Most cleaning robot proposals die in the same place: not on the floor, not in the pilot, but in a spreadsheet where somebody typed a labour rate nobody agrees with. A cleaning robot ROI case survives finance review only when every line is either observable on your site or quoteable from a supplier. This page gives you that structure — the savings formula, the assumptions to declare up front, the consumables line most proposals forget, and a payback table you can drop your actual quote into.
Nothing here requires believing a vendor’s marketing number. Every input comes from your own rota, your own wages, and your own floor.
The cleaning robot ROI formula: only the hours that actually end
Start by counting what robot cleaning removes from the rota. Not the whole cleaning budget — just the floor-cleaning hours the machine takes over:
Nightly floor hours = area cleaned per night ÷ manual coverage rate × number of passes
Worked example with assumptions declared: an 8,000 m² facility, currently cleaned by two cleaners for three hours each, six nights a week. Manual coverage on foot is roughly 150–200 m² per hour for machine-assisted mopping, so the job is real — call it 12 labour-hours per night. At a fully loaded rate of $18 per hour (wages plus employer costs; range $14–25 in most Western markets), that is about $216 per night, or $67,000 per year of floor-cleaning labour.
Now the honest part: the robot does not eliminate every one of those hours. Someone still empties tanks, checks brushes, and handles the odd intervention — typically 15–30 minutes per shift. Subtract it:
Net nightly saving = nightly floor hours − robot oversight time, × loaded rate
In the example, 12 hours minus half an hour of oversight, at $18, is about $198 per night — roughly $61,500 a year at six nights. That $61,500, not the full $67,000, is the number your boss should see. Finance trusts models that subtract their own weaknesses.
Throughput: why the rated number is half the story
The machine’s rated capacity sets the ceiling. A compact unit like the SC50 is rated around 1,800 m²/h; a large platform like the SC80 around 4,000 m²/h; the waterless SW80A around 1,600 m²/h. Real-world throughput lands well under those figures once the machine slows for corners, returns to dock, and waits out a water refill:
- Plan on 40–60% of rated throughput for mixed floors with obstacles, closer to 60–70% in open bays.
- One pass or two? A visibly soiled floor needs overlapping passes; budget it from the start rather than discovering it in month two.
- Sizing check: if the area ÷ realistic throughput exceeds the available cleaning window, you need either a bigger class or a second machine — no ROI model fixes a sizing error.
This is where the buyer’s checklist earns its keep: machine class first, arithmetic second. A machine too small for the floor produces a payback that never arrives.
The line every proposal forgets: consumables
Here is the pattern most ROI spreadsheets miss in both directions. Opponents of automation inflate consumables to scare the project; vendors omit them entirely. The truth is boring and favourable: consumables are small, predictable and quoteable — which is exactly what a finance reviewer wants.
For one machine on a daily shift, the wear parts are brushes, squeegee blades, filters, dust bags, cloths and casters. Across a year the parts bill for a single machine is typically a few hundred to a low four-figure sum — call it 2–5% of one cleaner’s annual salary, not a second salary. The reason it stays small is discipline: a monthly inspection catches parts worn, not parts failed. The maintenance schedule exists precisely so the consumables line stays a line item instead of becoming downtime.
The strategic point: because wear parts are standard, stockable items — see the spare parts and consumables catalogue — your consumables cost is something you can quote today, not estimate. That puts it on the same footing as the labour number, which is what makes the whole model credible.
Payback: the table you can plug a quote into
Machine price is the one input we will not invent for you — it depends on class, configuration and market, and the price guide explains why no honest single number exists. So take the quote you receive and read the payback off this table:
| Machine quote | Net nightly saving | |||
|---|---|---|---|---|
| $120/night | $160/night | $200/night | $250/night | |
| $20,000 | 14 mo | 10 mo | 8 mo | 7 mo |
| $30,000 | 21 mo | 16 mo | 13 mo | 10 mo |
| $40,000 | 28 mo | 21 mo | 17 mo | 13 mo |
| $50,000 | 35 mo | 26 mo | 21 mo | 17 mo |
(Months = quote ÷ saving, rounded; a $30,000 machine at $200/night returns in ~13 months, and so on.) Three things to add underneath any payback table before presenting it:
- Multi-shift leverage. A machine that runs two shifts a night does not double the savings — but it doubles the floor hours displaced per machine, which changes which row of the table you are in.
- The recruitment line. In most markets the honest comparison is not “cleaner’s wage vs robot” but “vacant cleaner position vs robot”. A night-shift cleaning role that stays unfilled for months is already costing you the full saving figure — the machine is competing with a vacancy, not a person. For many sites this is the single biggest ROI lever, and it is why night-shift-focused sites justify machines that spreadsheet-only models reject.
- Residual value and life. Commercial units are typically budgeted over five-plus years. Payback in 18 months on a five-year asset is a different animal than the same payback on a three-year lease.
The one-page model, assembled
- Area and window: m² per night, cleaning hours available.
- Machine class and realistic throughput (40–60% of rating): does the window close?
- Labour: nightly floor hours × loaded rate, minus 0.5 h oversight = net nightly saving.
- Consumables: quoted parts list for year one (2–5% of one salary).
- Payback: quote ÷ nightly saving, read off the table, then re-state with the vacancy argument if your night role is unfilled.
If the resulting number clears your company’s hurdle rate, the last step is a real quote instead of a table row. Send us the four numbers from step one — area, window, narrowest passage, shift pattern — and we will return a sized configuration with a consumables list you can paste straight into the model. If you want to see it before asking, the warehouse floor cleaning robot quote page lays out the format.