Inputs
Enter gross site data, then refine deductions and lot assumptions.
Formula Used
The calculator estimates a first-pass yield using net developable area and a lot-sizing assumption. It does not replace a survey, zoning review, or engineered layout.
| Step | Expression | Meaning |
|---|---|---|
| 1 | Road Area = Gross × Road% | Land dedicated to streets and ROW. |
| 2 | Open Space = Gross × Open% | Reserved parks or required set-aside. |
| 3 | Constraints = Gross × Constraint% | Unbuildable buffers, floodway, slopes. |
| 4 | Pre-Net = Gross − (Road + Open + Easements + Constraints) | Remaining area before layout efficiency. |
| 5 | Net = Pre-Net × Efficiency% | Adjusted for design friction and remnants. |
| 6 | Lots ≈ Net ÷ Lot Size | Rounded per your selected rule. |
Tip: If you already model streets elsewhere, reduce Road% and lower Efficiency%.
How to Use This Calculator
- Pick your area unit, then enter the gross site area.
- Add expected deductions for streets, open space, easements, and constraints.
- Set an efficiency factor to reflect layout complexity.
- Choose a single average lot size, or enable the lot mix toggle.
- Press calculate to view yield and densities above the form.
- Use the export buttons to share results with your team.
Example Data Table
Sample scenario to illustrate inputs and typical outputs.
| Scenario | Gross Area | Road% | Open% | Easements | Constraints% | Efficiency% | Lot Size | Estimated Lots |
|---|---|---|---|---|---|---|---|---|
| Base case | 60,000 m² | 18% | 8% | 1,200 m² | 5% | 92% | 240 m² | ~172 |
| Higher constraints | 60,000 m² | 18% | 8% | 1,200 m² | 12% | 92% | 240 m² | ~156 |
| Smaller lots | 60,000 m² | 18% | 8% | 1,200 m² | 5% | 92% | 200 m² | ~206 |
Results vary by code, frontage, depth, and road geometry.
Early feasibility yield targets
This calculator supports rapid land planning by translating gross tract area into a practical lot yield. It highlights how right-of-way dedication, open space reserves, easements, and constrained land reduce the area available for saleable lots. For concept studies, teams often test three target ranges: a conservative case, a base case, and an aggressive case.
Net developable area and deductions
Deductions are applied in a clear sequence. Percentage items (roads, open space, constraints) scale with site size, while fixed easement area stays constant. The tool then applies an efficiency factor to reflect irregular boundaries, leftover fragments, and alignment compromises. Lower efficiency is appropriate when the site has steep grades, curving streets, or multiple access points.
Lot sizing strategy and mix modeling
In single-size mode, the estimated lots equal net developable area divided by typical lot size, then rounded to your chosen rule. When lot mix is enabled, the net area is allocated across three lot types by share. Each type yield is calculated separately, making it easier to test market-driven product blends, such as starter, mid-range, and premium lots.
Density reporting for planning communication
The summary reports both gross and net density. Gross density relates to overall entitlement and land use discussions, while net density focuses on the portion that can realistically carry lots. Reporting lots per hectare and per acre supports collaboration across international and regional teams. Use density trends to compare alternative layouts quickly.
Export-ready documentation and review
Export functions generate a compact CSV for spreadsheets and a simple PDF summary for approvals, workshops, and consultant reviews. Record assumptions in the notes field so the output is self-explanatory. For due diligence, validate inputs against zoning standards, frontage rules, stormwater needs, and required public improvements. Treat this as a screening tool before investing in full engineering. When refining, replace assumptions with surveyed areas, align road percentages to adopted sections, and adjust efficiency after sketching a block plan. Re-run scenarios to confirm sensitivity and identify key drivers.
FAQs
1) What does “efficiency factor” represent?
It reduces pre-net area to reflect real layout friction, including curved streets, odd remnants, block geometry, and design compromises. Use lower values for complex sites and higher values for regular grids.
2) Should roads be captured in Road% or Efficiency%?
Put planned right-of-way and streets in Road%. Use Efficiency% for smaller losses that appear after sketching, such as corner fragments and unusable leftover slivers. Avoid double counting the same loss.
3) How do I handle setbacks, frontage, or minimum dimensions?
This tool works by area, so dimensional rules should be reflected in your lot size assumption or by lowering the efficiency factor. For detailed compliance, verify with zoning tables and a concept layout.
4) What is the difference between gross and net density?
Gross density uses the entire tract area and is useful for entitlement discussions. Net density uses the net developable area and better reflects the portion that can actually carry lots.
5) How does lot mix mode calculate yields?
Net developable area is split into three shares (A, B, C). Each share is divided by its typical lot size and rounded down to whole lots. The total yield is the sum of the three results.
6) Why can my yield look high compared with a real plan?
Early inputs may miss stormwater facilities, grading limits, access constraints, or required public improvements. Reduce efficiency, increase deductions, or add easement area as details become known, then re-run scenarios.