Amazon inventory management is where good brands die slow, expensive deaths.

You run out of stock, lose your Best Seller Rank, and spend months clawing back your ranking. Or you over-order, pay crippling storage fees, and watch your margins evaporate.

Most sellers live in a constant state of inventory panic. Either scrambling to avoid stockouts or scrambling to avoid storage fee bombs.

I'm Andrew Morgans, founder of Marknology. We've managed inventory for over 300 Amazon brands since 2015. We've seen every failure mode: the $47,000 aged inventory fee that nearly bankrupted a client, the stockout during Prime Day that cost $200K in lost sales, the restock limit disaster that left pallets sitting in our warehouse for three months.

We learned the hard way. You don't have to.

This article is the inventory management system we use at Marknology. It's not theoretical. It's the exact process we follow to keep clients in stock, avoid storage fee nightmares, and sleep at night.

If you're tired of inventory firefighting, here's how to fix it.

The Two Inventory Nightmares (And Why They Keep Happening)

Every Amazon seller faces two existential inventory risks:

Nightmare 1: Stockouts You run out of inventory. Your listing goes inactive. Your BSR tanks. Your PPC campaigns stop. Your reviews slow down. Competitors take your market share.

By the time you restock, you've lost months of momentum and thousands in ad spend trying to recover your ranking.

Nightmare 2: Storage Fee Bombs You over-order to avoid stockouts. Now you're sitting on $50,000 worth of inventory in FBA. Amazon starts charging you monthly storage fees. Then aged inventory fees. Then long-term storage fees.

Suddenly, your profit margin goes from 25% to 8% because you're paying Amazon $4,000/month to warehouse slow-moving SKUs.

Both nightmares stem from the same root cause: bad forecasting.

Most sellers guess at reorder quantities based on gut feel, recent sales velocity, or whatever their supplier recommends. They don't account for seasonality, promo impact, restock lead times, or Amazon's constantly changing storage limits.

The result is chaos.

Why Amazon Inventory Management Is Harder Than It Looks

Amazon inventory management isn't just "order more when you're running low."

Here's what you're actually managing:

1. Restock Limits Amazon caps how much inventory you can send to FBA based on your sales velocity and IPI score (Inventory Performance Index).

If your IPI drops below 500, Amazon slashes your limits. Suddenly, you can only send 200 units when you need to send 2,000.

2. Storage Fees Amazon charges monthly storage fees based on cubic feet: - $0.87/cubic foot (Jan-Sept) - $2.40/cubic foot (Oct-Dec, peak season)

If your inventory sits for 271-365 days, Amazon hits you with aged inventory fees ($6.90/cubic foot or $0.15/unit, whichever is greater).

If it sits longer than 365 days, long-term storage fees kick in ($6.90/cubic foot monthly, assessed every month).

3. Seasonal Demand Swings Most products have seasonal patterns. Sunscreen spikes in May. Space heaters spike in November. Planners spike in December.

If you stock linearly, you'll stockout during peak season and drown in storage fees during slow months.

4. Manufacturing Lead Times Most Amazon sellers source from China or overseas. That means: - 30-45 days production time - 30-45 days ocean freight - 7-14 days customs clearance and FBA check-in

You need to reorder 90-120 days before you actually need the inventory.

Miss that window, and you're either paying for air freight (killing margins) or going out of stock (killing BSR).

5. Cash Flow Constraints Inventory ties up cash. If you're doing $100K/month in revenue with 60-day inventory turns, you have $200K sitting in FBA at any given time.

That's $200K you can't use to launch new products, run ads, or pay your team.

Most sellers under-order because they don't have the cash to pre-fund large inventory buys. Then they stockout and lose sales.

Amazon inventory management is a multi-variable optimization problem. Get one variable wrong, and the whole system breaks.

The Marknology Inventory Management System

Here's the system we use to manage inventory for clients doing $50K-$5M/month on Amazon.

Step 1: Calculate True Sales Velocity (Not Amazon's Number) Amazon's "recommended restock quantity" is garbage. It's based on trailing 30-day sales and doesn't account for seasonality, promos, or demand spikes.

We calculate sales velocity using:

Formula: (Units sold in last 90 days) / 90 = Daily sales velocity

• Seasonality: If we're entering peak season, multiply velocity by 1.5-2x
• Promo plans: If we're running a Lightning Deal next month, add expected promo lift
• Trend direction: If sales are accelerating, use last 30-day velocity instead of 90-day

This gives us a realistic daily sales rate.

Step 2: Factor in Total Lead Time Next, we calculate how many days of inventory we need to order.

Total lead time = Production time + Shipping time + Customs + FBA check-in + Safety buffer

• Production: 35 days
• Ocean freight: 40 days
• Customs/FBA: 14 days
• Safety buffer: 21 days (3 weeks)
• Total: 110 days

If we're selling 20 units/day, we need to order at least 2,200 units (20 x 110) to cover the lead time.

Step 3: Add Strategic Overage (But Not Too Much) We add 30-60 days of extra inventory beyond lead time coverage to handle: - Unexpected demand spikes - Supplier delays - Amazon receiving delays - FBA transfer delays between warehouses

But we don't add more than 90 days of overage unless we're entering peak season.

Why? Storage fees.

If you're sitting on 6 months of inventory in FBA during slow season, you're paying Amazon to warehouse product that could sit in a cheaper 3PL.

Step 4: Monitor IPI Score and Restock Limits Weekly Amazon's IPI score determines your restock limits. The score is based on: - Sell-through rate (how fast you move inventory) - Stranded inventory (listings with stock but inactive) - Excess inventory (stock sitting longer than 90 days)

• Remove slow-moving SKUs from FBA
• Fix stranded listings immediately
• Run promos to clear excess inventory

This keeps restock limits high so we can send inventory when we need to.

Step 5: Use a 3PL as a Buffer (The Marknology Advantage) Here's where most sellers get stuck: Amazon restock limits.

Even with perfect forecasting, Amazon might cap your FBA shipment at 500 units when you need to send 2,000.

That's where our 3PL warehouse in Kansas City becomes a strategic weapon.

We receive large inventory shipments from manufacturers at our warehouse. Then we drip-feed inventory into FBA in batches that fit within restock limits.

• Lower storage fees (our warehouse is cheaper than FBA)
• Inventory buffer (we can hold 3-6 months of stock locally)
• Faster restocks (2-day shipment to FBA vs. 45-day ocean freight)
• Multi-channel fulfillment (we can ship DTC, B2B, or TikTok Shop orders from the same inventory)

Most Amazon sellers don't have this infrastructure. They're stuck sending everything to FBA and hoping Amazon doesn't slash their limits.

At Marknology, we treat our 3PL as the strategic reserve. FBA gets 60-90 days of inventory. Our warehouse holds the rest.

Step 6: Seasonal Pre-Positioning (The Q4 Playbook) Q4 is when most sellers either win big or get crushed by storage fees.

Here's our Q4 inventory playbook:

August-September: Start shipping Q4 inventory to our 3PL warehouse. Do NOT send it all to FBA yet (storage fees spike in October).

Late September: Send the first wave to FBA (60 days of inventory, enough to cover Oct-Nov).

Early November: Send the second wave to FBA (enough to cover Black Friday, Cyber Monday, and December).

January: Pull unsold excess inventory out of FBA and back to our warehouse to avoid aged inventory fees.

This strategy keeps storage fees low while ensuring we don't stockout during the highest-revenue months of the year.

Step 7: SKU Rationalization (Cut the Dead Weight) Most Amazon brands have 20-30% of their SKU catalog generating less than 5% of revenue.

These slow-moving SKUs destroy your IPI score and rack up storage fees.

• Is this SKU profitable after storage fees?
• Is this SKU selling at least 10 units/month?
• Is this SKU strategically important (brand positioning, bundle component, gateway product)?

If the answer is no to all three, we liquidate or discontinue it.

Cutting dead SKUs improves IPI, lowers storage fees, and focuses inventory dollars on winners.

Common Inventory Management Mistakes (And How to Avoid Them)

Here are the mistakes we see most often:

Mistake 1: Trusting Amazon's Restock Recommendations Amazon's "restock now" alerts are based on trailing 30-day sales and don't account for seasonality, lead times, or your actual supply chain.

Fix: Build your own restock model using 90-day velocity, seasonal adjustments, and total lead time.

Mistake 2: Ordering Based on Supplier MOQs Instead of Demand Your supplier says the MOQ is 5,000 units. You're selling 50/day. That's 100 days of inventory.

Now you're paying storage fees for three months.

Fix: Negotiate lower MOQs, split orders across multiple shipments, or find a supplier with more flexible minimums.

Mistake 3: Ignoring Restock Limits Until It's Too Late You manufacture 10,000 units, ship them to FBA, and Amazon rejects 7,000 because you hit your restock limit.

Now you're paying your freight forwarder to warehouse rejected inventory.

Fix: Check restock limits BEFORE placing your manufacturing order. Plan shipments in waves if necessary.

Mistake 4: Sending Everything to FBA FBA is expensive. If you're sitting on 6 months of inventory, you're paying Amazon $2,000-$10,000/month in storage fees.

Fix: Use a 3PL for overflow inventory. Only send 60-90 days of stock to FBA at a time.

Mistake 5: Panic Ordering When You're Low You're down to 15 days of stock. You panic and air freight inventory from China for $8,000.

That $8,000 wipes out two months of profit.

Fix: Reorder when you hit 120 days of stock remaining (assuming 90-day lead time + 30-day buffer). This gives you time to use ocean freight.

Mistake 6: Not Planning for Promo Impact You run a Lightning Deal and sell 500 units in 24 hours. Now you're out of stock for two weeks while you wait for the next shipment.

Fix: Before running any promo, check: "If this promo performs well, will I have enough inventory to sustain the sales lift?"

How to Handle the Aged Inventory Fee Bomb

Aged inventory fees are Amazon's way of punishing you for slow-moving stock.

• 271-365 days: $6.90/cubic foot or $0.15/unit (whichever is greater)
• 365+ days: $6.90/cubic foot every month

If you have 2,000 units sitting in FBA for a year, Amazon charges you $300-$500/month until you remove it.

Here's how to avoid this:

Option 1: Run a Liquidation Promo Drop your price 40-50% and clear the inventory. Yes, you'll take a loss. But it's cheaper than paying Amazon $500/month in storage fees.

Option 2: Remove to Your 3PL Pull the inventory out of FBA and warehouse it yourself (or at a 3PL like ours). Cheaper storage, and you can use it for DTC orders or future restocks.

Option 3: Donate or Destroy If the inventory is truly worthless, donate it (tax write-off) or have Amazon destroy it (cheaper than ongoing storage fees).

At Marknology, we monitor aged inventory weekly. If something hits 240 days in FBA, we take action immediately (promo, removal, or liquidation).

When to Use a 3PL (And Why Marknology's Warehouse Matters)

Most Amazon sellers think FBA handles everything. It doesn't.

• Fast shipping (Prime eligibility)
• Customer service (Amazon handles returns)
• Simple logistics (you send inventory, Amazon ships it)

• Inventory flexibility (restock limits, storage fees)
• Multi-channel fulfillment (can't ship DTC or B2B from FBA easily)
• Cost efficiency (expensive storage, especially Q4)

That's where a 3PL like Marknology's Kansas City warehouse comes in.

Here's what we do for clients:

1. Receive and QC Inventory We receive shipments from your manufacturer, inspect for defects, and prep for FBA (labeling, poly-bagging, bundling).

2. Drip-Feed to FBA We hold your bulk inventory and send it to FBA in batches that fit within your restock limits.

3. Multi-Channel Fulfillment We ship DTC orders (from your Shopify store), B2B orders (wholesale), and TikTok Shop orders from the same inventory pool.

4. Overflow Storage We warehouse excess inventory at a lower cost than FBA, keeping your storage fees down.

5. Returns Processing We handle Amazon returns, inspect them, and re-prep them for FBA instead of letting them sit as "unsellable."

For clients doing $100K+/month, having a 3PL partner is the difference between profitable scale and operational chaos.

The Real Cost of Stockouts (And Why You Should Over-Prepare)

Here's the math most sellers miss:

• Lost sales: 14 days x 50 units/day x $30 profit/unit = $21,000
• BSR drop: 2-3 months to recover
• PPC waste: $5,000 in wasted ad spend (campaigns running with no inventory)
• Total cost: $26,000+

• Extra storage fees: 1,000 units x $0.50/month x 3 months = $1,500
• Total cost: $1,500

The cost of stockouts is 10-20x higher than the cost of over-ordering.

When in doubt, over-order. Storage fees are recoverable. Lost BSR isn't.

Final Take: Inventory Management Is the Hidden Profit Lever

Most Amazon sellers obsess over PPC optimization and listing tweaks.

Those matter. But inventory management is the hidden profit lever.

• Never stockout (consistent revenue)
• Minimize storage fees (better margins)
• Scale without cash flow crises (smarter capital allocation)

• Lose sales during peak season (revenue gaps)
• Pay thousands in unnecessary storage fees (margin erosion)
• Tie up all your cash in dead inventory (growth stalls)

At Marknology, we've built a system that works across 300+ brands. We use data-driven forecasting, strategic 3PL warehousing, and proactive SKU management to keep clients in stock and profitable.

If you're drowning in inventory chaos, we can help. No fluff, no long contracts. Just a conversation about whether our system makes sense for your brand.