S&OP for mid-sized businesses: planning that people actually use

Sales and operations planning has a reputation problem in mid-sized firms. Someone attends a course, comes back with a five-step monthly cycle and a 40-slide pack, and six months later the meeting has quietly stopped. The process wasn't wrong. It was sized for a business with a planning department, and most mid-sized businesses have one planner and a spreadsheet.

The need hasn't gone away. It has grown. PwC's Working Capital Study 25/26 found medium-sized companies' inventory days up 24.2% over the last decade, against 5.5% for large companies. Demand has been hard to read this year: S&P Global's UK manufacturing PMI credited stockpiling ahead of price rises for part of the lift in early 2026 and then reported it fading by June. The CBI's August 2026 survey showed export order books jumping from a balance of minus 33% to zero in a single month, while total order books stayed well below normal and selling price expectations rose to +22% against a long-run average of +8%.

When demand swings like that, the business that notices first and agrees a response fastest keeps its margin and its cash. That is all S&OP is for.

The version that survives

Strip it back to what a monthly cycle must do: agree what we expect to sell, check whether we can supply it, decide what to do about the gaps, and put a cash figure on the result. Everything else is optional.

In practice that runs over the first two to three weeks of the month.

The demand review comes first, owned by the commercial director, not by the planner. Sales present expected volumes by product family, not by SKU, with the reasons for any change from last month. New customers, lost customers, promotions, price changes. If sales won't own the number, the process is dead already.

Supply comes next. Operations and procurement check the demand plan against capacity, supplier lead times and stock. They come back with the constraints and two or three options for each one, each with a cost.

Finance converts both into pounds. Revenue, margin, stock value and cash, against budget and against last month's plan. This step is the one most mid-sized processes skip, and it is the one that gets the managing director to turn up.

The decision meeting closes the cycle. Sixty minutes, the leadership team, a short pack. It agrees one plan, decides the trade-offs that the teams below couldn't, and records the decisions. If a meeting ends without a decision log, it was a briefing.

What to measure, and what to drop

Forecast accuracy is the measure everyone reaches for. Forecast bias is more useful. A forecast that is consistently 15% high fills the warehouse; one that is randomly 15% out in both directions mostly washes out. Track bias by family and by the person who owns the number.

Alongside it: customer service level, stock value against plan, and the cash effect of the month's decisions. Four measures, reported the same way every month, are enough.

Drop the detail from the executive meeting. SKU-level debate belongs in the preparation meetings and in the planning team. Drop the slide that recaps last month's sales, because everyone has seen the management accounts. Drop any measure nobody would act on.

Tools and timing

You don't need new software to start. A shared workbook with a clear owner for each tab will run a mid-sized S&OP for the first year. Buy a planning tool once the process is stable and you know what you want it to do, not before. Software bought to create a process usually ends up automating a meeting nobody attends.

Expect three to four cycles before the numbers are trusted and six before the meeting feels routine. The first real sign it is working is when a decision gets made in the room that would previously have been made by default, such as a buyer placing an order because nobody told them demand had changed. The second sign is stock. Within a year, inventory should be falling relative to sales without service suffering, and the finance director should be able to explain why.

Ownership matters more than method. Put the process under one senior person with the authority to call the meeting and hold people to their numbers. In a mid-sized business that is often the finance director or the operations director, and it works better when it isn't the planner.