Staffing Calculator — EclipseFrontiers

Methodology: This calculator uses the Erlang C formula (A.K. Erlang, 1917) — the industry standard for inbound contact centre staffing worldwide. It computes traffic intensity, models random call arrivals against agent capacity, and calculates the probability a caller must wait, expected wait time, and service level. Shrinkage is applied using the SWPP formula: Rostered FTE = Raw Agents ÷ (1 − Shrinkage%). Erlang A (Palm, 1946) models caller abandonment where average patience is below target wait time.

Volume & Handling

Call volume and handling time for your planning interval

Planning interval

Calls / contacts in interval

Average Handling Time — AHT (seconds)

Talk time + hold time + after-call work. Industry avg: 240–360s

Average Time to Abandon — ATA (seconds)

Erlang A: patience before caller hangs up. 0 = disable abandons. Industry avg: 60–120s

Service Level Targets

What level of service do you need to deliver?

Service level target (%)

% of calls answered within the target time. Industry standard: 80%

Target answer time (seconds)

The "within X seconds" part. 80/20 = answer 80% within 20s. Standard: 20s

Max occupancy target (%)

Time agents spend on calls vs available. Industry ideal: 80–85%. Above 90% causes burnout.

Shrinkage (%)

Time paid but unavailable: breaks, training, meetings, absence. Typical: 25–35%

Methodology: Shrinkage is split into External (time away from the office: holidays, sickness, lateness) and Internal (on-site but off-task: breaks, meetings, training, coaching). Formula: Shrinkage % = (Total shrinkage hours ÷ Total scheduled hours) × 100. Rostered FTE = Raw FTE ÷ (1 − Shrinkage). Industry range: 20–35%. Above 40% indicates a systemic absence or scheduling problem.

External Shrinkage

Time away from work (%).

External total: 0%

Internal Shrinkage

On-site but off-task (%).

Internal total: 0%

Shrinkage Result

Base agents required (from Erlang)

Peak staffing: Upload a CSV export from your CRM (Salesforce, HubSpot, Zendesk, Five9, etc.) containing call volume by time period, or enter data manually. The tool parses volume-by-hour/half-hour, applies Erlang C to each interval, identifies peak periods, and generates a staffing requirement heatmap. Accepted CSV formats: any file with columns containing hour/time and count/volume/calls data. Templates below if you need a starting point.

Upload CRM Volume Data

Export your call volume report from your CRM as CSV and upload here. The tool auto-detects column formats from Salesforce, HubSpot, Zendesk, Five9, Genesys, and generic exports.

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Drop CSV file here or click to browse

Exports accepted from any contact centre platform or CRM

Salesforce HubSpot Zendesk Five9 Genesys NICE Generic CSV

Manual Volume Entry — Daily Pattern

Enter expected call volume per hour for a typical day. Or use the uploaded data above.

AHT (seconds)

Service level (% / seconds)

Shrinkage (%)

Interval

Interval planning: Breaks the day into 30-minute intervals and calculates required agents for each. Use this to plan shift start times, breaks, and coverage. The table highlights peak hours and calculates cumulative FTE across the day.

AHT (seconds)

Service level target

Shrinkage (%)

Enter call volume for each 30-minute interval. Click any cell to edit.

Scenario comparison: Model up to 3 staffing scenarios side by side — e.g. current state, optimised state, and growth forecast. Each scenario runs a full Erlang C calculation and the tool highlights the best performer across cost, service level, and occupancy.

Cost modelling: Translates agent headcount into total labour cost, including on-costs (employer NI/taxes, benefits, equipment), recruitment cost, and the cost of turnover. Shows the financial impact of understaffing (overtime, attrition) vs overstaffing (idle pay).

Staffing Inputs

Agents required (from Erlang)

Average annual salary per agent (£ / $)

On-costs — employer taxes, benefits (%)

NI, pension, healthcare, equipment. UK standard ≈ 20–25%

Hours per week (FTE contract)

Turnover & Recruitment

Annual turnover rate (%)

Contact centre industry average: 30–45%

Cost to recruit per agent (£ / $)

Job boards, agency fees, internal HR time. Typical: 1–2× monthly salary

Training cost per new agent (£ / $)

Overtime premium (%)

% above base rate paid for overtime. Standard: 25–50%

Rostering planner: Converts FTE requirements into a weekly shift schedule. Enter required agents per shift, then the tool calculates how many full-time and part-time staff you need across a 7-day rotation, accounting for days off and coverage requirements.

Shift Configuration

Number of shifts per day

Agents required per shift

Operating days per week

Working days per week per agent

Shrinkage (%)

Part-time proportion (%)

% of headcount who work part-time (0.6 FTE)

Industry benchmarks: Standards sourced from SWPP (Society of Workforce Planning Professionals), ICMI (International Customer Management Institute), Call Centre Helper research, and Gartner workforce analytics studies. Enter your actual metrics to compare against industry norms.

Enter Your Metrics

Service level achieved (%)

Average Speed of Answer — ASA (seconds)

Occupancy rate (%)

Shrinkage (%)

Annual turnover (%)

Abandon rate (%)

First call resolution (%)

Cost per contact (£ / $)

Benchmark Comparison

Industry Standard Benchmarks Reference

Sources: SWPP, ICMI, Call Centre Helper, Gartner 2024

Metric	Standard	Good	Best Practice	Watch Below
Service Level	80% in 20s	85% in 20s	90% in 15s	Below 70%
ASA	20–30 seconds	Under 20s	Under 10s	Above 60s
Occupancy	80–85%	75–82%	70–80%	Above 90%
Shrinkage	25–30%	20–25%	Under 20%	Above 35%
Turnover	25–35%	15–25%	Under 15%	Above 45%
Abandon Rate	3–5%	Under 3%	Under 2%	Above 8%
First Call Resolution	70–75%	75–82%	Above 85%	Below 60%
Cost per Contact (£)	£4–£7	£3–£5	Under £3	Above £10