Empty Night Shifts Are a Labor Cost You Can Measure

What does an unfilled night shift really cost?

An unfilled night shift seldom appears on a payroll report as a line called empty shift. It appears as floors that were never scrubbed, aisles swept late or not at all, and a day crew that stays past its clock-out to catch up. The cost is real, but it spreads across overtime, idle hours and work that slides into the morning.

The clearest way to price it is to count three things from your records: scheduled hours that went undone, overtime paid to cover those gaps, and day shift time spent on night tasks. Each bucket has a source document you already keep, so the number can be checked by someone outside the building team.

Measure a recurring pattern, not one bad night. Eight weeks of shift records is a sensible starting window, because it shows whether gaps repeat by weekday, by season or by the same staff member being out sick.

Which three buckets should you count?

Start with undone hours. The night task board or close checklist shows what was scheduled, and the gap is whatever was never marked complete. Log the zone, the task and the reason, because a repeated reason points to a staffing problem rather than bad luck.

Overtime counts only when it traces to a specific uncovered task. Overtime worked for an unrelated reason, such as a large freight receipt, stays out of the gap. Spillover is harder to see, because day staff rarely log time against night work. Ask supervisors to tag those tickets for the same eight weeks.

How do you build the worksheet from timesheets?

Export eight weeks of night and day timesheets, then flag each night shift where the task board shows open work. Keep the flag in its own column, separate from logged hours, so a reviewer can see which hours were recorded and which were inferred.

Next, assign each hour a cost from payroll. The Bureau of Labor Statistics put the May 2024 median wage for janitors and building cleaners at $17.27 per hour, and projects about 350,300 openings a year on average over the decade. Use your staff rates in the worksheet. The national median only shows how tight the labor pool is.

Add benefits and payroll taxes only if your finance team already applies them to labor. Do not add a load factor based on a guess. Worksheet totals should match payroll, and any unexplained difference is a finding in its own right.

How should overtime and shift premiums be priced?

Federal rules require covered employees to receive at least 1.5 times their regular rate for hours over 40 in a workweek, according to the U.S. Department of Labor. The overtime figure is built on the regular rate, which includes a shift differential where one applies, and that rate cannot be set by agreement.

Night differentials are common, although the survey data is old. A 2010 Culpepper survey, republished by SHRM, found 92 percent of companies pay shift differentials to hourly employees. An ERC Northeast Ohio survey from 2011 found 66 percent of employers offer them for weekday second shifts and 55 percent for weekday third shifts. Treat these as background, and take the actual premium from your pay records.

Do not price one hour twice. If overtime covered an undone task, count that hour once, as overtime, and leave it out of the undone hours line. Otherwise the worksheet inflates the gap, and a reviewer will catch it.

The worksheet reduces to one formula, applied to each of the eight weeks.

• Gap cost = undone hours at your night regular rate, plus overtime hours at 1.5 times the regular rate, plus spillover hours at the day rate
• Repeat the calculation for each week, then scale to a longer period only if the pattern repeats across seasons

How do you compare the gap with a robot lease?

Set the measured gap beside a robot plan built for the same zones and hours. The comparison only holds if the robot covers the work the empty shift left undone, so start with the zones on your task board, not the whole building.

Service Robot Co. leases robots only, through financing on a three year lease, with one fixed lease payment quoted after a site assessment. We select robots across manufacturers, deploy and integrate them, train your staff, and service every unit through a nationwide US engineer network, so one vendor covers the lifecycle. The site assessment maps the zones and hours, and the quote is the figure you measure against.

Read what the quote covers in writing. Ask whether repairs, dispatch and software updates are included, and what happens when a unit goes offline during a night pass. A floor robot handles scheduled passes, but spills, blocked aisles and alarms still need a person on the night board.

What do the industry numbers show, and where do they stop?

According to the International Federation of Robotics, as reported in press coverage of its 2026 report, professional service robot shipments rose 24 percent to almost 250,000 units in 2025. Professional cleaning ranks third, with floor cleaning as its main application. Those figures came from search snippets rather than the full report, so quote the headline only.

The IFR also says its service robot figures come from a supplier sample and are not projected to the whole market, and that figures should not be compared across World Robotics editions. Rising shipments show peer sites are adopting. They do not show whether your night floor will pay back, and only your worksheet can answer that.

Where should a first measurement start?

No U.S. figure was found for overnight floor care vacancy rates or for the overtime cost of covering gaps, so the number has to come from your records. Choose one shift pattern in one building, run the worksheet for eight weeks, and write down a go or stop threshold before any quote arrives.

Once the measured gap is written down, a pilot on a single zone becomes a test of that same number rather than a leap of faith. Compare the two figures over the same span, and let the result decide the next step.