The Million Dollar Case Study Session #22: Amazon Inventory Management

Predict the unpredictable. This is the impossible task that Amazon sellers, and frankly, retailers since the beginning of time, have had to do to maximize their potential profits. However, if you are an Amazon seller and find yourself with a dreaded Out Of Stock note on your product detail page, the consequences are costly and painful: a plummeting Best Seller Rank, evaporating organic sales, and most importantly, lost profits.

Track product ideas & Amazon review trends with Jungle Scout by using the Web App.

The solution to this challenge lies in inventory management. And there is no better person to learn the topic from than Jeremy Biron, Founder of, and an Amazon seller for the better part of a decade. In this session, Jeremy takes us deep into the topic of inventory management, to learn how to forecast demand, management inventory, and maintain a healthy cash flow.

Here is a full recap of the webinar:

And here are the slides for reference:

The crux of good inventory management is that it helps you manage cash flow effectively. With an Amazon business, a lot of capital can be tied up in the beginning, as you invest in purchasing inventory to sell. Proper inventory management allows you to find that balance of stocking the right amount of inventory without tying up an excessive amount of capital in inventory that sits in an Amazon warehouse. Ultimately, if you are able to pair a profitable product with good inventory management, then you can create a well-oiled cash machine primed for growth. Now that sounds quite appealing!

Jeremy lays out the formula for effective demand forecasting and inventory management by figuring out a few key figures.

Let’s go through this one at a time, using Jungle Snugs as an example, to figure out when these should be reordered, and how many should be ordered.

Question #1: What Is The Lead Time?

Lead time is simply the number of days required from placing an order with your supplier to having it ready for sale on Amazon.

There are a variety of steps that need to be considered (you can go through the overview page of the Million Dollar Case Study to see each of these in detail), but these considerations include manufacturing time, packaging, shipping time, customs and importing, domestic shipping to Amazon’s warehouses, etc.

When calculating your lead time, it is crucial to be honest with your assessment, as a miscalculation here can have ramifications in subsequent calculations.

For Jungle Snugs, the Lead Time is as follows:


There are some implicit considerations here, such as: How reliable is the manufacturer? Is there likely to be a delay in manufacturing, packaging, getting it to port, etc? Is it likely that there is a delay with customs or paperwork about importing the product? All of these can impact what the lead time is.


Question #2: What Is Your Safety Stock?

Safety Stock, or “Buffer”, is your insurance inventory against a stock out. Basically, it is the extra inventory that you are willing to hold to avoid missing out on lost sales in the case of a surge in demand.

When calculating your safety stock, you need to ask yourself whether you are willing to invest more cash in inventory to avoid missing out on future sales. Again, assessing this Safety Stock figure is a ultimately just a best-guess, as you are predicting the unpredictable.

One suggestion that Jeremy offers is to not overinvest in safety stock, as tying up too much capital in idle inventory can undermine sales that you could have made elsewhere by selling a different product.

You can calculate your Safety Stock by using either days, or a percentage of your total inventory. For Jungle Snugs, we used 25% as Safety Stock.

There are two factors complicating this estimate for Jungle Snugs:

  1. Jungle Snugs has a long lead time, as the product ships by sea so it is harder to get a quick turnaround and restock inventory. That is one consideration when having a higher Safety Stock.
  2. As it is a relatively new product, there is limited sales history, so it is hard to predict how sales will proceed. Thus erring on the side of caution, the Jungle Snugs will have a roughly 25% Safety Stock.


Question #3: What Is Your Sales Velocity?

Sales velocity is simply how fast you sell your inventory. How many units per day/week/month/year etc do you sell?

This is the sales velocity calculation for Jungle Snugs:

Question #4: What Is Your Current Inventory?

Take a look in Seller Central to see how much inventory you have left. Jungle Snugs currently has 537 units in stock.

Question #5: What Is Your Reorder Point (in number of units)?

Your reorder point is basically assessing when you should reorder, based on how many units of inventory you have in stock.

Here’s the calculation for the reorder point:

The calculation above takes into account how long it takes to get inventory (aka your Lead Time), and how fast you are selling units (aka your Sales Velocity).

So when should we have reordered Jungle Snugs? Jeremy advises that when you place your order is actually more important than how much you order when managing your inventory.

We have 537 units in stock, plus we would want an additional 159 units (the safety stock). We are selling almost 10 per day (our 9.8 sales velocity). At this rate, we should have ordered 26 days ago, knowing that we calculated 65 days to have inventory ready for sale.

Alright then, time to order more units, STAT!

Question #5: How much should we order?

This seems like the kicker—the most important question to answer. How many units do you order?

Basically just figure out how many days of inventory you have in stock, and how long it takes you to get inventory after you place an order and convert that into actual units of inventory. This is the quantity calculation for Jungle Snugs:

Including the safety stock, we will need to order 1688 units. But don’t forget to round to the even case quantities, which will differ depending on your particular product.

Additional Tips For Savvy Inventory Management

Here are some other things to think about to be more prudent with inventory management:

  • Return on Investment – how many units are you investing in, and how much will you make on that in return? What is the Return On Investment on your product? Jeremy reminds us to not think about profit in absolute terms, but as a percentage of your investment. It would be awesome to make $1000, but did you have to invest $20,000 to make that, or $1,000. Clearly, you want to maximize your return on investment as much as possible!
  • Import Via Ocean or Air – Importing by sea or air is a constant question for sellers. Do you wish to get the speed and flexibility of air or the cost-savings of ocean freight? It depends on your needs at a given time, as each has its pros and cons.
  • Product Segmentation – once you’ve been selling a lot, it’s important to have safety stock for your best selling products. Use a higher multiplier for your Safety Stock to ensure that you always have your best selling products on hand. Definitely focus on your best sellers with inventory management.
  • Plan Ahead – Think about your next order, not just today’s order. Pick suppliers that are good communicators, so you can be able to understand what your lead time will be, as it can be often changing.
  • Know Your Assumptions – Your calculations for inventory management rely on solid assumptions. Your lead time, sales velocity, safety stock, etc. All of this can affect your decision on how much inventory to keep, and therefore what your cash flow, growth rate, and profits can look like.


A Final Gift

Jeremy put together some spreadsheets to help make the inventory management calculations easier. These spreadsheets can help you figure out each of the calculations we examined above.

You can download the sheets AT THIS LINK.

Thanks to Jeremy for an actionable and important session on inventory management. Understanding these concepts can have significant impacts on how our Amazon product fares, as inventory management is a key lever in maximizing cash flow and profits.


Next Up

Have you heard the news yet? We are moving over to part 2 of the Million Dollar Case Study… and we’re going to Europe.

Join us, we’re going to cover the full and unfiltered process for finding and launching a profitable product in Europe, and all of the business tasks that go with selling in a brand new marketplace. You’re not going to want to miss this one.


25 comments on “The Million Dollar Case Study Session #22: Amazon Inventory Management

  1. Hello, thanks for your blog. I have a question.
    About day of inventory = 13 weeks (91 days). I don’t know how to calculate this days? Is it 2 x 65 days + 26 days stock out? Why double 65 days after that add more lead time? Could you explain it please

    Thank you

  2. i don’t think that this product is gonna generate a million dollars as appose to jungle stix, see jungle stix is a consumable product you can’t reuse it, it’s gonna sell to the same people more than once simply because theyre out of stock, but when you put jungle snugs into prespective it’s a reusable product people buy it once and often remain for generations.
    my point is jungle stix is a more apealing product to market it’s just common sense

    1. Good insight, Ibrahim!

      Consumable products are some of the best products to use. Tim Ferriss even suggested those in his book (although, he warned away from edible stuff).

      Sometimes, products develop synergy by attracting different, but related markets. So while the snugs themselves may take a while to get some momentum, they’ll help lead to the stix and vice versa.

      I guess we’ll have to see what happens!

  3. Yo Kym,

    Since you’re still here checking in on these comments: any idea what happened to the 3rd spreadsheet tool that Forecastly’s founder wanted Greg to send out? It’s not posted here on the blog or youtube description (as promised). The other two were easy to find but there is one that’s missing (according to the webinar). Would love to get that apparently killer sheet so I can realize how bad sheets suck and upgrade to Forecastly.

    Fingers crossed you see this post.


    1. Hey Mike,

      I investigated this and you are right there was one resource missing. If you head back to Forecastly now and request the resources again you should be able to access all three.

      Thanks for reading 🙂

  4. Thank you, Kym.

    Just one last question since your here. In your experience, generally speaking, when does the lead time clock start ticking?

    Is it when the 30% deposit is paid and being processed or when the payment is finally cleared? I didn’t want to ask the supplier and come across as a rank amateur and couldn’t really find this specific bit of information with a google search.

    1. Hey Mo,

      No problem at all, happy to help 🙂

      In my experience of ordering my first inventory, the clock started ticking once the deposit was paid… I used Alibaba Trade Assurance, but you still process this similar to a T/T and you should get a payment confirmation. My supplier was happy to take the payment confirmation as a ticket to purchase the raw materials and get started.

      I’d recommend aiming to do the same, and if the supplier won’t agree to this, then you may have to wait until the payment clears (at least until you have formed a relationship and they know that you always pay on time).

      Hope this helps,

      Many Thanks,

  5. Hi,

    I have a question regarding lead times and calculating reorder points. When you state lead times of 30 days, these are not really accurate. I’ve found during supplier research that lead times are only working days, Mon-Fri and don’t include weekends.

    So, in reality, a lead time of say, 30 days, is really 40 days as you have to factor in 10 weekend days as factories don’t work on weekends. Are you factoring this in? As this has a major impact on the ‘reorder point’ and ‘days until order’ when using the free Forecastly template.

    I’ve never heard anyone mention this to new sellers. When I first started earlier this year I made this mistake and went back noticed this wasn’t mentioned/ made clear in the jungle stix or million dollar case study.

    1. Hi Mo,

      Good point, I think it varies depending on your factory, what hours they work, and whether or not they give you an accurate lead time, or a lead time taking weekends into account.

      In addition to that, you may also have to alter your lead time using this template due to other factors, such as public holidays in China, which can increase your lead time.

      It’s just a guide for sellers to adapt to their own specific needs. However you make a very good point that sellers should be sure to check whether the lead time stated includes weekends or not.

      Thanks for joining and writing in 🙂


  6. I have either missed it or it’s been mentioned in another webinar (even though I watched them all). The lead time you’re mentioning here does it take into consideration the fact that Amazon once it receives your product it takes its time to make it available for sale. Can someone shed some light here? Shouldn’t that add to the 65 days? As I have carefully watched you are mentioning up until it gets to Amazon’s door. But the product won’t be really available until Amazon processes it right? And that could be up to 14 days as a very polite guy in India (seller support!) has told me.

    1. Hi Christos,

      You are right about this and as far as I know, it’s not really something you can determine. It depends on how busy the Amazon DC is, and of course during 4Q this can be very busy and you may well end up waiting longer for your inventory to be processed and listed as in stock.

      I would imagine the response from seller support was a worst case scenario, so when managing your inventory, you can try to account for this, especially around busy periods like holidays or the lead up to Prime Day. But in my experience it usually happens within 24 hours, or a few days at the most.

      It’s all about forward-planning 🙂

      Many thanks,

  7. I sent a E-Mail that maybe you guys would get it. It is about expanding your baby hooded towel to different regions. Google Trends is showing Interest and searches for these hooded towels in the UK and Australia. In fact there is more interest and searches than in the US for this item. UK is ranked 100 vs the US at 50. US comes in 3rd behind UK and Australia in google trends.
    Just thought you guys might look at this as well.

  8. Gen –

    I have watched the studies and your helpful youtube videos…but want to ask you a question. I have been noticing every time I add a private label product, many others do also. When that happens competition increases, prices go down and PPC is very expensive cost/click.

    Currently, I have a newer private label that now price has gone down and PPC is $3-4 per click to even get your ad on first page. My marketing costs are in the thousands and that is hard to maintain as I have been doing this for less than a year and don’t have extremely high profits on other products. How would you handle this? Keep marketing until I get a organic spot? or grow slower…

    1. Hi Tara,
      Glad that you’ve found everything helpful. Yes, the conundrum of increasing competition….as you can see what we did with jungle stix and jungle snugs, we focused on the product launch phase, to get as many reviews and sales as possible. Focusing on getting discounted sales could help your organic ranking in a more cost effective way (they still count towards your sales velocity). alternatively, since it sounds like you’ve been running a fair amount of ads, scour through your search term report, and see if you can identify any obscure words that your competitors haven’t picked up on and have lower CPCs. this could be a way to get profitable conversions with paid spend. hope this helps!


  9. Hi Gen/ Greg,
    Hows the customs charge normally if the items arrived by sea freight?
    Please advise if possible.
    Thanks and regards

  10. Hi Greg – Saw your P&L for Jungle Snugs in Webinar 16. Your sea shipping cost is around USD 700. My first product is in the same range by weight and dimensions but the shipping cost I incurred was USD 2900 (I used a prep and ship because I dont live in the US). This coupled by a high FBA fee is killing my P&L. Any suggessions on how I can get better shipping rates. I tried Freightos but the quotes I was getting there were also in the same 2500-3500 range.

    1. Hi Jameel,

      The best thing is to shop around at a variety of options, and ask around for who has the best rates in various seller communities. And obviously, if you send higher volumes of stuff, your rates go down. In the beginning, our profits were diminished a bit by the higher shipping costs, but improved over time!

      hope this helps.


  11. Hey Gen / Kym / Greg,

    Obviously we don’t want stock-outs, but in the event we have them, I’m assuming that will hurt the BSR because of the zero sales velocity. My question is, how quickly does that build back up once you’re back in stock? Would I need to do simulate another product launch to build up the sales velocity again?



    1. Hey Jason,

      For sure, a stock out can take it’s toll on your listing and your rankings.

      It can take some time to build back up too. I would definitely recommend doing another “launch” to get back up there. A combination of a promotion (to boost sales velocity), and some smart Amazon PPC campaigns will really help speed things up.

      Many thanks,

  12. HI

    1. Hey Ashley, if the product is already on the way to Amazon, and unless your supplier can help and send a single sample to your photographer, it may be easiest to wait until your inventory arrives at the FBA warehouse.

      Then you can order a product on Amazon direct to your photographer.

      Many thanks,

  13. Wait, just to clarify, I thought the MDCS was getting to 1 million dollars with one product – it sounds like you are combining Jungle Stix and the new product you will launch in Europe together with Jungle Snugs in order to reach that goal. Am I correct?

    I appreciate the aspect of reality that it adds to the case study. In other words, I wouldn’t expect a “normal” business to focus only on one product only on one market place, so it makes sense to expand both in products and in marketplaces. However, it takes away from the allure of the MDCS.

    In regards to this webinar, are you shipping your next order by sea? Will you know make a rush shipment on a smaller quantity by air to avoid the stock out days?

    Thanks again,


    1. Hey Steve,

      When we set out on this case study we mentioned this – the aim is for us to build an Amazon business and generate $1 million in sales, and to do that we will explore any avenues that would help us to scale.

      At the beginning we mentioned that this might mean launching new products or exploring new marketplaces. In a nutshell, we’re going to do what ever it takes to grow fast, share our processes and raise money for charity. Not only that, it helps us to show the viewers how to build a real-world, scalable and successful business on Amazon 🙂

      Since launching the case study it became obvious that launching in Europe would be a great way to scale and an insightful thing to share with the community.

      I think Greg has ordered the next order by sea, but I will check with him on that one! If you know you are going to have some stock out days, ordering a small amount by air is definitely one way to prevent the negative effects on your listing!

      Thanks for reading!

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