Plan sizes together with a size group

Enhanced plan

This guide plans a new product that comes in sizes, such as a T-shirt in S, M, L and XL, as one size group in a launch plan: set it up, take the size split from your sales history, adjust it, and order. Every control is explained on the Size groups page.

What a size group is and why you use one

A size group plans the sizes of one product together. Logistified forecasts the product as a whole, from one set of similar products with one Volume × and one launch date, and then splits that forecast across the sizes by a percentage per size: the size split. The split always adds up to 100%, so the sizes always add up to the product’s forecast.

Why not plan each size on its own? A new product’s total is much easier to estimate than each size separately, and the share each size takes is usually steady: M sells most, XS and XXL least. With a size group you plan the total once, take the split from what similar products sold size by size, and change one number when your expectations change. The order is rounded for the whole group, so small sizes don’t each get rounded up.

Plan variants as individual products instead when they don’t sell in a steady proportion, for example colours you expect to sell very differently.

Before you start

Your shop is on the Enhanced or Elevate plan.
The new product and its sizes exist in Shopify.
You know one or more similar products that come in the same sizes, ideally with a year of sales. Their size-by-size sales are what the split is suggested from.
You know how to create a launch plan. If not, start with Plan a product launch.

Steps

Set up the group

Go to Inventory Planning › New Product Planning, click Create New Product Plan, and fill in Plan Details and Launch & Horizon.
In Size groups, click Add group.
On the group card, click Add variants › Browse products and tick the product’s sizes. The group takes the product’s name, and the split starts even: four sizes get 25% each.
Under Similar products for the whole group, add the similar products. Every size uses them.
Click Suggest from history. The Suggest size split from history dialog shows each size’s suggested share, the sales behind it, and how confident the suggestion is, for example “Based on 840 sales, high confidence.”
If a size of the new product is named differently from the similar products’ sizes, change what it’s Based on. Then click Apply split. With little history, or a size that would get 0%, the dialog warns you first and the button reads Apply anyway.
Check that the total reads Total 100% and click Create plan. The plan opens with the size group as one row in the Week grid, its sizes beneath it.

Adjust the group on the plan

On the Week grid, pick a single location in the switcher (on a plan with several locations), then click the group row’s expander. The group panel opens.
Change what you need: the similar products, Volume ×, the Launch date, or the shares in the Size split table. Normalize brings a split back to 100% and keeps its proportions.
Click Save & rebuild. The group’s forecast is rebuilt and split across the sizes again. If you also moved the group’s Launch date, click Save above the table as well: the date is saved with that button, not with Save & rebuild.
If you edited some sizes’ weeks by hand, Logistified asks Keep your week edits? Choose Keep my edits, or Replace with the rebuilt curve to start those sizes over from their share.

On a plan with several locations, each location has its own copy of the group. Use Apply split to all locations in the Size split title row to give every location the same split, after Save & rebuild: until then it’s greyed out with “Save or discard your changes first”.

After launch: follow the real size mix

Once the product has sold for two weeks and at least 30 units at a location, open the group panel there. After launch shows each size’s Pre-launch share next to what it is Selling.
Check the warnings. A size marked as sold out may have sold more if it had been in stock, so its real share is probably higher than shown.
Click Use actual mix for the remaining weeks, check the shares and units in the dialog, and confirm. Only the weeks from today change; earlier weeks stay as planned. Tick Also at the other locations to give every location its own actual mix.
Changed your mind? Click Undo in the message, or Back to the pre-launch mix later.

Order the sizes

Open Actions › Create purchase order and set the Coverage window (days). After launch, keep Cover from on Today for a reorder.
Tick At least 1 per size if every size should be in stock at launch, even the ones the split gives very little.
Click Create draft PO (with one PO per location at several locations, for example Create 2 draft POs). The group is rounded once: five sizes needing 2.2 units each order 11 together, not 15.

See Ordering for a launch for the whole dialog.

Worked example

You’re launching a linen shirt in S, M, L and XL, modelled on two cotton shirts that sold 1,200 units in the same sizes last year. You create a size group with the four sizes, add both cotton shirts as similar products, and click Suggest from history: S 18%, M 38%, L 30%, XL 14%, high confidence.

You expect linen to run slightly larger, so after creating the plan you open the group panel, set L to 32% and XL to 12%, and click Save & rebuild. The group plans 600 units in its first two months; M plans 228 of them.

You order 60 days with At least 1 per size ticked. The group’s total is rounded once and shared out across the four sizes by the split.

Three weeks after launch the group panel shows M selling 46% against the 38% you planned, and XL at 9%. You click Use actual mix for the remaining weeks. From that day on M plans 46% of the group; the first three weeks stay as planned. Your reorder with Cover from set to Today follows the new split.

Common failure modes

Symptom	Likely cause	Fix
Suggest from history is greyed out	The group has no similar products yet.	Add similar products to the group first.
”None of the similar products have sales in these sizes yet, so the split is even.”	No similar product sold in these sizes.	Change what each size is Based on, or pick similar products with the same sizes.
A size gets 0%	No similar product has a matching size, so its Based on reads Not set.	Pick a size for it under Based on, or type its share yourself.
Save & rebuild is greyed out	”Save or discard your week edits first”: a size has week edits that aren’t saved yet.	Click Save or Discard on the page, then Save & rebuild.
Apply split to all locations is greyed out	”Save or discard your changes first”: the group panel has unsaved settings.	Click Save & rebuild in the group panel first.
The shares I typed changed after saving	They didn’t add up to 100%, so they were scaled to 100% in proportion.	Nothing to fix: the group always plans its full forecast. Use Normalize to see the result before saving.
After launch says “Not enough sales yet”	The group has sold for fewer than 14 days or fewer than 30 units at this location.	Wait for more sales. Each location is counted on its own.
Use actual mix isn’t there	The plan is Locked, Completed or Cancelled. A Locked plan says “Unlock the plan to change the split.”	Release a Locked plan, or Reopen a Completed one, to change the split.
My earlier weeks didn’t change after a new split	After launch, changes apply from today on purpose, so plan analytics stays honest.	Nothing to fix. Type into a past week yourself if you really need to change it.
I can’t open a size’s panel	Sizes have no panel of their own; everything is managed on the group’s panel.	Open the group row’s expander. To move one size’s launch date, use the Volume & launch tab.
Scanned or uploaded sizes came in as individual products	Scans, spreadsheets and forecast views always add individual products.	Add the sizes with Browse products, or use the group card’s Add variants in the wizard.