SUPSupply & productionStop 12 of 12
Workforce planning & shifts
How many people, with which skills, on which shifts, so labour capacity follows demand without constant hiring and firing.
Read atChange any time
Machines set a ceiling on capacity, but people often decide whether you reach it. Workforce planning works at two levels.
Staffing (months ahead): how many people with which skills. With seasonal demand, such as a sweets maker before Diwali or a warehouse during a sale season, there are three basic options:
- Chase: hire temporary staff for the peak and release them after. Capacity follows demand, but hiring and training cost money and new staff are slower.
- Level: keep a steady team and build stock in quiet months for the peak. Stable and skilled, but you carry inventory.
- Mix: a core team plus overtime, a few temporary workers and some pre-built stock. Most companies end up here.
Shift scheduling (days and weeks ahead): building rosters that cover the required hours. A warehouse might need 40 pickers from 6 pm to midnight during a sale but 15 on a normal Tuesday morning. Good rosters respect labour laws, maximum hours and rest days, and fairness, because people quit unfair rosters.
Cross-training makes everything easier: people who can work two or three stations let you move capacity to wherever the bottleneck is today.
Labour is also measured: units picked or produced per labour hour shows whether the plan is realistic and where training or layout changes would help.
Words to use
- Chase vs level
- Flex the workforce with demand, or keep it steady and use inventory to absorb swings.
- Cross-training
- Training people for several roles so capacity can move to where it is needed.
- Labour productivity
- Output per labour hour, such as picks per hour or units per shift.
From volume to headcount
The productive share allows for breaks, meetings, travel and waiting, which typically take a noticeable part of every shift.
Normal volume: 30,000 units picked a day. A trained picker averages 100 units an hour, and 85% of an 8-hour shift is productive, so each picker handles 680 units a day.
- Normal days: 30,000 / 680 = 44.1, so 45 pickers.
- Sale days: volume triples to 90,000, which would need 133 trained pickers.
- The plan: the 45 core pickers work 10-hour days (850 units each, 38,250 in total). Temporary staff, who manage about 70 units an hour in their first week (476 a day), cover the remaining 51,750: about 109 temps.
- Absence: if 8% of rostered people are absent on a typical day, 45 needed means about 49 on the roster.
Rostering: covering hours with shifts
Demand for people varies by hour: a warehouse might need 15 pickers in the morning and 40 in the evening during a sale. Rostering chooses how many people start each shift pattern so every hour is covered at the lowest cost, while respecting rules on maximum hours, rest days and breaks. Small cases fit in a spreadsheet; larger ones are solved as optimization problems by workforce scheduling tools.
Measuring productivity
Track units per labour hour by activity (receiving, putaway, picking, packing), against engineered standards based on time studies where possible. The measure shows whether the plan is realistic, which areas need training or layout changes, and how quickly new staff are learning.
Learning curves
New workers start slowly and improve with repetition. A classic description is the learning curve: each time cumulative output doubles, the time per unit falls to a fixed percentage of what it was, such as 80% (first observed in aircraft production by Wright in 1936). For planning, this means temporary staff hired in the peak week deliver much less than trained staff; hiring a week early for training often pays for itself.
Cross-training chains
Training everyone on every station is expensive. Research on flexibility (the same idea as Jordan and Graves’s chains for plants and products) shows that a little cross-training, arranged as a chain, captures most of the benefit: if each person can work two stations and the skills link all stations in a loop, capacity can flow to wherever the bottleneck is today. A skills matrix showing who can do what, and at what level, makes this visible to supervisors.
Labour rules, fatigue and safety
Local labour laws limit daily and weekly working hours, set rest periods and require higher pay for overtime. Beyond compliance, long shifts raise error and accident rates, so a plan that relies on weeks of 12-hour days is fragile. Peak plans should check legal limits, overtime cost and fatigue together.
Why pure chase costs more than it seems
Hiring and releasing staff with every swing in demand looks efficient on paper, but it carries hidden costs:
- recruitment and training for every peak,
- low productivity and more errors while new staff learn,
- losing experienced people who don’t want unstable work,
- reputation as an employer, which makes the next peak harder to staff.
That is why most companies run a stable core team and flex around it with overtime, temporary staff, cross-training and some pre-built stock.
Planning across the year
Workforce plans connect to S&OP: the agreed volumes and inventory build decide the hours needed month by month, and the workforce plan in turn limits what supply can promise. Holidays, festivals and harvest seasons affect both demand and staff availability.
Interview kit
Practise it out loud
Answer each question yourself before opening the model answer.
Workforce planning has a strategic layer, headcount and skills by season, and an operational layer, shift rosters. For seasonal demand I’d compare chase, level and mixed strategies on cost, quality and flexibility; usually a stable core team with overtime, temporary staff and some pre-built stock wins. Cross-training and productivity data make both levels more accurate.
A warehouse's volume triples during a two-week sale. How would you plan labour?
Forecast hourly volume by activity (receiving, picking, packing), convert it to labour hours using productivity rates, then cover the gap with overtime for the core team, temporary staff hired and trained early, cross-trained people moved to picking, and extended shifts. Also prepare by pre-picking or pre-packing best sellers where possible.
What are the risks of a pure chase strategy?
Constant hiring and layoffs cost money, new staff are slower and make more errors, morale suffers, and in a tight labour market you may not find people when you need them. That’s why most firms keep a core team and flex at the edges.
Connected stops
Where this idea feeds in, or gets its inputs from.
Sources and further reading
- Chopra, S. & Meindl, P. Supply Chain Management: Strategy, Planning, and Operation. Pearson. Chapter on aggregate planning.
- Hopp, W. J. & Spearman, M. L. Factory Physics. Waveland Press.
- Wright, T. P. (1936). Factors affecting the cost of airplanes. Journal of the Aeronautical Sciences, 3(4), 122–128.
- Jordan, W. C., & Graves, S. C. (1995). Principles on the benefits of manufacturing process flexibility. Management Science, 41(4), 577–594.