What is the Erlang C formula and how does it work?

Erlang C is a mathematical formula that calculates the probability of a caller having to wait in a queue, given the number of agents, call volume, and average handle time. It models the random arrival pattern of calls using Poisson distribution, making it far more accurate than simple division-based staffing estimates. The formula was developed by Danish mathematician A.K. Erlang and is the global standard for call center workforce planning.

What is the difference between Erlang B and Erlang C?

Erlang B calculates the probability of a call being blocked (receiving a busy signal) in a system with no queue — if all agents are busy, the call is lost. Erlang C, on the other hand, assumes calls will wait in a queue if no agent is immediately available. For most modern call centers with hold queues, Erlang C is the correct formula to use.

What is a good service level target for a call center?

The industry standard is 80/20 — meaning 80% of calls answered within 20 seconds. However, optimal targets vary by industry. Premium support lines may target 90/10, while cost-sensitive operations might accept 70/30. The right target balances customer experience against staffing costs.

What is shrinkage in call center staffing?

Shrinkage is the percentage of time agents are unavailable to handle calls despite being on shift. It includes breaks, lunch, training, meetings, coaching sessions, system downtime, sick leave, and other off-phone activities. Typical shrinkage ranges from 25% to 35%. Accounting for shrinkage is critical — without it, you'll be significantly understaffed.

How do I calculate my Average Handle Time (AHT)?

AHT = Average Talk Time + Average Hold Time + Average After-Call Work (ACW) time. Talk time is the actual conversation duration. Hold time is when the caller is on hold. ACW (or wrap-up time) includes note-taking, CRM updates, and any post-call tasks. Most ACD (Automatic Call Distribution) systems track these components automatically.

What is agent occupancy and what's the ideal rate?

Occupancy is the percentage of time agents spend handling calls versus waiting for calls. An occupancy rate of 80-85% is generally considered ideal. Below 70% suggests overstaffing. Above 90% leads to agent burnout, increased attrition, and degraded service quality as agents have no recovery time between calls.

Is the Erlang C formula accurate?

Erlang C is highly accurate for inbound call center planning and is the industry standard used worldwide. However, it has limitations: it assumes infinite queue capacity (no callers hang up), it doesn't account for call abandonment, and it assumes a steady-state system. For most practical purposes, these limitations are minor, and Erlang C provides excellent staffing estimates.

How often should I recalculate staffing levels?

Recalculate whenever your call patterns change significantly. Most centers review staffing quarterly and adjust for seasonal patterns. You should also recalculate when AHT changes (due to new products, policy changes, or training), when call volume trends shift, or when you change your service level targets.

What is traffic intensity in Erlangs?

Traffic intensity measures the total call workload on your system, expressed in Erlangs. It's calculated as (calls per hour × average handle time in seconds) / 3600. One Erlang represents one agent fully occupied for one hour. You always need more agents than Erlangs — for example, 10 Erlangs of traffic might require 14-15 agents to maintain an 80/20 service level.

Can I use this calculator for chat and email staffing?

Erlang C was designed for single-channel voice calls where agents handle one interaction at a time. For chat (where agents handle multiple simultaneous conversations) or email (which isn't real-time), you'll need modified approaches. However, if your chat agents handle one chat at a time, Erlang C can provide a reasonable estimate.

How many reservation agents does a 200-room hotel need?

It depends on your call volume, not room count. A 200-room hotel typically handles 60-120 calls per hour during peak periods. Use the calculator above with your actual call data. As a starting point, a property handling 80 calls/hour with 4-minute AHT and an 80/20 service level target typically needs 8-10 raw agents, or 12-15 after shrinkage.

What is a good average handle time for hotel reservation calls?

The industry median is around 4 minutes (240 seconds), but this varies significantly. Simple availability checks average 2-3 minutes, while complex group bookings can exceed 8 minutes. Calls involving upsells (spa, dining, upgrades) tend to be longer but generate more revenue, so a longer AHT isn't always negative.

How do I staff for seasonal peaks at a resort?

Use the seasonal toggle above to apply a peak multiplier. Most resorts see 40-50% higher call volumes during peak season. Start planning 6-8 weeks before peak season to allow for hiring and training. Consider a mix of full-time agents and seasonal hires, and cross-train front desk staff to handle overflow during surges.

Should I use different service level targets for different seasons?

Many properties maintain 80/20 year-round but accept 70/30 during extreme peaks if the cost of additional agents outweighs the revenue impact. The key is tracking your abandonment rate — if callers are hanging up and booking through OTAs, the lost commission far exceeds the cost of an additional agent.

How do I account for after-hours calls in my staffing plan?

After-hours call volume is typically 15-25% of daytime volume. Options include reduced overnight staffing, overflow to a third-party answering service, or AI-powered booking agents that handle reservation inquiries 24/7. Consider that after-hours callers often have high booking intent — they're planning a trip and want to finalize details.

What shrinkage rate should hotels use?

Hospitality contact centers typically see 30-38% shrinkage, higher than the industry average of 25-30%. This is because hotel reservation agents require ongoing training on promotions, rate changes, property updates, and reservation system updates. Factor in additional shrinkage for multi-property agents who need training across multiple hotels.

How do group and event bookings affect call center staffing?

Group booking calls are significantly longer (8-15 minutes) and require more skilled agents. If group inquiries make up more than 20% of your call volume, consider calculating staffing separately for group and individual reservations, as blending them can skew your AHT and lead to understaffing.

Call Optix

Integrations Pricing Customers

Call Optix

Hotel & Hospitality

Hotel Call Center Staffing Calculator

Erlang C calculator pre-loaded with hospitality industry benchmarks. Plan staffing for peak season, shoulder season, and off-peak in seconds.

Start Calculating

Seasonal Planning:

Standard call volume — no seasonal adjustment applied

Call Center Parameters

Calls Per Hour85

Total incoming calls per hour across all lines

Average Handle Time (AHT)4m

Includes talk time + after-call work

Target Service Level80%

% of calls answered within target time. Industry standard: 80%

Target Answer Time20s

Maximum wait time in seconds. Standard: 20s

ShrinkageShrinkage accounts for breaks, training, meetings, sick time, and other non-productive time that reduces agent availability.35%

Typical range: 25-35%

Cost Per Agent Per Hour (optional)

Fully loaded cost for monthly cost estimate

Agents Needed

9 raw + 5 for shrinkage

Service Level

88.65%

Avg Speed of Answer

10.8s

Occupancy

62.96%

Probability of Wait

14.99%

Immediate Answer

85.01%

Traffic Intensity

5.67 Erlangs

Estimated Staffing Cost

Per Hour

$252

Per Month (160 hrs)

$40,320

Hotel & Hospitality Benchmarks

AHT Range

3m – 6m

Median: 4m

Service Level Standard

80/20

Occupancy Target

75-82%

Acceptable Abandonment

< 5%

Typical Shrinkage

30-38%

Source: Cornell Hospitality Research, AHLA 2025 Benchmarks

Call Center Staffing for Hotel & Hospitality

Hotel call centers face unique staffing challenges due to extreme seasonality — a resort that needs 12 agents in July may only need 4 in February. Unlike general customer service centers, hotel reservation agents must handle complex multi-night bookings, upsell amenities like spa packages and room upgrades, and navigate cancellation policies, driving average handle times 30-40% higher than typical inbound support.

The revenue impact of understaffing is immediate and measurable. When guests can't reach your reservations team, they don't wait — they book through an OTA, costing your property 15-25% in commission fees. Every missed call during peak season is a direct revenue loss. Conversely, overstaffing during shoulder months erodes margins.

Effective workforce planning in hospitality requires modeling for multiple scenarios: peak season with holiday surges, shoulder periods with moderate demand, and off-peak windows where cross-training front desk staff as overflow agents becomes critical. The calculator above lets you toggle between these scenarios instantly using real hospitality benchmarks.

Key Challenges

•Extreme seasonality requiring 2-3x staffing swings
•Complex multi-night bookings with amenity upsells increase AHT
•Multilingual support needed for international properties
•Cancellation policy handling requires trained agents
•Revenue management pressure to convert every inquiry

Common Call Types

New reservationsBooking modificationsCancellations and refund requestsAmenity and upgrade inquiriesGroup and event bookingsLoyalty program questions

Staffing Tips

1Staff to peak-hour volume, not daily average — hotel calls cluster around 10am-2pm and 6pm-8pm
2Cross-train front desk staff as overflow agents during shoulder season
3Use IVR to deflect FAQ calls (directions, check-in times) and preserve agents for revenue-generating calls
4Track booking conversion rate per agent, not just call volume
5Plan 6-8 weeks ahead for seasonal ramp — hospitality has high training time for reservation systems

Compliance Note

PCI-DSS compliance required for credit card handling over phone. Call recording consent varies by jurisdiction for international properties.

FAQ

Hotel & Hospitality Staffing FAQ

Staffing is step one. Call quality is what drives bookings.

Call Optix automatically analyzes every reservation call — tracking booking conversions, extracting check-in dates and room types, and scoring agents on upsell performance. See which agents convert and why.

You've calculated how many agents you need. Now find out if those agents are actually converting callers into guests.

Learn More

Related Industry Calculators

Travel & Tourism

75 calls/hr · 5m AHT

Elder Care & Senior Living

45 calls/hr · 6m AHT

View all industry calculators