Can Your Staffing Hit the Response Target?
A first-response target is only achievable if the hours arriving in the inbox each day fit inside the hours people have to work on it. This calculator compares the two, shows the gap in emails per target window, and models what an AI triage layer removes.
Model one shared inbox at a time: support, sales, accounts or admin. Use a typical weekday, not your quietest one.
Shared Inbox SLA Calculator
Handling work versus staffed hours, and the gap against your first-response target.
A typical weekday, counting only messages that need handling.
Reading, checking, deciding and replying, averaged over a real sample.
Actual hours on the inbox, not hours at work.
The clock hours someone is actively covering it.
Above 100% the backlog grows every day and the target is structurally out of reach.
An estimate from the figures you entered. Mail is assumed to arrive evenly across the covered hours and the yearly figure assumes 250 working days. Spikes, interruptions and out-of-hours arrivals make the real breach count higher than shown. Messages needing judgement should stay with a person whatever the automation share.
Reading the Result
The headline figure is inbox load: the handling work arriving each day as a share of the hours staffed to handle it. Above 100 per cent, the target is not reachable with the current roster no matter how hard people work.
Load above 100 per cent means a growing backlog
If handling hours exceed staffed hours, the difference carries over to the next day. Those emails wait at least overnight, so any target measured in hours is missed for them. The daily shortfall output shows how much work is carried forward each day.
The target window shows the gap in emails, not hours
The calculator works out how many emails arrive in one target window and how many your staffing can clear in the same window. The difference is the number of emails per window that will breach the target for structural reasons, before spikes and interruptions are counted.
Triage removes work before a person opens the message
The automation share is the portion of handling time you believe can be removed by classification, routing, drafting and auto-acknowledgement. The result shows the hours removed per day and per year, and what the load becomes afterwards.
How the Figure Is Built
Five steps using only your inputs and one stated assumption about working days.
Daily handling hours
Emails per day multiplied by minutes per email, divided by sixty. This is the work arriving each day.
Staffed hours and load
People on the inbox multiplied by hours each spends on it. Load is handling hours divided by staffed hours, shown as a percentage.
Emails per target window
Emails per day divided by the hours the inbox is covered, multiplied by the target in hours. Assumes mail arrives evenly across covered hours.
Emails clearable per window
Staffed hours divided by covered hours gives the people-hours available per clock hour. Multiplied by sixty over minutes per email, then by the target, gives clearable emails per window.
What Usually Breaks a Shared Inbox Target
Four causes that show up in the numbers once you look at load and window capacity rather than at effort.
Everyone reads, nobody is rostered
Three people each glancing at the inbox between other tasks is not three people on the inbox. Hours each spends on it should be the real figure, which is often well under an hour a day per person. When that is entered honestly, many inboxes turn out to be staffed at a fraction of what the volume needs.
- Enter actual hours on the inbox, not hours at work
- Rostered blocks beat constant partial attention
- Assignment on arrival stops several people reading the same mail
- Interruptions add a cost this calculator does not include
Mail arrives outside covered hours
A target of two hours cannot be met for a message that arrives at 7pm if nobody looks until 9am. The covered-hours input sets how many clock hours a day the inbox is watched. Anything outside that window waits until coverage resumes, whatever the load figure says.
- Count only hours someone is actually watching the inbox
- Out-of-hours mail needs at least an automatic acknowledgement
- Set a separate target for out-of-hours arrivals
- Triage can classify and route overnight so mornings start sorted
Minutes per email is underestimated
Handling time should include reading, looking things up, deciding, replying and any internal follow-up. Timed properly, routine messages often take several minutes and complex ones considerably longer. An average taken from a real sample is the single biggest improvement you can make to the accuracy of this tool.
- Time twenty consecutive emails and average the result
- Include the internal check with a colleague, not just the reply
- Split by category if support and sales share one inbox
- Re-time after any change to tools or process
Backlog age is never measured
A team can be replying quickly to new mail while a backlog of older messages ages unnoticed. The daily shortfall output is the rate at which that backlog grows. If it is above zero, the oldest unanswered message gets older every day until volume drops or staffing rises.
- Report the age of the oldest open message, not just average response
- A shortfall above zero means the target is missed for someone every day
- Clearing the backlog needs extra hours, not just better process
- Triage on the backlog itself finds what can be closed without a reply
Next Steps
AI Email Triage
How classification, routing and drafting take work out of a shared inbox before people open it.
See how it works →Inbox Overload Scorecard
Twelve questions that locate the process gap behind a load figure above 100 per cent.
Score your inbox →Email Time Cost Calculator
Put a dollar figure on the handling hours this calculator found.
Cost the hours →Frequently Asked Questions
It depends on what the inbox is for. A sales or enquiry inbox competing for work usually needs a target measured in an hour or two during business hours, because the enquirer is comparing providers. A support inbox can often work to same business day for routine matters with a faster path for anything urgent. An accounts inbox can usually operate to one or two business days. Set a target per inbox, enter it here, and see whether the staffing supports it before publishing it to customers.
Because a load above 100 per cent means more work arrives each day than the team can clear, so a backlog grows regardless of the target. Any target expressed in hours is missed for the messages carried to the next day. Below 100 per cent the target becomes a question of how evenly mail arrives and how quickly the inbox is checked, which the window outputs cover. Fix load first, then tune for the target.
No. It assumes mail arrives evenly across the covered hours, which is a simplification. Most inboxes have a morning peak and quieter afternoons, and campaign days or an outage can multiply volume for a few hours. Treat the window outputs as the best case for an even day. If your peak hour carries a large share of the daily total, the real breach count is higher than shown.
The calculator does not supply one, because it depends on the mix in your inbox. Classification and routing apply to nearly every message. Drafted replies apply to the recurring questions with an approved answer. Automatic acknowledgement applies to out-of-hours arrivals. Messages that need judgement, negotiation or complaint handling should not be automated at all. Estimate what share of your handling minutes falls in the first three groups and enter that. Lower is safer.
Run both scenarios in the tool. Add a person and see what the load becomes, then instead set an automation share and compare. Hiring adds capacity to every kind of message, including the ones that need a person. Automation removes the routine share only, but it also works outside covered hours and does not take leave. Many teams find that triage alone brings load under 100 per cent, and that the hiring decision is then about growth rather than survival.
No. The calculation runs in your browser and nothing is sent anywhere. Your slider positions are saved in your own browser storage so they are still there if you return, and the reset button clears them. No email content, names or customer details are requested, only counts, minutes and hours.
Load Over 100 Per Cent?
Send us the daily volume and the categories your shared inbox receives. We will tell you what share triage can take out, and whether that gets the target within reach before you roster more people.