Phasing a forecast across weeks to match a real selling pattern

This page explains how a factory or buyer spreads a confirmed forecast across the weeks of a season to match how a style actually sells, rather than delivering it in one lump sum

This page explains phasing: dividing a total forecast quantity into weekly delivery amounts that follow a style's own real selling pattern, instead of shipping the whole forecast in one delivery regardless of when it will actually sell. It is for a factory or buyer turning a confirmed total forecast into a week-by-week delivery plan.

At work, a factory such as Delta Garments and a buyer such as Northline Apparel agree a total forecast quantity, but a single delivery of that whole quantity on one date creates its own problem: a style that sells more heavily in the early weeks of a season needs more stock in shops early, while a style that builds steadily needs a more even supply across the season. Delivering the entire forecast at once, on one date chosen for production convenience rather than the selling pattern, risks shops running short in heavy-selling weeks while still holding excess stock in slower ones. This lesson gives you the method for phasing a confirmed forecast to match a style's own real selling pattern.

You need: lesson 3.1's forecast for Order A's own T-shirt is useful background but not required.

By the end of this lesson you can:

• state why a total forecast is phased across weeks rather than delivered in one lump sum;
• read a style's own weekly selling pattern from previous seasons and use it to set phased delivery shares;
• apply the method for converting a total forecast into weekly phased quantities using a selling-pattern percentage;
• read the forecasting and phasing worksheet's phasing sheet and say what it adds to a single total forecast figure;
• avoid the common mistake of phasing a forecast evenly across every week regardless of the style's own real selling pattern.

Not covered here: building the forecast total itself from sales history (lesson 3.1); adjusting the phased plan once real sales data starts coming in (lesson 3.3).

A total forecast is phased across a season's weeks according to a style's own real selling pattern, not delivered as one single lump sum

Phasing takes a style's own total forecast and spreads it across the weeks of a selling season in shares that match its own selling pattern: the proportion of total sales that genuinely falls in each week, based on recorded history. A style that is front-loaded, selling more heavily in its early weeks, needs a larger intake early in the season; a style that sells steadily needs a more even weekly supply instead. Phasing turns a single total number into a week-by-week plan that a factory can actually deliver against.

Phasing applies to any style with a real selling pattern, but who sets the weekly shares differs by market and model

Delta Garments phases Order A's own 14,413-piece forecast into three deliveries that follow Northline Apparel's front-loaded selling pattern

Delta Garments and Northline Apparel take the 14,413-piece total forecast from lesson 3.1 and phase it into three deliveries across the selling season, rather than shipping the whole quantity on one date. Northline Apparel's own recorded selling pattern for the style shows 45% of a season's sales in the first four weeks, 35% in the next four weeks, and 20% in the remaining weeks, a genuinely front-loaded pattern. Delta Garments phases the three deliveries to match these shares, each still fitting inside Order A's own fixed 16-week production timeline.

Order A's own 14,413-piece forecast splits into deliveries of about 6,486, 5,045 and 2,882 pieces across the three phased shares

Delta Garments applies Northline Apparel's own 45%, 35% and 20% selling-pattern shares to the 14,413-piece total forecast to size each phased delivery.

Four steps that turn a total forecast into a phased weekly or period delivery plan

1. Confirm the style's own selling-pattern shares from its recorded sales history. These shares must come from real recorded data, not an assumed even split.
2. Apply each share to the total forecast to size each phased delivery. Each delivery's own quantity is the total forecast multiplied by its own share.
3. Check every phased delivery against the factory's own fixed production lead time. A phased delivery date earlier than the lead time genuinely allows must be flagged, not assumed away.
4. Confirm all phased deliveries sum back to the original total forecast. A phasing plan that does not reconcile to the total forecast contains an error somewhere in the split.

A common mistake is phasing a forecast evenly across every week regardless of the style's own real selling pattern

A common mistake is dividing a total forecast into equal weekly or period amounts without checking whether the style's own selling pattern is actually even. If Delta Garments had phased Order A's own 14,413-piece forecast into three equal deliveries of about 4,804 pieces each, ignoring Northline Apparel's own genuinely front-loaded 45/35/20 pattern, the first delivery would undersupply the season's own heaviest-selling weeks while the third delivery oversupplies its slowest ones, the opposite of what the real selling pattern calls for.

• Phasing spreads a total forecast across a season's weeks to match a style's own real selling pattern, not an even split.
• Northline Apparel's own selling pattern for Order A's T-shirt is 45% in weeks 1–4, 35% in weeks 5–8, and 20% in the remaining weeks.
• Each phased delivery equals the total forecast multiplied by its own selling-pattern share.
• All phased deliveries must sum back to the original total forecast; if they do not, the split has an error.
• Phasing works inside a factory's own real production lead time; it cannot deliver stock before the factory can genuinely produce it.

Northline Apparel asks Delta Garments to move more of the forecast into Delivery 1, ahead of an early-season promotion

Northline Apparel plans an early-season promotion and asks Delta Garments whether Delivery 1 can be increased from 6,486 pieces to 8,000 pieces, with the difference taken from Delivery 2.

• Delta Garments' own fixed 16-week production timeline for the order has already begun, with cutting scheduled against the original three-delivery split.
• Order A's own timeline gives the factory 5 weeks for fabric before sewing can begin, a stage already committed for the current split.
• Moving 1,514 pieces from Delivery 2 into Delivery 1 would require those specific pieces to be cut and sewn on an earlier schedule than currently planned.

Should Delta Garments move 1,514 pieces from Delivery 2 into Delivery 1 to support the early promotion? Decide before you open the answer.

Forecasting and phasing worksheet: the phasing sheet this lesson fills

The workbook's "Phasing" sheet takes the total forecast from the "Sales history and forecast" sheet, applies each selling-pattern share entered by week or period, calculates each phased delivery quantity, and checks that all phased deliveries sum back to the original total forecast.

Delta Garments' own rows record the 45%, 35% and 20% shares against Order A's own 14,413-piece forecast, with the sheet calculating 6,486, 5,045 and 2,882 pieces and confirming the three sum to the original total.

Download the Forecasting and phasing worksheet (Excel)

Lesson 3.3: Adjusting a forecast once real sales data starts coming in

You now know how to phase a forecast across weeks to match a real selling pattern. The next lesson covers what happens once the season actually starts and real sales data begins arriving. Back to the course map