible losses. They don't show up in your P&L as a cost, they show up as revenue that never happened. If your top 20 products account for 40% of revenue and one of them goes out of stock for two weeks, that's potentially tens of thousands in lost sales. Worse, if you were running paid ads to that product, you've spent money driving traffic to a page that can't convert.

The cascading effect on marketing. This is the one most teams miss. Your marketing team optimises campaigns toward your best-performing products. If those products go out of stock, the campaigns either waste spend or get paused. When stock returns, the campaigns need to rebuild momentum. Inventory instability doesn't just affect operations, it destabilises your entire acquisition engine.

What Good Looks Like

Strong demand planning at this stage means answering a set of questions that most ecom businesses can't:

How many days of stock do I have for each product? Not based on average sales, but on the actual current sell-through rate. A product might have 500 units in the warehouse, but if it's selling 50 a day, that's 10 days of stock and if your reorder lead time is 6 weeks, you're already too late.

What's at risk of selling out? A clear, prioritised view of products approaching stockout, ranked by revenue impact and lead time urgency. This is the daily operational view your supply chain team needs.

What's at risk of becoming dead stock? The opposite problem, products where weeks of cover is growing, sell-through is declining, and the trajectory suggests they'll need to be cleared. Early identification is everything, because intervention options (promotions, bundling, channel shifts) are far more effective at 12 weeks of cover than at 30.

How does stock health connect to commercial performance? The most sophisticated inventory teams don't just track stock they track stock in the context of profitability. A product with 4 weeks of cover and 60% gross margin needs a very different response than one with 4 weeks of cover and 15% gross margin.

Where Most Teams Get Stuck

The fundamental challenge is that inventory data and commercial data live in different systems. Your warehouse management system knows what you have. Your ecommerce platform knows what's selling. Your finance system knows what it costs. Your marketing platform knows what you're promoting.

But nobody has the combined view. So the demand planner is forecasting off historical orders without understanding margin. The buyer is reordering based on sales volume without seeing the marketing spend that drove those sales. The marketing team is scaling campaigns without knowing stock levels.

The decisions aren't bad because the people are bad. They're bad because the picture is incomplete.

How Dema.AI Solves This

Dema.AI connects inventory data with commercial performance data to give you the combined view that most ecom businesses are missing.

Days of stock based on actual sell-through. Rather than simple averages, Dema calculates stock cover based on current sales velocity, giving you an accurate picture of how long each product will last at the rate it's actually selling. This means your reorder triggers are based on reality, not outdated averages.

Stockout risk identification. Dema flags products that are approaching critical stock levels relative to their lead times and sales velocity. This isn't a static report, it's a dynamic view that updates as sales patterns change, so your supply chain team can prioritise replenishment where it matters most.

Dead stock and overstock visibility. On the other side, Dema identifies products where stock is accumulating faster than it's selling. By connecting this to margin data, you can see not just which products are overstocked, but how much capital is at risk and which products need intervention first.

Inventory meets profitability. This is where Dema's approach becomes genuinely different. Because the platform already calculates product-level profitability — from Gross Profit through to Net Gross Profit 3 — inventory decisions can be made in the context of what each product actually contributes. Replenishment priority isn't just "what's selling fastest" but "what's selling fastest and making the most money."

Stock-aware marketing decisions. When your marketing team can see stock levels alongside performance data, they stop promoting products that are about to sell out and start promoting products that have healthy stock and strong margins. This sounds simple, but the number of brands wasting ad spend driving traffic to low-stock products is staggering.

Forecasting with commercial context. Dema's forecasting capabilities help you project demand forward, giving your buying team the inputs they need for purchase orders that are grounded in data rather than guesswork. When you combine demand forecasts with margin data, you're not just buying what you think you'll sell, you're buying what you think you'll profit from.

The Bottom Line

Inventory is where cash flow lives and dies in ecommerce. At £10M+, the difference between a well-managed stock position and a poorly managed one can easily be a six-figure swing in working capital and margin.

The brands that get this right don't just have better operations, they have better marketing, better margins, and more cash to reinvest in growth. The ones that get it wrong are constantly firefighting stockouts, clearing dead stock at a loss, and wondering why revenue is growing but the bank balance isn't.

Inventory isn't glamorous. But at scale, it's the block that determines whether growth creates value or just creates complexity.