I Use 50 Kg of Soy Wax Every Month and My Supplier Takes 10 Days to Deliver — At What Inventory Level Should I Reorder?

The working, line by line

The reorder level is the stock on your shelf at the moment you place the order. It is not the amount you order. In days, 25 kg is exactly 15 days of wax at 1.67 kg a day: 10 days of lead time and 5 days of buffer. If you pour 200 g container candles at an 8% load, each uses 184 g of wax, so 50 kg a month is about 272 candles, and 25 kg on the shelf is about 136 candles' worth.

The 10 days has to be the right 10 days. Lead time starts when stock touches 25 kg and ends when the new wax is weighed and on the bench. If the 10 days you have in mind is only the courier's part, add the time it takes you to notice, pay and unpack. If you check stock only on Mondays, add up to six days of noticing. Our pages do not quote delivery times, so this is your figure: take it from your last three orders and use the longest.

Choosing the buffer

Lead-time demand is arithmetic. Safety stock is a judgement about how often things go wrong and how much it matters when they do. There is no single right figure. Here are four ways to set it for this exact case, with the reorder level each one produces:

The max–min method needs two numbers from your own records: the highest daily usage in a recent busy week, and the longest lead time you have seen. The example uses 2.2 kg a day and 14 days, both illustrative. It sets safety stock so that your worst week and your slowest delivery arriving together still do not empty the shelf: 2.2 × 14 = 30.80 kg, minus the 16.67 kg of normal lead-time demand, is 14.13 kg. It is cautious by design, because it assumes both bad things happen at once.

For most makers at 50 kg a month, half the lead time is a sound place to start and is the answer used on this page. Move to the full lead time if deliveries vary by more than a few days or if a corporate order could land without warning. Once you have eight or more weeks of usage records, I Have Enough Raw Materials for 500 Candles but Sales Are Growing Unpredictably — How Much Safety Stock Should I Maintain? shows how to size the buffer from the actual spread in your sales rather than from a rule.

Stress-testing 25 kg

The table below places the order at 25 kg and then lets the delivery take longer, or the fortnight run busier, than planned. The last column says whether you still have wax when it lands.

At normal usage, 25 kg survives a delivery up to 15 days, 5 days late. It survives a busy fortnight on its own. It does not survive a busy fortnight and a 14-day delivery together: that combination needs 30.80 kg and runs 5.80 kg short, about 32 candles. If that pairing has happened to you before, either raise the reorder level to around 31 kg or treat busy periods as events and order ahead of them, which is cheaper than holding the extra wax all year.

How much to order at 25 kg

The reorder level says when. The order quantity says how much, and it decides how much cash sits on the shelf. With the order placed at 25 kg and landing on the 8.33 kg safety stock, your maximum stock is safety stock + order quantity and your average stock is roughly safety stock + half the order:

Fortnightly ordering keeps 12.5 kg less wax on the shelf on average, worth ₹7,487.50 on Chunks and ₹6,342.50 on CSI 464. The reorder level does not change: it is still 25 kg, because the lead time and usage are the same. Only the height of each tooth in the diagram changes. Against that, fortnightly means twice the orders, and any shipping charge or time you spend per order counts against it. Those are your figures to add. I'm Paying Shipping Separately Every Time I Reorder Small Quantities — How Do I Calculate Whether Larger Raw-Material Orders Would Actually be Cheaper? works through whether larger, fewer orders cost less once delivery charges are included.

50 kg in packs and rupees

CSI's listed soy wax packs stop at 10 kg, except Natural Soy Pearl, which is also listed in 50 kg. Here is one month of wax, and the 25 kg reorder level, in each:

Two things stand out. First, Luxury Soy Wax Chunks are fractionally cheaper in 5 kg packs than 10 kg: ₹2,995.00 for 5 kg is ₹599.00 a kilo, while ₹5,999.00 for 10 kg is ₹599.90. At 50 kg a month that is ₹45.00. Second, Natural Soy Pearl's 50 kg pack costs exactly the same per kilo as its 5 kg and 10 kg. Its real break is from 1 kg to 5 kg: buying 50 kg as 1 kg packs would cost ₹22,500.00, ₹1,260.00 more. At 50 kg a month you are already past that break with any pack from 5 kg up.

Changing wax changes the candle, not only the bill. Wick, fragrance load and cure behave differently in each, so treat a switch as a new formula: test burn it in your jar before the monthly order changes. For the cost side of that decision, My Premium Soy Wax Costs More per Kg but Produces Fewer Rejects — How Do I Calculate Whether It Is Actually Cheaper than My Budget Wax? compares a dearer wax with fewer rejects against a cheaper one.

Wax is not the only material with a reorder level. At 50 kg of wax a month you are pouring roughly 270 candles, which means roughly 270 wicks and 270 jars, and a stock-out of either stops production just as surely. I'm Constantly Placing Emergency Raw-Material Orders — How Do I Calculate Minimum Stock Levels for Wax, Fragrance, Wicks and Jars? sets minimum levels across all four materials so that they run out together or not at all. For fragrance, where each scent sells at its own speed, see My Candle Business Uses 20 Different Fragrance Oils — How Do I Set Separate Reorder Levels for Fast-Selling and Slow-Selling Scents?.

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