Lot Subdivision Area Helper
Choose one side of a simple convex plane-grid polygon and move a parallel working line inward until the side-adjoining portion reaches the requested area. The cut coordinates, balance area and full calculation trace remain visible for independent review.
Uses only this tool title and its public link. Inputs, results, coordinates and filenames are not included. Sharing starts only when you press the button.
Free advisory field tool — every result is computed in your browser from the inputs you provide and is advisory and unverified, not for survey deliverables. Where a published guideline applies, results only ever read “within guideline” or “exceeds guideline — review”. The full working is shown for every calculation so each step can be re-checked. Registered surveyor confirmation required before reliance.
Parallel cut and resulting portions
A parallel plane-grid working line was calculated for the chosen-side portion. Title boundaries, planning rules, access, easements, services, minimum dimensions and field marking remain outside this calculation.
- Source area (m²)
- 1500
- Requested area (m²)
- 600
- Calculated chosen-side area (m²)
- 600
- Calculated balance area (m²)
- 900
- Area difference (m²)
- 0
- Chosen side
- P1 → P290°00′00.00″ · 50 m
- Perpendicular cut offset (m)
- 12
- Parallel cut
- 90°00′00.00″ · 50 m
| Endpoint | Easting (m) | Northing (m) |
|---|---|---|
| A | 500000 | 6960012 |
| B | 500050 | 6960012 |
| Point | Easting (m) | Northing (m) |
|---|---|---|
| P1 | 500000 | 6960012 |
| P2 | 500000 | 6960000 |
| P3 | 500050 | 6960000 |
| P4 | 500050 | 6960012 |
| Point | Easting (m) | Northing (m) |
|---|---|---|
| P1 | 500000 | 6960012 |
| P2 | 500050 | 6960012 |
| P3 | 500050 | 6960030 |
| P4 | 500000 | 6960030 |
Show the working
- source polygon areatranslated compensated shoelace magnitude1500
- requested chosen-side areaentered target area600
- chosen side lengthhypot(delta E, delta N)50
- inward search extentmaximum perpendicular distance from chosen side30
- parallel cut offsetbisection of clipped-area minus requested area12
- parallel cut lengthdistance between boundary intersections50
- calculated chosen-side areatranslated compensated shoelace magnitude after clipping600
- area differencecalculated chosen-side area - requested area0
- calculated balance areatranslated compensated shoelace magnitude after clipping900
- area balance residualchosen-side area + balance area - source area0
- numeric area envelopebinary64 coordinate spacing and operation bound0.0000514324
Working trace rendered from the same computation as the result above — re-check any step by hand before relying on it.
Prepare a local sheet copy (PDF/CSV)
Prepare the current lot subdivision working sheet directly in this browser. CSV downloads here; PDF opens the print dialog so you can save it. Nothing is submitted to SurveyMarkup.
How to use the lot subdivision calculator
Enter a convex plane-grid boundary, choose the retained side and request an area for a provisional parallel-cut calculation.
Enter the ordered boundary
Paste at least three easting and northing vertices for one simple, strictly convex plane-grid ring in boundary order.
Choose side and area
Select the side adjoining the requested portion and enter a target area greater than zero and smaller than the source area.
Review both provisional portions
Inspect the parallel cut, cut endpoints, requested-area difference, both coordinate rings and the full working before further design review.
Questions about Lot subdivision area helper
What does a lot subdivision calculator in Australia produce?
This lot subdivision calculator places a parallel working line in a simple convex plane-grid polygon and reports two provisional coordinate rings for review in Australia.
Can the helper process a concave boundary?
No. The current calculation is limited to a simple strictly convex ring, with the chosen-side portion adjoining one entered polygon side.
Does the result establish a legal subdivision boundary?
No. Title status, planning requirements, access, easements, services, minimum dimensions, datum, scale and field marking remain outside this area helper.
Safety & scope
SurveyMarkup helps prepare and review working information. Every professional decision remains with the registered surveyor, and original data and final outputs require qualified review.
Assistance only - professional review remains required.