My Monthly Wax Consumption Varies from 30 Kg to 80 Kg — How Much Safety Stock Should I Maintain Without Overbuying?

Forecast the predictable swing; hold safety stock only for the surprise — about 5.4 kg here

Most makers whose use swings between 30 and 80 kg a month try to cover the whole swing with safety stock. They keep 80 kg — the worst month — on hand all year. That never runs out, but it means holding about 56.6 kg of wax on average, worth ₹33,893.42 at the Luxury Soy Wax Chunks rate, most of it sitting idle through May and June. That is the overbuying the title wants to avoid.

The fix is to split the swing in two. Part of it is predictable: in the example history below, October to December average 70.0 kg a month and the other nine months 39.1 kg. You know that is coming, so it belongs in your forecast and your order sizes, not in a permanent buffer. The rest is unpredictable: the month that comes in 8 kg above plan because a corporate order landed. Only that part needs safety stock, and it is much smaller. At a 95% service level and an example one-week lead time, one buffer for the whole year works out at 12.6 kg; split by season it is 5.4 kg for the nine ordinary months and 8.8 kg in the festive quarter.

The formula is the standard one: safety stock = z × σ_daily × √(lead time in days), where z is the service-level factor (1.645 for 95%) and σ_daily is the standard deviation of monthly use divided by √30. It assumes day-to-day variation is independent — an approximation you should state on your sheet, not a law. As a cross-check, the simpler "max-rate" method — (highest month − average month) ÷ 30 × lead time — gives 2.8 kg for the ordinary months. The two agree closely, which is a good sign the number is sensible.

Start from twelve months of real consumption

You need your own monthly wax use — from purchase records minus stock change, or from batch sheets. The table below is an example history that sits inside the reader's 30–80 kg range; replace it with yours. Twelve months is the minimum that shows a festive season once; two years is better.

Look at what the split does to σ. Across the year, use varies by 15.9 kg a month — but most of that is the festive jump. Within the ordinary months it is only 6.8 kg. Within the festive quarter it is 11.1 kg, though three months is too few for a confident estimate; treat that figure as provisional and update it after this Diwali. The Diwali 300 kg plan treats the festive peak as a dated production schedule rather than a statistic, which is the better tool when the spike is large and known.

Choose a service level, then read the buffer off the table

A service level is the share of order cycles in which you do not run out. 95% means that, on average, one reorder cycle in twenty dips into a shortfall. Higher is safer and more expensive, and the cost rises steeply near the top. The table gives the buffer at four common levels, for one buffer all year and for the seasonal split, valued at the Chunks 5 kg rate of ₹599.00 a kilo.

For most small candle businesses, 95% is a reasonable default: a stock-out costs orders and customer goodwill, but the extra wax for 99% — 2.2 kg more in the ordinary months — buys protection against rare months that a phone call to your supplier could usually cover. If a single stock-out would cost you a wholesale account, choose 98% or 99% and accept the extra stock as the price of that account.

Three policies compared: how much wax each one keeps idle

Here is what each approach means for the average amount of wax on your shelf. Average stock is roughly safety stock plus half of each order (cycle stock), because each order is used down from full to empty. Orders here are half a month's average use, rounded up to whole 10 kg: 30 kg on a single policy, 20 kg in ordinary months and 40 kg in the festive quarter. Policy A tops up to 80 kg at the start of each month.

Policy C keeps about 37.8 kg less wax on the shelf than keeping the worst month on hand — ₹22,643.92 that can buy fragrance, jars or festive stock instead. And it protects you to a stated 95%, which Policy A does not: A is safe in a normal year only because it holds a whole worst month, and it still runs out if a month beats 80 kg. Policy C also needs a monthly stock count to work — when wax becomes managed inventory sets up the stock card — and it makes a large bulk order harder to justify, as the 100 kg MOQ threshold shows.

Switch from the ordinary to the festive settings at the start of October — today — and back at the start of January. Each switch changes the number on your REORDER shelf label. The reorder-point post explains the reorder-bin method, and the procurement-system capstone turns both settings into one sheet.

Safety stock gets old: the aged-bag check

Safety stock is the wax you hope never to use. That is exactly why it ages: if you always pour from the newest delivery, the buffer bags sit for months. Rotate them — first in, first out — and once a season, check that an aged bag still pours like a fresh one. CSI's product page states a 60-month shelf life in cool, dry storage for Luxury Soy Wax CSI 464 (and for CSI 468); no shelf life is published for Luxury Soy Wax Chunks, Natural Soy Pearl or the other soy waxes, so for those the check is your only evidence.

The check uses the control method from the rest of this series. The control is a candle poured from a freshly opened bag; the test candle is poured from your oldest buffer bag. Same oil lot, same wick, same jar, same day. Three of each — two burned, one shelved — is a labelled working practice for a routine check, smaller than a full qualification because the wax itself has not changed. Label each bag with its delivery date as your own lot label; CSI publishes no lot numbers. Keeping a retained sample from every delivery and storing 100 kg through an Indian summer cover the storage side.

The check costs ₹1,148.42 a season against a buffer worth ₹3,249.37 in Chunks — or ₹2,752.47 in CSI 464 at its flat ₹507.40 a kilo. If your buffer turns over every few weeks because you rotate it properly, the check becomes a formality; if it never turns over, the check is the only thing standing between a forgotten bag and a festive batch. For per-candle context, a 200 g Citrus Lemon candle costs ₹232.23 in Chunks (5 kg rate) and ₹215.37 in CSI 464 (10 kg rate), wick and jar included, excluding labour, packaging, freight and GST.

The decision rule: how much safety stock, and when to change it

For this maker on 1 October, that means: raise the reorder point to the festive setting of 25.2 kg, order in 40 kg lots (80 × 500 g of Luxury Soy Wax Chunks, ₹23,920.00), and hold a buffer of 8.8 kg — 20 × 500 g (₹5,980.00). On 1 January, drop back to 14.6 kg with 20 kg orders and a 20 × 500 g buffer. Total wax on the shelf over the year averages about 18.8 kg, against 56.6 kg if you kept 80 kg on hand.

Related inventory questions

This page sizes safety stock for volatile use. Reorder points for a fast-growing business handles a steady upward trend; the Diwali 300 kg plan schedules a known festive spike by date; scaling from 25 kg to 500 kg a month covers the documents and supplier controls that matter as volume grows; and the procurement system puts it together. For a fixed one-week lead time at a steady 50 kg, see 50 kg a month with a one-week supplier.

Frequently asked questions