What does phasing a sales plan mean?

Phasing a sales plan means distributing a season's total planned sales across its individual weeks or months in the shape demand is expected to take, rather than spreading it evenly. It is the step that converts a single seasonal number into a plan that can be traded against, because every downstream figure — the inventory target, the receipt plan, the open-to-buy position — is derived from when sales are expected, not just how many.

How do you build a phasing curve?

Start from prior-season actual weekly sales, restated onto the current retail calendar so the weeks line up. Convert each week to a percentage of the season total, which gives a shape independent of the size of the year. Then adjust that shape deliberately for known differences — moving holidays, a changed promotional calendar, a different delivery schedule, weeks that were distorted by stock-outs — and apply the adjusted percentages to this season's planned total.

Why not just divide the season total evenly by the number of weeks?

Because the inventory plan is derived from the sales plan. An even split produces a flat inventory requirement, which means receipts arrive evenly while demand peaks — under-stocked through the peak and over-stocked at the exit. The season total can be exactly right and the brand still loses sales in the weeks that mattered and takes markdowns on what is left. Phasing is what makes a total actionable.

Should full-price and markdown sales be phased separately?

Yes. They are driven by different things and they peak at different times. Full-price sales follow demand and the delivery calendar; markdown sales follow the clearance plan and the season exit. Blending them into one line makes the margin plan unauditable, because a period can hit its sales number entirely on discounted units and nothing in the plan distinguishes that from a healthy week until the margin arrives.

How do you handle a week that was distorted by a stock-out last year?

Treat last year's figure for that week as contaminated rather than as demand. A stocked-out week records what was available to sell, not what customers wanted, so using it as a phasing input teaches the plan to under-buy the same week again. The usual correction is to interpolate the week from its neighbours or from the same week two years prior, and to flag it so the adjustment is visible rather than silently baked into the curve.

How granular should phasing be — weekly or monthly?

Weekly for any business trading in-season against the plan, monthly only where decisions are genuinely made monthly. The test is the decision cadence rather than the reporting cadence. Monthly phasing hides the within-month distribution, and inventory arrives against weeks, not months — a receipt that lands in the last week of a month is a very different position from one that lands in the first, and a monthly grid shows both as the same.

How to Phase a Sales Plan Across a Season

Phasing a sales plan means distributing a season total across its weeks in the shape demand will actually take. This guide covers building the shape from restated history, adjusting for calendar shift and known events, splitting full-price from markdown sales, and the phasing errors that produce a plan that balances and still misses.

What phasing is

Phasing a sales plan is distributing a season's total planned sales across its individual weeks in the shape demand is expected to take. It is a single step in merchandise financial planning, and it is the step everything downstream depends on.

That dependency is the reason it matters more than it sounds. The inventory plan is derived from the sales plan through a stock-to-sales or weeks-of-supply target. The receipt plan is then solved from the inventory plan. So an error in phasing does not stay in the sales line — it propagates into what gets bought and when it arrives, and by the time it surfaces the goods are committed.

Why an even split fails

The temptation with a season total is to divide it by the number of weeks. It is fast, it is defensible as a starting point, and it produces a plan that balances perfectly.

It also produces a flat inventory requirement. If planned sales are the same every week, the stock-to-sales calculation returns roughly the same inventory target every week, and the receipt plan flows goods in evenly across the season. Real demand is not flat — it builds, peaks and declines. So the evenly-phased plan is under-stocked through the peak, where the money is, and over-stocked at the exit, where it becomes markdown.

The season total can be exactly, precisely right and the brand still loses full-price sales in the weeks that mattered and clears the residue at a discount. That is the whole argument for phasing: the total is a budget, the phasing is the plan.

Building the shape

The method that works is to derive a shape from history and then argue with it deliberately.

Start from prior-season actual weekly sales. Actuals, not last year's plan — the plan records what was intended, and if it had been right there would be nothing to learn from.

Restate onto the current retail calendar. This is the step most often skipped and it is not optional in a shift year. Aligning by week number when a 53rd week or a moving holiday has changed the mapping puts a holiday peak into a normal week. The mechanics are covered in the retail calendar guide; the short version is to realign the anchor events explicitly before using the shape.

Convert each week to a percentage of the season total. This is what makes the shape reusable. A curve expressed in dollars only works for a year of that size; a curve expressed in percentages applies to any total, which is what lets you change the season plan without rebuilding the phasing.

Adjust for known differences, one at a time, with a reason recorded for each. A moved holiday. A changed promotional calendar. A delivery landing three weeks earlier than last year. A new channel opening mid-season. Each adjustment should be a deliberate act with a stated justification, because next year someone will want to know why week 19 is 3.1% and not 2.6%.

Apply the adjusted percentages to this season's total. The arithmetic is trivial; every judgement was made in the step before.

Keep the percentage curve as a named, reusable object rather than as a column of numbers inside one season's workbook. A curve that survives the season becomes an asset — it accumulates the corrections made each year — where a column of numbers gets rebuilt from scratch annually and loses everything learned.

Contaminated weeks

Prior-year actuals contain a specific and common lie: a week where the product was out of stock records what was available to sell, not what customers wanted to buy.

Feed that week into a phasing curve and it teaches the plan to buy light in exactly the week that sold out. Do it two years running and the curve encodes a permanent dip where the real demand has a peak. This is one of the more reliable ways for a planning process to make the same mistake repeatedly while looking data-driven the whole time.

The correction is to identify stocked-out weeks before building the curve and treat them as missing data rather than as observations. Interpolate from the surrounding weeks, or from the same week two years prior, and flag the substitution so it stays visible. The flag matters as much as the fix: an interpolated week is an estimate, and next year's planner should be able to see that it was one.

The same treatment applies to any week distorted by something that will not repeat — a site outage, a delayed delivery, a one-off promotion, a store closure.

Splitting full-price from markdown

A single blended sales line is the most common shortcut in phasing, and it costs more than it saves. Full-price and markdown sales are driven by different things and peak at different times.

Full-price sales follow demand and the delivery calendar: they build as the assortment lands and peak with the season. Markdown sales follow the clearance plan and the exit: they are near zero early and rise steeply at the end. Phasing them as one line produces a curve that describes neither.

The practical cost shows up in-season. A period can hit its blended sales number entirely on discounted units while full-price demand is running well behind, and a blended plan cannot see the difference — the variance report shows the week on plan. The margin arrives a month later and nobody can say which week it went wrong in.

Two lines, phased separately, make the markdown plan explicit as a dated intention rather than a residual. That is also what makes the season exit plannable instead of discovered.

Phasing errors that survive review

Each of these produces a plan that balances, reconciles, and reviews cleanly.

Phasing at monthly grain for a business that trades weekly. Inventory arrives against weeks. A receipt landing in the last week of a month and one landing in the first are very different positions, and a monthly grid renders both identically. Phase at the grain you make decisions at.

Copying last year's shape without restating the calendar. Covered above; it is worth listing separately because it is the single most frequent cause and it is invisible at the moment it happens.

Letting the curve absorb the growth target. If the season total is up and the shape is applied unchanged, every week is up by the same percentage — which asserts that growth will arrive evenly across the season. Sometimes true, often not. Growth from a new channel, a new door or a new category has its own timing, and it belongs in the shape rather than smeared across it.

Phasing the plan and not the comparison. A phased plan read against an unphased prior year produces variance that is pure calendar. Both sides of a comparison have to sit on the same calendar and the same shape.

Treating the phased plan as final. Phasing is an estimate of timing made before the season starts, which makes it the part of the plan most likely to be wrong and the part most worth revisiting. Reforecasting updates the shape, not just the total — a season running two weeks late is not a smaller season, it is a differently shaped one, and those two readings lead to opposite decisions about receipts.

Where phasing sits

Phasing happens after the season total is set and before the inventory plan is built — it is the third step of the nine in the merchandise financial planning process. Everything after it consumes its output.

Which is worth sitting with for a moment. The phasing curve is usually built quickly, from last year, by one person, in an hour. It then determines the inventory target for every period, the receipt figure solved from that target, the open-to-buy released to buyers, and the delivery dates negotiated with vendors. It is among the least deliberated inputs in the plan and among the most consequential — and closing that gap costs a couple of hours a season.