What are call center metrics?
Call center metrics are the numbers that show how well a floor is using its people, its data and its phone time. The core ones are average handle time, occupancy, shrinkage, abandon rate, contact rate, transfer rate and cost per transfer. Each has a simple formula, and together they tell you where money is being lost.
In BPO language these are often called KPIs, key performance indicators, and every client contract will name a few. On an outbound transfer floor in Pakistan or India working US campaigns, the most important ones are different from an inbound support center. You care less about first call resolution and more about how many dials it takes to produce one billable transfer. This post lists the metrics that matter, with formulas, and how to use them. For a shorter list focused only on transfers, see our post on KPIs for a transfer floor.
Average handle time (AHT)
Formula: AHT = (total talk time + total hold time + total after-call work) / number of calls handled.
AHT tells you how long each handled call takes from start to finish. On a fronting floor, a very low AHT can mean fronters are rushing or disqualifying too fast, and a very high one can mean they are stuck on calls that will never qualify. Look at AHT by disposition: transfers, not interested, not qualified. That is far more useful than a single number for the whole floor.
AHT also drives staffing. If you know your expected call volume and AHT, you can estimate how many seats you need. Our free AHT calculator works it out from your own talk, hold and wrap times.
Occupancy
Formula: Occupancy = time agents spend handling calls / (time handling calls + available idle time).
Occupancy shows how much of logged-in, available time agents actually spend on calls. On a predictive dialer floor it is usually high, because the dialer keeps feeding calls. Very high occupancy for long stretches leads to tired agents, worse calls and higher attrition. Very low occupancy means you are paying people to wait, often because lists are thin or the dial level is too low.
A practical range depends on the work. Outbound floors on predictive dialers often run high occupancy because the dialer controls the pace. Floors doing warm transfers need a little slack, because fronters hold the line while waiting for a closer, which counts as handling time but produces nothing until the closer answers. If that hold time grows, it shows up as higher AHT and fewer transfers per hour, not as idle time.
Watch occupancy by hour. It often drops at the start and end of the US day, when contact rates fall, and that is where moving people to callbacks or training can save money.
Shrinkage
Formula: Shrinkage = (paid hours not available for calls) / (total paid hours) x 100.
Shrinkage covers everything that takes paid agents off the phone: breaks, meals, training, coaching, meetings, sickness, absence, late logins and system downtime. A floor that plans 50 seats and forgets shrinkage will actually have far fewer on the phone at any moment.
Split it into planned shrinkage, such as breaks and training, and unplanned shrinkage, such as absence and lateness. Planned shrinkage you schedule around. Unplanned shrinkage you manage, especially on night shifts where attendance tends to be weaker. Our shrinkage calculator breaks it down so you can see which part is costing you most.
Abandon rate
Formula: Abandon rate = abandoned calls / calls answered by a person x 100. On outbound dialers it is often called the drop rate.
On an outbound floor an abandoned call happens when the dialer connects a person but no agent is free to take the call within a short time, so the call is dropped or played a message. The FTC's Telemarketing Sales Rule sets a ceiling: abandoned calls must stay under 3% of calls answered by a person, measured per campaign over a 30-day period, along with other requirements such as playing a recorded identification message. Your dialer's drop percentage setting should be kept under that limit. Our abandon rate glossary entry has more detail.
On inbound queues and closer queues, abandon rate means callers hanging up before an agent answers. For a transfer floor, that is the number to watch on your closer queue, because every abandoned transfer is a qualified caller you paid to generate and then lost.
Contact rate and connect rate
Formula: Contact rate = live human contacts / total dials x 100.
Contact rate tells you how often a dial reaches a real person rather than voicemail, a busy signal, a disconnected number or an answering machine. It depends heavily on data quality, time of day, caller ID reputation and how often each number has been called. A falling contact rate on a list you have worked hard is normal. A falling contact rate across all lists usually means caller ID problems or spam labeling.
Connect rate is related but broader: the share of dials that are answered at all, including by machines. Track both, because a high connect rate with a low contact rate means your answering machine detection or list quality needs attention.
Several things lift contact rate without buying new data: calling at the right local time for each time zone, keeping caller IDs healthy and registered, limiting attempts per number per day, and removing numbers that have been disconnected. Track it by hour and by list, and retire lists once they stop paying for the seat time they use.
Transfer rate and billable rate
Formula: Transfer rate = transfers / live contacts x 100. Billable rate = billable transfers / total transfers x 100.
Transfer rate shows how well fronters turn contacts into qualified handoffs. Billable rate shows how many of those transfers the buyer accepts and pays for, usually after a minimum call duration and a quality check. Always read the two together. A transfer rate that rises while the billable rate falls means weaker calls are being pushed through, and the buyer will notice before you do.
Break both down by fronter, by list and by hour. One fronter with a high transfer rate and a low billable rate is a coaching conversation. One list with both low is a data problem.
Cost per transfer
Formula: Cost per billable transfer = (seat cost + data cost + dialing and telecom cost + overheads) / billable transfers.
This is the number the business runs on. Revenue per billable transfer minus cost per billable transfer is your margin. Every other metric on this list matters because it moves this one: higher shrinkage means more paid hours per transfer, lower contact rates mean more dials and data per transfer, lower billable rates mean more cost spread across fewer paid transfers.
Calculate it per campaign and per data source at least weekly. Owners are often surprised to find that a cheap list costs more per billable transfer than an expensive one once seat time is counted. This is also where automation shows up clearly. B3 Voice Fronter bots are a flat $40 per bot per month with unlimited calls and no per-minute charge, so you can put the bot cost into this formula directly and compare it with human fronter seats on the same lists. See pricing for the details.
Quality score, dispositions and the metrics clients check
Formula: QA score = points achieved on the scorecard / total possible points x 100, averaged across reviewed calls.
Numbers alone do not tell you whether calls were made properly. A QA score comes from reviewers listening to a sample of calls and scoring them against a checklist: correct opener, every qualifier asked, no false claims, clear transfer line, proper handling of opt-outs. Clients in BPO contracts often set a minimum QA score, and buyers of transfers will drop vendors whose calls do not meet their standards.
Dispositions feed every other metric, so they have to be accurate. If fronters pick "not interested" for calls that were really answering machines, your contact rate looks better than it is and your list decisions go wrong. Keep the disposition list short and clear, train new hires on it, and spot-check it against recordings. Review disposition counts weekly by fronter to spot anyone whose mix looks very different from the rest of the floor.
Other metrics clients sometimes ask for include right party contact rate, average speed of answer on inbound lines, first call resolution for support work, and attrition. Use the ones in your contract, but do not let them crowd out the four numbers that decide whether you make money: contact rate, transfer rate, billable rate and cost per billable transfer.
How many agents do you need? Erlang and staffing
Once you know call volume, AHT, shrinkage and the service level you want, you can work out staffing. The classic method is the Erlang C formula, which estimates how many agents you need to answer a given share of calls within a target time. It is mostly used for inbound queues, which on a transfer floor means your closer queue.
You do not need to do the maths by hand. Our free Erlang calculator takes your calls per hour, AHT and target service level and gives you the number of agents, before and after shrinkage. Use it to check whether your closer team can take the transfers your fronters or bots will send. If it cannot, adding more fronting capacity just raises your abandon rate on the closer queue.
Review all of these metrics together every week. A single metric on its own can mislead; the pattern across them tells you where to act first.
