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 agents does a travel agency call center need?

A travel agency handling 75 calls per hour with 5-minute AHT at 80/20 service level needs about 12-14 raw agents, or 17-20 after shrinkage. During booking season (Jan-Mar), plan for 40-50% higher volume.

What AHT should I expect for travel booking calls?

The median is about 5 minutes (300 seconds), but variance is very high. Simple domestic hotel bookings average 3-4 minutes, while complex international itineraries with multiple components can exceed 15 minutes. Group travel bookings are even longer. Weight your AHT based on your actual call mix.

How do I handle travel disruption call spikes?

Travel disruptions are unpredictable and intense. Pre-identify overflow resources: cross-trained agents from other departments, outsourcing partners on retainer, and after-hours coverage. Set up priority routing for travelers currently in transit vs. future bookings. Use IVR messages to communicate known disruptions and reduce call volume.

Should booking and support calls be in separate queues?

Yes, if your volume supports it. New booking calls are longer, require more product knowledge, and are revenue-generating. Post-booking support (changes, cancellations) is typically shorter and more procedural. Blending them makes Erlang C calculations less accurate and can frustrate booking callers with long waits caused by support volume.

How do I staff for travelers in different time zones?

If you serve international travelers, consider extended hours or 24/7 coverage. A traveler stranded at midnight their time needs immediate help. Options include follow-the-sun staffing across offices, overnight skeleton crews with escalation protocols, or AI-powered agents for basic rebooking and information during off-hours.

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Travel & Tourism

Travel Agency Call Center Staffing Calculator

Erlang C calculator with travel and tourism benchmarks. Plan staffing for booking season, itinerary support, and emergency travel assistance.

Start Calculating

Seasonal Planning:

Standard call volume — no seasonal adjustment applied

Call Center Parameters

Calls Per Hour75

Total incoming calls per hour across all lines

Average Handle Time (AHT)5m

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.30%

Typical range: 25-35%

Cost Per Agent Per Hour (optional)

Fully loaded cost for monthly cost estimate

Agents Needed

9 raw + 4 for shrinkage

Service Level

80.36%

Avg Speed of Answer

25.7s

Occupancy

69.44%

Probability of Wait

23.6%

Immediate Answer

76.4%

Traffic Intensity

6.25 Erlangs

Estimated Staffing Cost

Per Hour

$247

Per Month (160 hrs)

$39,520

Travel & Tourism Benchmarks

AHT Range

3m – 9m

Median: 5m

Service Level Standard

80/20

Occupancy Target

72-82%

Acceptable Abandonment

< 5%

Typical Shrinkage

28-34%

Source: ASTA Travel Industry Contact Center Benchmarks, 2025

Call Center Staffing for Travel & Tourism

Travel and tourism call centers handle complex, high-value transactions that require extensive product knowledge. A single booking call might involve multi-destination itineraries, airline connections, hotel arrangements, car rentals, travel insurance, and visa requirements. These calls are inherently long and require agents who can navigate multiple systems while maintaining a consultative, service-oriented approach.

Seasonality is one of the biggest staffing challenges. The "booking wave" — when consumers plan and book future travel — peaks from January through March. Summer months see a different type of volume: last-minute changes, cancellations, and emergency assistance from travelers already in transit. Each seasonal pattern requires different agent skills and different staffing levels.

External disruptions create the most challenging staffing scenarios. Flight cancellations, weather events, geopolitical incidents, and health emergencies can spike call volume 3-5x within hours. These disruption events require agents who can handle frustrated, sometimes stranded travelers while managing complex rebooking across multiple providers. Having a contingency staffing plan is essential for any travel operation.

Key Challenges

•Complex multi-component bookings (flights, hotels, cars, activities) extend AHT
•Dual seasonality: booking season (Jan-Mar) and active travel season (Jun-Aug)
•Travel disruptions (weather, cancellations) create unpredictable 3-5x surges
•Agents need destination knowledge across hundreds of locations
•Time zone coverage required for travelers worldwide

Common Call Types

New trip booking and planningItinerary modifications and changesCancellation and refund requestsTravel disruption rebookingTravel insurance inquiriesDestination information requestsLoyalty program and points redemption

Staffing Tips

1Model booking season (Jan-Mar) and travel season (Jun-Aug) as separate staffing plans — call types and AHTs differ
2Build a disruption response plan with identified overflow agents, extended hours triggers, and priority routing
3Invest in destination training during shoulder seasons when agents have more time between calls
4Consider time zone-based scheduling if serving international travelers — 24/7 coverage may be needed
5Track booking value per agent alongside call metrics — a longer call that books a $10K trip is more valuable than a shorter one

Compliance Note

PCI-DSS compliance for payment processing. DOT regulations for airline ticket disclosures. Travel insurance disclosure requirements. GDPR compliance for European traveler data.

FAQ

Travel & Tourism Staffing FAQ

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Call Optix analyzes every travel booking call — tracking conversion rates, identifying where complex itineraries stall, and coaching agents on upselling premium experiences. Maximize the value of every customer conversation.

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