Staffing calculator

Estimate how many employees you need to cover your opening hours, with a buffer for time off and absence.

In shortPeople needed = (hours open per day × people on duty × days open per week) ÷ average weekly hours per employee, then increased by your buffer for vacation, sickness and turnover.

Who uses itStore, site and shift managers
WhenOpening a location or changing opening hours
You needHours open, people on duty, days open, average hours
ResultHeadcount needed, with and without a buffer

Fill in your numbers

How the math works

Shift-hours per week = hours open × people on duty × days open.

Employees = shift-hours ÷ average weekly hours per employee.

With buffer = employees × (1 + buffer %), rounded up.

See it with numbers

A convenience store is open 12 hours a day, 7 days a week, with 3 people on duty: 252 shift-hours a week. With employees averaging 32 hours, that is 7.9 people, and 9 with a 12% buffer.

When to check your staffing

Use it when you open a location, extend hours or see constant overtime. It gives a starting point; build the actual schedule from demand by hour.

The buffer covers planned and unplanned absence. Use your own absenteeism and leave figures if you have them.

Another staffing example

A physical therapy clinic is open 10 hours a day, 5 days a week, with 2 therapy aides on the floor at all times: 100 shift-hours a week. Aides average 36 hours, so the clinic needs 2.8 aides before buffer. With a 15% buffer for vacation and sick days the need is about 3.19, which rounds up to 4 aides to hire.

Making sense of the staffing number

Employees before buffer is the bare minimum to fill every shift if nobody is ever out. The hire figure rounds up any fraction, so a result like 3.19 might be better covered by 3 people plus a part-timer than by 4 full schedules. Average weekly hours must reflect what people actually work, because a lower average quickly raises the number of people needed for the same coverage.

Frequent staffing mistakes

Planning for the same staffing level all day. Count peak and quiet hours separately or you will be short at rush and idle at slow times.
Using a 40-hour average when most staff are part-time. Use the real average of your team.
Forgetting opening and closing tasks. Add the time before doors open and after they close to hours open.

Adjusting the staffing for your team

Convenience storesRun overnight hours separately, since one person on duty at night may need a safety rule of two.

Call centersUse this for a rough headcount, then refine by call volume per half hour.

Pro tipPlan for the week you hope to grow into, not the week you have. Hiring takes time and a buffer covers the gap.

Frequently asked questions

Does this build a schedule?

No. It estimates headcount; the schedule follows demand by hour.

What buffer should I use?

Use your own leave and absence data; many businesses use 10 to 15%.

What if demand varies by hour?

Calculate busy and quiet periods separately.

Should managers be counted?

Only if they cover the same positions.

How do I plan for a role that needs a license?

Run it as its own calculation, such as pharmacist or hygienist coverage, because a general buffer does not help if the only licensed person on shift calls out. Each licensed role needs its own backup count.

Why is the hire figure rounded up?

You cannot hire 3.2 people, and rounding down leaves shifts uncovered. If the result is just above a whole number, extra hours from existing part-timers may cover the fraction more cheaply than another hire.

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General information and an estimate only. It is not legal, payroll, tax or financial advice. Rules vary by state and city. Check important results with a qualified professional.