Calculator Inputs
Use the fields below to estimate paint quantity, time, waste, and cost for airless sprayer work on building surfaces.
Plotly Graph
This chart compares theoretical volume, required volume, waste allowance, and recommended ordered volume.
Example Data Table
| Item | Example Value |
|---|---|
| Surface Type | Interior Walls |
| Total Surface Area | 180 m² |
| Excluded Openings | 20 m² |
| Coats | 2 |
| Coverage Rate | 9.0 m²/L |
| Transfer Efficiency | 75% |
| Overspray Loss | 8% |
| Surface Absorption | 5% |
| Contingency | 5% |
| Sprayer Flow Rate | 1.10 L/min |
| Productivity Efficiency | 80% |
| Setup and Cleanup | 40 minutes |
| Paint Cost per Liter | $8.50 |
| Hourly Labor Rate | $20.00 |
| Estimated Required Paint | 55.94 L |
| Estimated Total Cost | $509.98 |
Formula Used
This calculator combines coverage, spraying losses, surface absorption, contingency, flow rate, and labor assumptions to estimate paint demand for airless sprayer work.
- Net Spray Area = Total Surface Area − Excluded Openings
- Coated Area = Net Spray Area × Number of Coats
- Theoretical Paint = Coated Area ÷ Coverage Rate
- Loss Multiplier = 1 + Overspray + Surface Absorption + Contingency
- Required Paint = Theoretical Paint × Loss Multiplier ÷ Transfer Efficiency
- Waste and Allowance = Required Paint − Theoretical Paint
- Pure Spray Time = Required Paint ÷ Flow Rate
- Total Site Time = Pure Spray Time ÷ Productivity Efficiency + Setup and Cleanup
- Material Cost = Required Paint × Paint Cost per Liter
- Labor Cost = Total Site Time in Hours × Hourly Labor Rate
- Total Cost = Material Cost + Labor Cost
Percent entries are internally converted to decimals before calculation. This helps the estimator model real-world waste, slower movement, and ordering margin.
How to Use This Calculator
- Choose the surface type that best matches the construction task.
- Enter the total spray area, then subtract windows, doors, or other excluded openings.
- Set the number of coats and the paint coverage supplied by the coating manufacturer.
- Add realistic percentages for transfer efficiency, overspray, absorption, and contingency.
- Enter the sprayer flow rate, productivity efficiency, setup time, paint price, and labor rate.
- Press the calculate button to show results above the form, export them, and review the graph.
Frequently Asked Questions
1. What does transfer efficiency mean?
Transfer efficiency is the percentage of paint that actually lands on the surface. Lower efficiency means more loss in the air, on masking, and during movement.
2. Why should I subtract openings?
Doors, windows, and large gaps are not sprayed the same way as wall fields. Removing them keeps paint estimates tighter and reduces over-ordering.
3. Why is required paint higher than theoretical paint?
Theoretical paint assumes perfect transfer and zero waste. Real jobs lose paint through overspray, porous surfaces, touch-ups, and leftover material in hoses and filters.
4. Can I use this for primer and finish coats?
Yes. Enter the correct coverage rate and loss assumptions for the product you are spraying. Primers and textured coatings often need more material.
5. What flow rate should I enter?
Use the rated sprayer output in liters per minute from the machine specification sheet. If you use a smaller tip, your actual output may be slightly lower.
6. Why is total site time longer than pure spray time?
Pure spray time only reflects liquid output. Total site time adds efficiency losses from repositioning, masking, checking finish quality, and cleanup.
7. Should I always add contingency?
A small contingency helps protect the estimate from touch-ups, color changes, hose residue, or small measurement errors. Many contractors use 3% to 10%.
8. Can I use square feet instead of square meters?
Yes, but convert first. Multiply square feet by 0.092903 to get square meters, then enter the converted area into the calculator.