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TOP 21 Call Center Metrics: KPIs To Keep an Eye On

Tanya Omelianiuk

August 20, 2020

Modern call centers are getting really busy, even more busy than ever before. Managers have loads of data arriving through multiple channels connected by various processes. There are many kinds of businesses — and so is the number of call centers! They differ by size, type, and levels of their sophistication — from the most average phone-based inbound call centers to ultra-modern omnichannel companies.

Although there must be a clear difference in the overall operation, we can still find some crossover in call center metrics they are using. It means that — if boiled down to basics — we can focus on 21 essential call center KPIs to measure and track over time.

The Definitive List Of 21 call center KPIs

Active & Waiting Calls

Standing among the call center KPIs of primary importance, these real-time metrics show how many calls are already handled by agents (total number of active calls) and how many calls are currently on hold (total number of waiting calls). While too many waiting calls inevitably impact customer experience, there are 3 common approaches taken by managers and decision-makers to reduce their call backlog: extra staffing, agent coaching, and workflow optimization. Keeping track of all active and waiting calls, as well as their adequate proportion, can also improve some other crucial call center performance metrics, such as first response time and the average abandonment rate.

Average Handle Time (AHT)

Commonly known as a basic indicator of agent productivity, the average handle time may be equally useful when related to the call center performance metrics on customer experience. AHT shows the average time spent by the agent to complete a call using the following formula: total talk, hold, and after-call work time divided by total number of calls. The average handle time is a good indicator of customer experience and team benchmark showing which agents should have additional training or specific background to handle customer calls up to speed. 

Idle Time

Agents’ idle time will tell if the call center has any management or training issues. Naturally, agents may be idle when there are no clients to talk to. But it is also possible that the staff needs more training or motivation. To figure out if some of agents spends an extraordinary long time idle, compare their results to the average idle time within the team. Based on the numbers, you can see if it is reasonable or requires management.

Agent Utilization Rate

Recognizing that active daily communication with customers is more than very labour-intensive, managers and supervisors need to make sure that all staff members are spending time properly. The agent utilization rate can be generally estimated with the actual call volume handled divided by work capacity. Note, however, that a more accurate calculation will require a number of variables, such as idle time during breaks, lunches, coaching, sick days/vacation schedule, etc.

Calls Answered Per Hour (CPH)

This call center performance metrics can be also used as an effective measure of workforce productivity. The calculation is simple: total calls answered divided by total time range available (excluding waiting/idle time). Just keep in mind that the number of calls answered per hour is highly dependent on many different factors, for example, seasonal traffic or shift changes. 

First Contact Resolution (FCR)

Sometimes referred to as the first call resolution rate, the FCR forms a backbone in both inbound, and outbound call center performance metrics. It often reflects a general benchmark for excellence in many companies, providing a great way to measure business success and net efficiency per agent. The formula is simple: total number of closed deals/resolved issues on first call divided by total number of calls. The FCR might as well be calculated using total number of first calls, therefore providing a more accurate score with no repeat calls taken into account. But no matter what approach to employ, just make sure the CFR parameters of your choice are clearly understood by managers and agents.

First Response Time (FRT)

As the crucial metrics of every inbound call center, this Key Performance Indicator is also closely related to the service levels. The first response time is calculated as follows: total wait time of all calls divided by their total number. Keeping in mind that people understandably don’t want to wait too long, managers and decision-makers should always keep the FRT at a minimum.

Blocked Rate

This call center metrics forms the backbone of customer satisfaction and the overall communication quality. Blocked rate reflects the percentage of inbound callers hearing the busy tone, due to one of the following: no agents available, call queues are full/not configured, call center software unable to cope with the call volume. 

Average Answer Speed

The average speed of answer shows the actual amount of time commonly needed by the call center to take an incoming call during a specific time range. This inbound call center performance metrics is often used by managers to analyze the overall efficiency of their teams and understand the general degree of their accessibility to the callers.

Cost Per Call (CPC)

Commonly used as a primary indicator of call center efficiency under optimal resource allocation, the cost per call estimates the average amount spent for handling a single call. Decision-makers often employ the ideal cost per call, doing best to put their spending below a specific threshold and keep it over time. The CPC formula is quite elementary: total cost of all calls divided by their total number. Note, however, that in some companies the total cost of all calls refers to the operating expenses.

Revenue Per Successful Call

Showing just how much income will be delivered into business with each successful call, the revenue per successful call is generally related to outbound call center Key Performance Indicators. It helps decision-makers set the right targets and measure current income-generating potential, simply providing a bigger picture of potential revenue, which can be reasonably expected from a single compelling call handled by their agents.

Cost Per Contact

Much like the cost per call, the cost per contact is among the primary metrics on top of the list of call center KPIs. Calculated as a total amount spent for new contact acquisition (including investments through advertising, agent salary and other associated expenses) managers and decision-makers understand whether gaining contacts will be winning for business, or their potential cost is currently prohibitive.

Queue Time

The average time in the queue is the total time callers have to wait for live human pickup, divided by the actual number of calls taken by agents. As a decisive factor of customer satisfaction, this indicator should stay at least within an acceptable range.

Active Queue

This call center performance metrics simply shows how many active calls are currently waiting in a queue. Managers need to have an eye on active waiting calls for getting real-time insight on the general workload and making sure traffic goes in line with company targets. Agents and sales teams need to measure it as well, just to cope with their daily workflow accordingly.

Abandonment Rate

This call center metrics could be a bad sign for individual agents, or even undermine serious issues with general call management workflow. The higher it is, the more frequently customers are leaving the line. With a detrimental impact on customer satisfaction, abandonment rate should be always tracked and put below the target threshold. Otherwise, callers just leave without reaching the agent would become a common occurrence in your business.

Average After Call Work Time

As the work of your agents doesn’t necessarily end with just finishing the call, they will have to spend at least some time to update databases or fill additional information about the customer. If you want to maximize the time of efficient interaction, the average after call work time should be minimized. Software automation is among the best ways to achieve that.

Service Level

Indicating the percentage of calls taken within a custom time range of your choice, this call center KPI is commonly displayed in real-time dashboards. Service level should be visible to all — both your managers and agents — so that they can make data-driven decisions, keeping it within the accepted number of seconds.

Average Call Duration

The average call duration matters a lot, staying on top of the inbound and outbound list of call center performance metrics. The need for quality customer service 24/7 is a good motivation for managers to make the average call duration just as short as possible. In fact, however, it’s not always the right thing to do. Although extensive communications are generally less informative than concise ones, the average call duration as a success factor may differ significantly from one industry and type of business to another.

Repeat Calls

This call center KPI is closely relevant with the first call resolution, helping managers and decision-makers better understand the nature of certain recurrent issues or complex requests faced by the customers over and over again. The repeat call rate is calculated as follows: the number of calls within a specific issue divided by total number of calls handled by agents.

Hit Rate

This call center metrics provides managers with direct insight, showing how many outbound calls on their lead list are picked by potential customers. Most commonly, hit rate depends strongly on contact base quality, and the way of their lead routing/contact distribution between agents, and whether they use advanced call center software (such as predictive auto-dialer) — or handle calls manually.

Call Setup Success Rate

Unfortunately, not every call (both inbound, and outbound) will eventually have a successful connection. Call setup success rate (otherwise, CSSR) helps managers and agents set the right expectations on the rate call attempts will be successfully completed.


All the metrics above are crucial for the call center performance and development of the business in general. They can reveal all kinds of problems, from technical to managerial ones. When you work on improving one of them, others will change as well. It is a good sign, as the change shows how closely connected they are.