Planning and Smoothing Seasonal Fluctuations in Sales

Why seasonal fluctuations cost more than the slow period

For many businesses, seasonal fluctuations are so natural that they are no longer seen as a problem. The heating contractor has too much to do in winter, the landscaper in spring, the tax practice before filing deadlines. What is overlooked are the costs on both sides of the curve: at the peak, orders are lost because nobody has time, overtime becomes expensive, and mistakes become more frequent. In the slow period, the business pays employees who are not fully utilized and accepts orders with weak contribution margins to fill the time.

The question this article sets out to answer: how does a small business plan for seasonal fluctuations so that they cost less revenue, margin, and liquidity, and where is it worth smoothing them? To answer it, we first clarify the terms and measure the seasonal curve, then present the mental model of the two basic strategies according to Sasser, weigh them, and finally arrive at levers for sales, capacity, and money.

A season is not fate but a pattern. And patterns can be planned.

Terms: seasonality, seasonal index, peak and slow period

Seasonality refers to a pattern that repeats similarly every year, for example because weather, deadlines, holidays, or customers’ budget cycles determine demand. It must be distinguished from random fluctuations, which follow no pattern, and from a trend, a longer-term increase or decrease.

The seasonal index makes the pattern measurable. It relates the value of a month or quarter to the average of all months or quarters. An index of 130 means the quarter is 30 percent above average; an index of 75 means it is 25 percent below. For a reliable index, at least two, preferably three years should be analyzed so that chance effects even out.

It is not only revenue that needs measuring. For planning, three curves matter: inquiries, because they show when customers have a need; hours worked, because they show utilization; and incoming payments, because they determine liquidity. The three curves are offset from each other, and the real problem often lies precisely in this offset.

Determining your own seasonal curve

1. Collect data

   Export inquiries, order hours, and incoming payments per month for the last two to three years from accounting, time tracking, and the inquiry list.

2. Calculate the average

   For each curve, calculate the monthly average over the whole period.

3. Calculate the index

   Divide each monthly value by the average and multiply by 100. Average the index values of the same months across the years.

4. Overlay the curves

   Plot inquiries, hours, and incoming payments in one chart. Pay attention to the gaps between the peaks.

5. Note the causes

   Next to each peak and each slow period, write the reason: weather, deadlines, customers’ budgets, holidays. Only known causes can be influenced.

In the example, about 250 hours a month are missing at the peak, and about 210 hours remain unused in the slow period. Over the year, the business would have enough capacity. It just has it at the wrong time. How to plan hours week by week is described in the guide capacity planning.

The mental model: chase demand or keep capacity level

In 1976, W. Earl Sasser described why seasonal fluctuations hit service providers harder than manufacturers. Services cannot be produced for inventory. An hour a technician does not work in August cannot be sold in December. Manufacturers can produce ahead in slow periods; service providers cannot. For this problem, Sasser names two basic strategies.

For both strategies, Sasser names levers. On the demand side, these are different prices by timing, deliberately building demand in the off-season, complementary services that are in demand during slow periods, and appointments booked in advance. On the capacity side, they are part-time staff, particularly efficient working at the peak, customer participation, capacity shared with other businesses, and employees who can handle several tasks.

Sasser draws his examples from restaurants, hotels, and airlines of the 1970s. Klassen and Rohleder (2001) later brought together research from operations and marketing and emphasize that capacity and demand management are best planned together. That is the real lesson for small businesses: seasonal planning is neither solely a matter of scheduling nor solely a matter of sales.

Two views: absorb the peaks or fill the troughs

Flexibility speaks for chasing demand. A business that works with temporary staff, overtime, and partners at the peak carries no idle costs in the slow period. In industries with very pronounced seasons, such as landscaping, this is often the only economic solution.

The skills shortage speaks for keeping capacity level. Good specialists cannot be hired for three months and then let go, and temporary staff rarely reach their quality. A stable team is a strength that a business should not sacrifice for the peak. But if you want to keep it, you have to fill the troughs, or stability becomes expensive.

For most small B2B businesses I consider a mix to be right, with a clear emphasis on filling the troughs. The reason lies in contribution margin: an hour filled with plannable work in the slow period costs hardly anything extra, because the team is paid anyway. An hour bought in at the peak costs a premium. Peaks should therefore be absorbed with additional capacity only to the extent that demand cannot be shifted.

Levers in sales: shifting demand into the off-season

The most effective levers lie in your own offering. Four have proven particularly useful for small businesses.

The first lever is usually the strongest because it costs nothing. If you have maintenance contracts, you can place the appointments in the quiet months. The guide building recurring revenue describes how such contracts are set up. The second lever is a form of price differentiation by timing which, according to the analysis price differentiation, is easy to justify because the difference is visible to every customer and they choose for themselves.

For sales, this means: prospecting should not start when the slow period arrives, but two to three months before. Inquiries for the off-season need lead time. If you plan sales targets by month, as the guide planning sales targets describes, you should factor the seasonal curve into weekly activities.

Seasons and liquidity: planning the pre-financing

The season affects not only utilization but money. At the peak, material purchases and overtime rise, while incoming payments follow only weeks later. The article growth and cash flow describes this gap with the cash conversion cycle: days inventory plus days receivables minus days payables. In a seasonal business, the gap opens at the same time every year, and it does so before the revenue peak, not during it.

Lundmark, Coad, Frankish, and Storey (2020) show that fluctuations are dangerous. They analyzed account data from 6,578 young companies in the UK over ten years and found that strongly fluctuating monthly revenues predict later exit. The article why young companies fail describes the study in more detail. It concerns young companies and does not distinguish between seasonal and random fluctuation. But a predictable pattern is easier to manage than a random one, provided it is actually planned for.

• The seasonal curve of inquiries, hours, and incoming payments is known.
• The liquidity requirement before the peak has been calculated and covered by a reserve or credit line.
• Installment payments have been agreed for larger orders at the peak.
• Material purchasing for the peak has been coordinated with suppliers on payment terms.
• Prospecting for the off-season starts two to three months before the slow period.

Conclusion: plan the season instead of enduring it

How does a small business plan for seasonal fluctuations so that they cost less, and where does smoothing pay off? It first measures its own seasonal curve for inquiries, hours, and incoming payments, then decides deliberately how far it follows demand with additional capacity and how far it shifts demand into the off-season, and plans the pre-financing before the peak. Smoothing pays off above all where plannable services such as maintenance can be shifted and a permanent team is paid during the slow period anyway. Sasser’s distinction between chasing and leveling provides the framework; research on revenue volatility provides the reason to take it seriously.

1. This week: Export inquiries, hours, and incoming payments for the past two years by month and calculate the seasonal index.
2. Next month: Decide which plannable services will be shifted into the slow period and write it into the contracts.
3. Before the next peak: Calculate the liquidity requirement and agree on installments and credit lines in good time.

The season comes back every year. That is its disadvantage and at the same time its advantage: you know when it is coming.