Peak inventory planning: how to plan when you can’t forecast it

You don’t need a perfect forecast to plan for peak. You need last year’s numbers, a sensible buffer and a packaging stock reservation you’ve made before everyone else does.

Good inventory planning at peak isn’t about predicting demand to the unit. It’s about making sure you can absorb a surge without running out of the products, or the packaging, that get orders out the door. This guide is for operations and e-commerce managers who own stock and fulfilment through the busiest weeks of the year.

In this article, we’ll cover:

Why you can’t forecast peak perfectly, and why that’s fine
How to build a peak plan from your own historic numbers
How much capacity buffer to add on top
The trigger point that tells you to act now
How to turn the plan into a packaging stock reservation

Why does inventory planning beat forecasting at peak?

Peak demand is volatile by nature, so no forecast will be exact, and you don’t need one to be. Promotions, weather, courier issues and a single viral product can all move volumes in ways no model catches in advance.

This is where inventory planning and demand planning part company. Demand planning tries to predict what will sell. Inventory planning makes sure you’re ready to fulfil whatever does. At peak, the second job matters more, because the cost of being caught short is far higher than the cost of a small buffer.

So, treat sales forecasting as a starting estimate, not a promise. Plan for a range, protect the downside and keep the flexibility to react. Think about product flexibility; packaging you can use across your whole range rather than specific solutions for specific products.

How do you build a peak plan from last year’s numbers?

Start with the data you already own. Your own history from last peak is a better guide than any generic benchmark, because it reflects your products, customers and courier mix.

Volumes, stockouts, delays and returns

Pull five things from last peak:

Daily order volumes
Anything that sold out
Deliveries that ran late
Returns that came back in January
Order profile: is each order bigger than the usual?

Stockouts and delays are the most useful, because they show exactly where last year’s plan broke.

Basic demand forecasting for e-commerce is often this simple: take last year’s peak shape, adjust for growth and you have a working baseline.

Adding a capacity buffer

Add a buffer on top of your baseline so a busier-than-expected week doesn’t stop despatch. The buffer covers the fast-moving lines, the packaging to ship them and the packer hours to get them out.

Keep it proportionate. A buffer that’s too large ties up cash and warehouse space, which is the opposite of what you want going into peak. Weight it towards your bestsellers, anything branded and the consumables you can’t or don’t want to pack without.

How do you turn the plan into a packaging stock reservation?

A stock plan that ignores packaging is only half a plan. Every order you forecast needs a box or bag, protection and a way to seal it, and peak season packaging demand rises across the market at the same time you need it.

Translate your forecast into consumables. Match your top-selling lines to the right cardboard boxes, work out the void fill and packing tape each parcel needs, then reserve enough to cover your buffered volume.

Getting the box right also protects the order. The wrong size or too little protection is a common cause of damage and returns, so it’s worth reading how to reduce damage in transit before you finalise the plan.

Check how order profiles have changes in previous peak periods. You may need more than the average number of larger boxes. Uplift volumes may not be consistent across your whole packaging range.

What to do next

You can plan a strong peak without a crystal ball. Build the baseline from your own history, add a proportionate buffer, set a trigger point and turn all of it into a packaging reservation you make early. Inventory planning is one part of getting ready for e-commerce peak season.

The one step most operations leave too late is the packaging. Reserve it while stock is plentiful and lead times manageable, so next-day availability is easy, not when the whole market is buying at once.

Talk to a packaging expert about your peak plan. Bring your forecast and we’ll help you turn it into the right stock of boxes, protection and tape. Talk to a packaging expert.

Key takeaways

Peak inventory planning is about being ready to fulfil a surge, not predicting demand to the unit.
Build your baseline from last year’s own volumes, stockouts, delays and returns, then adjust for growth.
Add a proportionate capacity buffer weighted towards bestsellers and the consumables you can’t pack without.
Set a trigger, such as orders running 20% above baseline for two weeks, so you act on data rather than gut feeling.
Reserve packaging stock early, because peak season packaging demand rises across the market at the same time.

FAQ: Peak inventory planning

Can I plan for peak without an accurate forecast?

Yes. Use last year’s peak as your baseline, adjust it for business growth, then add a capacity buffer. Being ready to absorb a surge matters more than forecasting it precisely.

What data should I use to plan peak stock?

Your own historic data is the strongest source: daily order volumes, stockouts, late deliveries and January returns from last peak. It reflects your real products, customers and courier mix.

How much buffer stock should I hold for peak?

Enough to cover a busier-than-expected week on your fast-moving lines, without tying up excess cash or warehouse space. Weight the buffer towards bestsellers and essential packaging consumables.

What’s the difference between inventory planning and demand planning?

Demand planning predicts what will sell. Inventory planning makes sure you can fulfil whatever does. At peak, being ready to fulfil matters more than the accuracy of the sales prediction.

When should I reserve my peak packaging stock?

As early as possible. Reserve it in late summer to early autumn, before market-wide demand climbs. Leaving it until November risks shortages and slower availability exactly when you need packaging most.

What happens if I run out of packaging during peak?

Despatch stops even when the products are in stock, because you can’t ship what you can’t pack. Reserving boxes, protection and tape ahead of peak removes that single point of failure.