Forecasting

The last order of the season, and how much to buy

Most seasonal advice stops at aim for zero. The sum that gets you there is short, and it only works because you know the date.

Marcus VolstedCo-founder, Restocio Published 10 October 202612 min read

The last order of the season is the units you will still sell before the season ends, minus what is on the shelf, minus what is already on the way, bought on a route that lands with enough selling days left to clear it. That arithmetic only works because the end date is known. Swimwear that stops selling in September, or a winter coat, has a calendar boundary you can write down today. A product that is simply selling less each month, with no date attached, is a different problem, and this page does not try to solve it.

Most seasonal inventory advice gets as far as "aim to end the season at zero" and stops. That is the right goal and a useless instruction, because it names the destination without the sum that gets you there. The sum is short and needs only numbers you already have. The one thing that makes it possible is the date.

A known end date is a different problem from a decline

Two situations look alike from the outside and need opposite handling. One is a product losing pace with no end in sight, because a competitor turned up or a trend went cold. The other is a product that sells well right up to a date and then stops because the calendar says so. The first is a question about whether the fall is real, and an honest answer takes weeks of evidence. The second is not a question at all. You know the date. The whole job is converting it into a quantity.

	A product that is fading	A product with a season end
What you know	The rate is falling. You do not know when it stops	The date it stops. The rate holds until then, more or less
What a trailing sales rate does	Lags the fall and keeps buying at the old pace	Stays roughly right, then becomes irrelevant overnight
The question to answer	Is this noise or a real decline	How many selling days are left after the goods land
The lever	Shorter cycles, re-measure sooner	Subtraction: days left times the rate, minus the shelf, minus what is on the way
When to stop ordering	When the evidence says so, which takes time	A date you can compute this morning
What goes wrong	A little too much, every cycle	One order too many, carried into next year

The other two ends of a product's life are covered elsewhere on this site. A product with only weeks of history is the beginning. Dead stock is what you hold when a last order goes wrong. This page is the specific moment between them: the final purchase before a date you can see.

Why aim for zero is the goal, not the instruction

Ending at zero is correct for most seasonal goods, and the reason is cash rather than tidiness. A swimsuit bought in June and unsold in September is money sitting in a box until next May, or longer if the colour dates. Ending slightly short, a handful of lost sales in the final week, is cheaper than carrying a quarter of a container through the off-season. The two mistakes are not symmetrical, and that asymmetry runs through everything below. When you have to guess on a final order, guess short, which is the reverse of the rule for a product that sells all year.

One qualification. If the product comes back unchanged next year and the cash is not needed elsewhere, the asymmetry shrinks, and the formula can carry a little more. A classic black swimsuit is not an advent calendar.

The arithmetic of the last order

Five numbers, and you already have every one of them. The sales rate, measured over the days the product was actually in stock. The selling days between today and the end of the season. What is on the shelf. What is already ordered and landing before the end. The route's lead time, door to door, with production included.

last order = rate × selling days left in the season − stock on hand − anything already landing before the end

Then two checks on the route. It has to land with selling days to spare, so days left minus lead time has to be worth an order. And if the shelf runs out before the goods land, those empty days are not added back. They are sales that did not happen, and the order shrinks to the rate times the days after landing.

Notice what the lead time does here, because it is the opposite of a normal reorder. On a year-round product, lead time makes the order bigger: the shelf has to survive the wait. On the last order of a season, as long as the shelf lasts until the goods land, the lead time cancels out entirely. The days the goods spend travelling are sold from stock you already own, so the order is simply the days left times the rate, minus what you hold. Lead time only bites in two places: it decides whether a route can land at all with time to sell, and if the shelf empties first, every empty day comes off the order rather than onto it.

A worked example, swimwear with 92 selling days left

A swimwear line sells from May to August. It is 1 June, so 92 selling days remain, counting both ends. The product sells 10 a day measured over in-stock days, 450 units are on the shelf, nothing is on order. The lead times, door to door, are the ones our own worked examples run on: 70 days by sea, 20 by rail, 5 by air.

Units still to sell before 31 August: 92 × 10 = 920. On the shelf: 450. The season needs 470 more units from somewhere, and the only open question is which route can deliver them with time to sell.

Route	Lands on	Selling days after landing	Shelf when it lands	Last order that clears by 31 August
Sea, 70 days	10 August	22	Empty since 16 July	220, and 25 days of sales are lost before it lands
Rail, 20 days	21 June	72	250	470
Air, 5 days	6 June	87	400	470

Rail and air give the same 470 because the shelf outlasts both journeys, so the lead time cancels. Sea is the odd one out. The boat docks with 22 selling days left, so the most it can usefully carry is 220, and the 25 days between the shelf emptying in mid-July and the boat arriving are gone whatever you order. If your sea rate is well under your rail rate, the cheapest plan that still clears is the usual split, 250 by rail landing in June and 220 by sea landing in August, which is the bridge arithmetic applied to a season instead of a cycle. Whether the rail premium on 250 units beats 250 lost sales is a margin question, and the answer is usually yes.

Now move the calendar and watch the number shrink on its own. Run the same product with 450 on the shelf on 1 July instead: 62 selling days remain, so 620 minus 450 is 170, on rail or air, because the boat would land in September. On 1 August it is 310 minus 450, below zero. Order nothing, and the shelf finishes the season with about 140 units over. That self-shrinking is the one property a year-round formula lacks, and it is the entire reason a known end date changes the sum.

When to stop reordering, per route

The second question, when to stop, is the same arithmetic read from the other end. A route stops being usable on the day it can no longer land with the selling days you insist on having after it docks. Two weeks is a sensible floor for most products: below that, the final order is a pack or two, and one late shipment turns the whole thing into next year's stock. Pick your own floor, but pick it in advance.

last day to order by a route = season end − that route's lead time − the selling days you want after the landing day

Route	Lead time	Lands by 31 August if ordered by	Last order day, keeping 14 days after it lands
Sea	70 days	22 June	8 June
Rail	20 days	11 August	28 July
Air	5 days	26 August	12 August

Put those dates in the calendar in spring, because none of them will announce themselves. The 8 June boat deadline falls while the shelf is full and the product is selling at its best, which is exactly when a stock level says nothing and a date says everything. After 12 August there is no route left, and whatever the sales rate says that week, the correct order is zero.

The pace near the end is not the pace in the middle

One input deserves a second look. The rate in the formula is measured backwards, over the last 60 in-stock days or so, and on a product that peaks in July that window still carries July well into August. Many seasons tail off before the calendar says they are over. For the final order, look at the most recent two or three weeks beside the 60-day figure, and if they are lower, use the lower one. The cheaper mistake on a last order is ordering short.

What Restocio does with a seasonal product, and the part it does not do

You set the months per product in SKU Manager, under Costs & weight, where each row's menu has "Set a season". The row then shows the months, May to August say, and three things follow from them.

Before the season, from 30 days before its first month, the product is sized on what it sold in the same months last year rather than on its trailing rate, which in April is the off-season and would be near zero. With no last year to read, the trailing rate is used instead.
In season, the ordinary rate applies: units sold over the days the product was in stock, over a 60-day window.
After the season, from the first day after its last month, the product leaves the replenishment list. It is counted under "out of season" with its months and the units still in stock, so the leftover is visible without being reordered.

Here is the honest part. Inside the season, the order is sized exactly as any other product's: on what the shelf will hold when the boat lands, enough to cover the voyage plus the cushion, with a fast bridge added if the shelf empties before then and what is already on the way subtracted. Nothing in that chain reads the season's end date. On 1 June in the example above, with 45 days of stock, Restocio proposes 1,000 units by sea and 320 by rail, 1,320 in total, on the settings our own worked examples run on (a 70-day boat with a 30-day cushion, a 20-day train with 7, a 30-day cycle). The live default cushion is 60 days, which makes the boat order larger still. The season-bounded answer was 470. On 31 August, the last day of the season, the app would still propose a full order, and on 1 September the row would move to the hidden list with the result sitting in it.

So for the last order of a season, work the number out with the formula above and type it on the freight line. A quantity you type replaces the app's figure for that line, and the rest of the plan, the other products and the purchase order, carries on as normal. The loop that follows is in the Shopify replenishment guide. Shrinking the final order to the days left is a calculation we understand and have not built, and we would rather say that plainly than let a confident number buy you a September full of swimwear.

What to do with what is left

If the last order lands and the season still ends with units over, that is not a forecasting failure to agonise over. It is stock at full value with eleven months of cover, and the first band in the dead stock guide applies: do nothing expensive, and do not reorder. The decision that mattered was the one above, made in June.

Common questions

How much should I order on the last order of the season?

Multiply your daily sales rate by the selling days left until the season ends, subtract what is on the shelf and anything already landing before the end, and buy the result on a route that lands with selling days to spare. If the shelf will run out before the goods land, the empty days are not added back. The order shrinks to the days after landing, and those lost sales are the cost of ordering late.

When should I stop reordering a seasonal product?

Work backwards from the end date, per route. Take the season's last selling day, subtract the route's lead time door to door, then subtract the selling days you want after the landing day, with two weeks as a reasonable floor. On a season ending 31 August that is 8 June for a 70-day boat, 28 July for a 20-day train and 12 August for a 5-day flight. After the last of those dates the correct order is zero, whatever the sales rate says.

What if the supplier's minimum is bigger than the last order?

Then the surplus is next year's stock on the day you sign, and it should be judged that way. Compare the minimum against the season-bounded number, not against an ordinary reorder quantity. If the product comes back unchanged next year and the cash is not needed elsewhere, carrying the surplus can be fine. If the style dates or cash is tight, negotiate the minimum down or let the last fortnight run short.

Should I size the last order on the 60-day sales rate?

Use it as the starting point and check it against the last two or three weeks. Late in a season a 60-day window still carries the peak, and many seasons tail off before the calendar ends. If the recent weeks are lower, use the lower figure. On a final order the cheaper mistake is ordering slightly short.

Does Restocio know when my season ends?

It knows the months. The day after the season's last month, the product leaves the replenishment list and is counted as out of season with its remaining stock. What it does not do is shrink the last in-season order to the days left. Inside the season a seasonal product is sized like any other, so for the final order of a season work the number out by hand and type it on the freight line.

When does Restocio start sizing a seasonal product before its season?

Thirty days before the first month of its season. From that day the product is sized on what it sold in the same months last year, so a product with no sales in the trailing window still gets a pre-season order. Thirty days is shorter than a boat, so a sea order for a season has to be placed while the product is still listed as out of season.

Marcus Volsted

Co-founder, Restocio

Marcus co-founded Restocio and works on it daily with a Swedish importer who plans their purchasing in it every working day. Restocio is built in Sweden by two founders, one Swedish and one Danish, and Marcus is the Danish one. Why we are building it.