WFM guide

Contact centre scheduling guide

Q: What shift patterns are used in contact centres?

Contact centres use several shift pattern types: (1) Fixed shifts — agents work the same hours every day (e.g. 08:00–16:30 Monday to Friday). Simple to administer; poor fit for operations with variable intraday demand. (2) Rotating shifts — agents cycle through different start times on a pre-set rotation (e.g. early/late/mid on a 3-week cycle). Better coverage of intraday peaks; requires more complex scheduling. (3) Compressed hours — agents work fewer but longer days (e.g. 4×10-hour shifts instead of 5×8). Popular with agents; improves coverage on 24/7 operations. (4) Flexible start time — agents have a set shift length but can start within a window (e.g. any 30-minute slot between 07:30 and 10:00). Best fit for Erlang-optimised scheduling. (5) Split shifts — two shorter shifts in one day with a break in between. Rarely used in UK operations due to Working Time Regulations and agent preference.

Q: How do you optimise a contact centre schedule?

Schedule optimisation in contact centres involves three steps: (1) Generate the interval-level demand profile — run Erlang C on the volume forecast for each 15 or 30-minute interval to produce a required-agents-per-interval curve. (2) Build shift templates that match the peaks — design shift start times and durations that land coverage where the Erlang C curve is highest. Avoid having everyone start at the same time (creates simultaneous breaks and simultaneous end-of-shift troughs). (3) Assign agents to shifts — match the shift templates to the demand curve, distributing shift patterns equitably across the team, then filling gaps with overtime or flex resource. The goal is to minimise the total scheduled hours while keeping the achieved service level above the target in every interval.

Q: How do you schedule for weekends in a contact centre?

Weekend scheduling involves two distinct problems: (1) Volume is typically lower on weekends for most contact centre types (30–70% of Monday volume) but service level targets are identical — so fewer agents are needed. (2) Agents need rest days, and weekend days off are highly valued — distributing fair weekend coverage across the team requires a rotation or contractual obligation for weekend working. Most UK operations either include weekend working in the contract with a fixed weekend rotation (e.g. every 3rd or 4th weekend), offer a premium for voluntary weekend working, or use a split-team model (some agents work Mon–Fri; others work Tue–Sat or Wed–Sun). The key is that weekend minimum staffing floors must be met by design, not left to volunteers.

Q: What is the difference between fixed and rotating shifts in a contact centre?

Fixed shifts: agents work the same hours every day (e.g. always 08:00–16:30). Simple to understand and plan around; poor flexibility for intraday demand matching; tends to overproduce early-morning and underperform late-afternoon coverage. Rotating shifts: agents cycle through different start times on a schedule (e.g. early one week, mid the next, late the following). Better demand coverage and fairer distribution of unpopular shift times; requires agents to plan their lives around a changing schedule, which can affect engagement. Most operations settle on a hybrid: a fixed-structure week (same days of week) with rotating start times within a defined window.

Scheduling sits between forecasting and operations: it converts a volume forecast and agent headcount into a roster that delivers the right number of agents at the right time. A good schedule meets service level targets at minimum cost. A bad one overstaffs some intervals and understaffs others, sometimes on the same day.

From Erlang C to a schedule

The scheduling process in sequence

Volume forecast: Interval-level (15 or 30 min) contact volume for the scheduling period, typically one week forward

Erlang C: Convert each interval's volume + AHT + SL target into a required-agents number. This is the demand curve: how many seated agents are needed at each interval to hit SL

Seated → scheduled: Apply shrinkage uplift: divide each interval's seated requirement by (1 − shrinkage%) to get the scheduled headcount needed

Shift template design: Design shift start times, durations, and break positions that match the scheduled headcount curve. Stagger starts to align with ramp. Starting everyone at 08:00 creates a break trough at 10:30

Agent assignment: Assign agents to shifts. Apply working time rules, leave balances, and contractual constraints. Identify gaps: intervals where coverage falls below the scheduled requirement

Gap fill: Fill gaps with overtime offers, flex agent allocation, or accept residual risk and document it. Never fill gaps by ignoring the Erlang requirement

Shift pattern types

Fixed shifts

08:00–16:30, Mon–Fri

Advantages

+ Simple to administer
+ Agents can plan their personal lives easily
+ No weekly variation in break timing

Disadvantages

− Poor fit for variable intraday demand
− Creates simultaneous breaks at standard times
− Overstaffs quiet periods; understaffs peaks if misaligned

Best for: Small operations (under 20 agents); operations with flat intraday demand; back-office processing

Rotating start times

Early (07:00), Mid (10:00), Late (13:00) on a 3-week rotation

Advantages

+ Distributes intraday coverage across the day
+ Fair: no one always works the unpopular evening shift
+ Better demand fit than fixed shifts

Disadvantages

− More complex to schedule and communicate
− Agents find it harder to establish routines
− Childcare and commute conflicts increase with variation

Best for: Operations with 6am–9pm coverage; medium-to-large operations (30+ agents)

Flexible start window

7.5-hour shift starting anytime 07:30–10:30 (WFM assigns start time per week)

Advantages

+ Optimal for Erlang C demand matching: WFM assigns starts to peaks
+ Efficiency gain vs. fixed shifts can be 10 to 15% fewer agents for same SL
+ Still provides predictable shift length for agents

Disadvantages

− Requires contractual agreement for flexible start obligations
− Agents need advance notice (typically 2–4 weeks) to plan around
− More complex for agents to communicate their schedule to family/childcare

Best for: Operations committed to WFM-led scheduling; large operations (50+ agents) where efficiency gains compound

Compressed hours

4×10-hour shifts (e.g. Mon–Thu, with Fri off); or 3×12-hour shifts

Advantages

+ Extra rest day per week, which agents consistently prefer
+ Enables 24-hour coverage with fewer shift changeovers
+ Reduces commuting frequency

Disadvantages

− 10-hour shifts increase fatigue in the final 2 hours, with AHT and quality risk
− Working Time Regulations: 11-hour minimum rest between shifts must be maintained
− Breaks and lunch must be managed carefully in long shifts

Best for: 24/7 operations; agents with long commutes; operations with strong agent demand for 4-day weeks

Days off and weekend scheduling

Weekend scheduling is where most contact centres make their first scheduling compromise. The instinct is to ask for volunteers, but relying on volunteers for a structural coverage requirement produces unpredictable staffing and resentment among the agents who always volunteer.

Contractual weekend rotation

Weekend working is included in the employment contract. Agents work 1 in every N weekends (e.g. 1 in 3 or 1 in 4). The rota is set annually and published in advance. Premium pay or TOIL for weekend shifts is common. Predictable for WFM; fair if applied consistently.

Weekend premium (volunteer)

Weekend working is optional, incentivised by a premium payment (typically 1.25–1.5× weekday rate). Works when weekend volume is low enough that a fraction of the team suffices. Unreliable if weekend volume requires more volunteers than will reliably come forward.

Split workforce (Mon–Fri + Tue–Sat)

A proportion of agents have a Tuesday to Saturday contract (or Wed to Sun). Weekday and weekend teams overlap in the mid-week. Provides guaranteed weekend coverage without a universal rota. Requires recruiting agents who accept a non-standard week, which is harder in some labour markets.

Common scheduling mistakes

Synchronised break times

When all agents take their first break at 10:30, coverage drops simultaneously. The Erlang model does not account for breaks; breaks must be staggered across the interval so the seated agent count stays above the Erlang minimum at every moment.

Scheduling to the average, not the peak

If you schedule enough agents for the average volume of the day, you will be right on average and wrong during every peak. Erlang C requirements must be met at every interval. The SL target is not 'most of the time'.

Ignoring ramp-up at shift start

Agents logging in at shift start need 5–10 minutes to set up, review notes, and reach stable AHT. Scheduling 08:00 shifts to cover 08:00 volume produces an 08:00–08:10 coverage dip. Build a 10-minute ramp buffer at shift starts in high-volume periods.

Applying shrinkage to the schedule, not the seated requirement

Shrinkage converts the Erlang C seated requirement into a scheduled headcount. It belongs in that conversion step. Applying it again to the schedule (double-applying shrinkage) produces systematic overscheduling: more agents on roster than needed.

End-of-shift early departures in the Erlang count

Some agents log off early (finishing a call, then leaving). If end-of-shift cutoffs are not built into the schedule, intervals at shift boundaries are understaffed relative to the Erlang requirement. Add a 15-minute operational buffer at shift ends in high-volume periods.

Scheduling questions

What shift patterns are used in contact centres?

Fixed shifts (same hours daily), rotating shifts (different start times on a cycle), flexible start window (WFM-assigned start time within a window), and compressed hours (4×10h or 3×12h). Most operations use rotating or flexible-start patterns for intraday demand matching.

How do you optimise a contact centre schedule?

Three steps: (1) Generate the interval-level demand curve using Erlang C. (2) Design shift templates with staggered starts that match the peaks. (3) Assign agents to shifts equitably, fill gaps with overtime or flex, and confirm minimum floors are met at every interval.

How do you schedule for weekends in a contact centre?

Options: contractual weekend rotation (1 in 3 or 1 in 4 weekends, set annually); voluntary premium (incentive pay for weekend working, works when volume is low); or split workforce (some agents on Tue–Sat contracts). Volunteer-only without structure fails when weekend volume is significant.

What is the difference between fixed and rotating shifts in a contact centre?

Fixed: same hours every day, simple to plan around but poor demand fit. Rotating: agents cycle through early/mid/late starts with better coverage and fair distribution of unpopular slots, but harder for agents to establish routines. Most operations use a hybrid: fixed structure (same weekdays) with rotating start times.