How many agents does it take to handle 100 calls an hour?

With a 240 second average handle time and an 80/20 target, Erlang C puts 10 agents on the phones, delivering an 86.8 percent service level and a 12.6 second average speed of answer. After 30 percent shrinkage for breaks, meetings, training, and absence, that means 15 scheduled agents.

What happens if only 9 agents are on the phones for 100 calls an hour?

Service level drops from 86.8 to 74.2 percent and the average speed of answer rises from 12.6 to 32.2 seconds, so one agent below the Erlang C minimum misses the 80/20 target outright. At 8 agents the queue degrades to a 52.3 percent service level with callers waiting 95.9 seconds on average.

How many erlangs is 100 calls per hour?

At a 240 second average handle time, 100 calls an hour is 24,000 seconds of workload, or 6.7 erlangs of offered load. You cannot staff with 7 agents though, because random arrival clumping means even 8 agents only achieves a 52.3 percent service level. It takes 10 agents on the phones to hold an 80/20 target.

What is the fastest way to need fewer agents for 100 calls an hour?

Cut handle time. At this volume each added minute of AHT costs about two agents on the phones, so every 30 seconds trimmed from wrap-up, hold, or slow systems recovers roughly one agent in every staffed hour. The spread runs from 8 agents at a 3-minute AHT to 14 at 6 minutes, all against the same 80/20 target.

Why schedule 15 agents when only 10 are needed on the phones?

Shrinkage. At 30 percent, breaks, meetings, training, and absence consume almost a third of paid time, so 10 divided by 0.7 gives 14.3, which rounds up to 15 scheduled agents. Agents on the phones and scheduled agents are different numbers, and confusing them is the most common way this staffing plan fails in practice.

The call center staffing ladder

Call center staffing

How many agents do you need for 100 calls an hour?

10 agents on the phones, 15 on the schedule, and a service level cliff hiding one absence away.

The short answer

Handling 100 calls an hour at a 4-minute average handle time with an 80/20 service level takes 10 agents on the phones; at 30 percent shrinkage you schedule 15.

Calls per hour: 100
Offered load: 6.7 erlangs
Agents on phones: 10
Scheduled agents: 15
Service level hit: 86.8%
Occupancy: 66.7%

Why the math lands there

One hundred calls an hour at a 240 second average handle time is 24,000 seconds of conversation per hour, which is 6.7 erlangs of offered load. Ten agents on the phones clears that at an 86.8 percent service level with a 12.6 second average speed of answer. The gap between 6.7 erlangs of work and 10 people exists because calls arrive in clumps, not on a metronome, and the queue punishes anyone who staffs to the average.

This is the volume where Erlang math looks least like a straight line. Take one agent away and the service level falls from 86.8 to 74.2 percent while the average wait jumps from 12.6 to 32.2 seconds. Take away two and you are at 52.3 percent with callers holding 95.9 seconds on average. Add an eleventh instead and you buy 93.6 percent and a 5.1 second answer. Around the target, a single head swings the whole day.

Ten agents on the phones is not ten on the schedule. At 30 percent shrinkage, breaks, meetings, training, and absence eat almost a third of paid time, so you need 15 scheduled agents to keep 10 seats filled through the hour. At smaller volumes that ratio can feel like padding. At 100 calls an hour, with the cliff one sick call away, the five extra bodies are not waste. They are the plan.

1100 calls an hour times 240 seconds of handle time is 6.7 erlangs of offered load: 6.7 hours of phone work arriving every hour.
2Counting up from 7 agents, 10 is the first count where Erlang C clears the 80/20 target: 86.8 percent of calls answered within 20 seconds, with an average wait of 12.6 seconds.
3At 10 agents, occupancy is 66.7 percent: the share of each logged-in hour spent handling calls rather than waiting for the next one.
4Breaks, meetings, training, and absence take agents off the phones for 30 percent of paid time, so keeping 10 on the phones means scheduling 15.

One agent either way

Erlang math is a cliff, not a slope. This is the same hour with one or two agents more or fewer on the phones.

Agents on phones	Answered in 20s	Average wait	Occupancy
8	52.3%	95.9s	83.3%
9	74.2%	32.2s	74.1%
10the answer	86.8%	12.6s	66.7%
11	93.6%	5.1s	60.6%
12	97.1%	2.1s	55.6%

If your handle time or target differs

Agents on the phones for 100 calls an hour, across handle times and the two most common service level targets. Adjust every input live in our Erlang C calculator.

Average handle time	80/20 target	90/30 target
3 minutes	8 agents	9 agents
4 minutesthis page	10 agents	11 agents
5 minutes	12 agents	13 agents
6 minutes	14 agents	15 agents

Scheduled headcount sits above every number here: this page assumes 30 percent shrinkage, and your own rate comes out of our shrinkage tool.

What Erlang C does not tell you

Erlang C assumes 100 calls arrive at a steady random trickle across the whole hour and that nobody hangs up. Real hours are lumpier. The burst after opening or the spike after an outage email runs hotter than the model, and the 86.8 percent it promises at 10 agents is an average over the hour, not a floor within it. The 6.8 point cushion above your 80 percent target is your only shock absorber, so know it exists and do not spend it twice.

The marginal table is the real management lesson at this volume. Planned shrinkage of 30 percent covers the average rate of absence, not its clustering, and absence clusters on Mondays and the day after a holiday. An absence or two beyond plan puts you at 9 or 8 on the phones, which the table prices at 74.2 or 52.3 percent service level. At 100 calls an hour, intraday recovery, moving a break, pulling someone off email, matters more than forecast precision.

Occupancy at 10 agents runs 66.7 percent, and the temptation is to trade the apparent idle third for headcount. The marginal table prices that trade precisely: the ninth agent's departure costs 12.6 points of service level, so the cheaper fix for utilization at this volume is giving the team preemptible work like email or chat, never removing the tenth chair.

The agent count is the input; the schedule is the work. Turning 15 scheduled agents into shifts that follow your call curve, respect breaks, and survive swaps is what Soon builds automatically, with intraday coverage tracking when the forecast misses.

Frequently asked questions

How many agents does it take to handle 100 calls an hour?: With a 240 second average handle time and an 80/20 target, Erlang C puts 10 agents on the phones, delivering an 86.8 percent service level and a 12.6 second average speed of answer. After 30 percent shrinkage for breaks, meetings, training, and absence, that means 15 scheduled agents.
What happens if only 9 agents are on the phones for 100 calls an hour?: Service level drops from 86.8 to 74.2 percent and the average speed of answer rises from 12.6 to 32.2 seconds, so one agent below the Erlang C minimum misses the 80/20 target outright. At 8 agents the queue degrades to a 52.3 percent service level with callers waiting 95.9 seconds on average.
How many erlangs is 100 calls per hour?: At a 240 second average handle time, 100 calls an hour is 24,000 seconds of workload, or 6.7 erlangs of offered load. You cannot staff with 7 agents though, because random arrival clumping means even 8 agents only achieves a 52.3 percent service level. It takes 10 agents on the phones to hold an 80/20 target.
What is the fastest way to need fewer agents for 100 calls an hour?: Cut handle time. At this volume each added minute of AHT costs about two agents on the phones, so every 30 seconds trimmed from wrap-up, hold, or slow systems recovers roughly one agent in every staffed hour. The spread runs from 8 agents at a 3-minute AHT to 14 at 6 minutes, all against the same 80/20 target.
Why schedule 15 agents when only 10 are needed on the phones?: Shrinkage. At 30 percent, breaks, meetings, training, and absence consume almost a third of paid time, so 10 divided by 0.7 gives 14.3, which rounds up to 15 scheduled agents. Agents on the phones and scheduled agents are different numbers, and confusing them is the most common way this staffing plan fails in practice.

How many agents do you need for 200 calls an hour?

17 agents on the phones, 25 on the schedule, and exactly one point of margin over the 80/20 target.

17 on phones · 25 scheduled · 80/20

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How many agents do you need for 100 calls an hour at a 90/30 service level?

11 agents on the phones, 16 scheduled at 30 percent shrinkage, and only one more head than the same line at 80/20.

11 on phones · 16 scheduled · 90/30

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How many agents do you need for 100 calls an hour with a 6-minute handle time?

At this volume, every 30 seconds of average handle time is roughly one more agent on the phones.

14 on phones · 20 scheduled · 80/20

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