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What Is Service Level in a Call Center?
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When call center managers talk about whether they're "hitting service," they're usually talking about service level. It's one of the most important measures of how accessible a business is to its customers, and it plays a central role in deciding how many people need to be working at any given time.
The Definition
Service level is the percentage of calls answered within a target time.
It's usually written as two numbers. For example, a service level of 80/20 means the goal is to answer 80% of calls within 20 seconds.
The first number is the percentage of calls. The second is the time threshold, in seconds. Different businesses choose different targets, such as 90/30, 80/60, or 70/120, depending on their customers and priorities.
How Service Level Is Calculated
The basic formula is:
Service level = (Calls answered within the target time ÷ Total calls offered) × 100
For example, if 1,000 calls arrive in an hour and 820 are answered within 20 seconds, the service level is 82%.
What about abandoned calls?
One complication is how to treat callers who hang up before being answered. Different businesses handle this differently:
- Including all abandoned calls in the total, which gives a stricter measure.
- Excluding very short abandons, for example callers who hang up within five seconds, since these are often misdials.
- Counting calls abandoned within the target time as meeting the target, since the caller didn't wait longer than the threshold.
There's no single correct method, but it's important to choose one, use it consistently, and be clear about which is being used when comparing results.
Service Level vs Average Speed of Answer
Service level is often reported alongside average speed of answer (ASA), the average time callers wait before being answered. The two are related but tell different stories.
An average can hide a lot. If most callers are answered instantly but a few wait ten minutes, the ASA might still look reasonable. Service level shows how many callers had an acceptable experience, making it a better reflection of the wait most customers actually experience.
Many call centers track both, along with the longest wait time, to get a fuller picture.
Why Service Level Matters
Customer experience
Long waits frustrate customers and increase the number who hang up. Service level helps businesses keep waits within an acceptable range.
Staffing decisions
Service level is the main target used in workforce planning. Planners calculate how many agents are needed in each period, often every 15 or 30 minutes, to meet the chosen service level given the expected call volume and handle time.
Managing the day
Real-time analysts watch service level throughout the day and adjust when it starts to slip, for example by moving breaks or asking agents to switch to the phones from other tasks.
Why Small Changes in Staffing Have Big Effects
Service level doesn't change in a straight line as staff numbers change. When a team is already stretched, adding one more agent can improve service level dramatically. When a team already has plenty of agents, adding another makes only a small difference.
The reverse is also true. If a team is only just meeting its target, losing one or two people, for example through unexpected absence, can cause service level to fall sharply and queues to build quickly.
This is why accurate forecasting and good schedule adherence matter so much in call centers.
Choosing a Service Level Target
There's no universal standard. The right target depends on factors such as:
- Customer expectations. Urgent services may need faster answers than general inquiries.
- Type of call. Sales calls may warrant faster answers than routine admin.
- Cost. Higher targets require more staff and cost more.
- Alternatives available. If customers can use self-service or request a callback, longer waits may be more acceptable.
- Competitors. Customers compare their experience with other businesses.
Many businesses set different targets for different queues, such as a faster target for urgent issues.
Measuring Service Level Over Time
Service level is usually measured in short intervals, such as every 15 or 30 minutes, as well as daily, weekly, and monthly. Looking at short intervals matters because daily averages can hide problems. A call center might meet its daily target overall while missing it badly during the busiest hour, when the most customers are calling.
Common Pitfalls
Focusing only on the daily average. This can hide poor service at peak times.
Hitting the target at any cost. Pressuring agents to keep calls short in order to answer more calls quickly can harm quality and resolution.
Ignoring what happens after the threshold. A caller who waits 21 seconds and one who waits 21 minutes both "miss" an 80/20 target, but their experiences are very different. Tracking longest wait times helps.
Changing definitions. Changing how abandoned calls are counted can make results look better or worse without any real change in service.
A Measure of Accessibility
Service level answers a simple but important question: can customers reach us within a reasonable time? It's central to planning, managing, and judging how well a call center serves its customers. Used alongside measures of quality and resolution, it helps businesses make sure customers not only get through quickly, but also get the help they need once they do.