Calculator
Example Data Table
| Pattern Diameter | Spacing | Overlap | Effective Swath | Passes (Width 3 m) |
|---|---|---|---|---|
| 1.20 m | 0.60 m | 50% | 0.60 m | 5 |
| 1.00 m | 0.70 m | 30% | 0.70 m | 5 |
| 1.50 m | 0.45 m | 70% | 0.45 m | 7 |
Formula Used
- Diameter from height and angle (optional):
D = 2 × H × tan(θ/2) - Recommended spacing from target overlap:
S = D × (1 − O)whereOis overlap as a fraction - Overlap from spacing:
O% = (1 − S/D) × 100 - Overlapped band:
B = max(D − S, 0) - Passes across width:
passes = ceil(width / S) - Application rate (when flow and speed are provided):
L/m² = (flow_L_min / speed_m_min) / S - Total volume:
V = (L/m²) × area
How to Use This Calculator
- Pick your length and volume units at the top.
- Choose a mode: spacing from overlap, or overlap from spacing.
- Enter a measured pattern diameter, or enable height + angle estimation.
- Add target overlap or measured spacing, depending on the mode.
- Optional: enter bed width and length for passes and area.
- Optional: add flow rate and walking speed for volume and time estimates.
- Press Submit to show results above the form, then export.
Professional Notes
Why overlap matters in garden spraying
Uniform coverage depends on how each pass blends with the next. If spacing is too wide, stripes appear and pests survive. If overlap is excessive, foliage stays wet longer and product is wasted. A practical target is 30–60% overlap, adjusted for wind, canopy density, and nozzle type. Test on cardboard; aim for even droplets across the full band width.
Inputs that change the spray footprint
Pattern diameter can be measured on pavement or estimated from nozzle height and spray angle. Height increases swath but also drift risk. Angle widens coverage but may thin the edge pattern. Record units, keep pressure consistent, and re-check whenever you change tips, filters, or wand extensions. Keep the nozzle centered and maintain constant height above target plants.
Spacing and overlap calculations you can trust
The calculator converts all values to a single unit, then computes recommended spacing as diameter × (1 − overlap). When you enter a real spacing, it reverses the relationship to find actual overlap. It also reports the overlapped band, effective swath, and passes needed across a bed or lawn. If you provide bed width and length, it estimates total path length for a simple back-and-forth pattern. It warns when spacing exceeds diameter and overlap turns negative after conversion.
Planning volume and time for safer mixing
With a flow rate and walking speed, the tool estimates application rate per area using effective swath. Multiply by treated area to get total volume, then compare with your tank size to plan refills. A time estimate comes from total path length and speed, helping you avoid rushing. Slower speeds usually improve coverage and reduce bounce.
Using results for consistent, repeatable work
Start with a small test plot, spray at your normal pace, and verify coverage. If edges look dry, increase overlap or reduce speed slightly. If runoff occurs, reduce overlap, lower pressure, or choose a different nozzle. Save CSV or PDF outputs as a season log for calibration and repeatability.
FAQs
1) What overlap percentage should I start with?
For many garden spot-sprays, start around 40–60%. Dense canopies or uneven patterns often need more overlap, while open ground may need less. Always verify with a quick coverage test.
2) Why does the calculator show negative overlap?
Negative overlap means your spacing is wider than the wet pattern diameter, so passes do not touch. This typically causes striping. Reduce spacing or increase the nozzle height or angle to widen the pattern.
3) Is the height-and-angle diameter estimate accurate?
It is a helpful approximation for flat-fan patterns, but real droplets and pressure change the edges. Use it to get close, then confirm by measuring the wet band on a test surface.
4) How do I measure flow rate for my sprayer?
Collect output for one minute at your normal pressure and count the volume. Repeat twice and average. Use the same nozzle, filter, and battery or pump setting you will use in the garden.
5) Why does speed affect application rate?
At a fixed flow, walking faster spreads the liquid over more ground each minute, reducing application per area. Slowing down increases application per area, which can cause runoff if the surface saturates.
6) When should I re-check my calibration?
Re-check after changing tips, cleaning filters, adjusting pressure, or switching products with different viscosity. Seasonal checks are also useful, because wear and buildup gradually change flow and pattern shape.