PARCIC.Setback calculator.
See the space inside the lines.
Enter a rectangular lot and four yard assumptions. See the remaining rectangle and its area, with front, rear and side setbacks kept separate.
No signup · Feet or meters · Shareable numeric scenariosDraw your assumed setbacks.
Use a rectangular lot and enter each yard separately. Front is the street-facing edge at the bottom of the diagram.
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A geometric envelope under these assumptions. This is not a proposed building footprint.
Entered lot Remaining rectangle · diagram to scale
- Remaining width × depth
- 45 × 60 ft
- Lot area
- 6,000 sq ft
- Remaining share of lot
- 45%
- Envelope area in square meters
- 250.84 sq m
Have an address?
Find available parcel and mapped zoning evidence. Confirm which rules apply before treating the calculator’s inputs as requirements.
How to calculate a rectangular setback envelope
Use the same length unit for the lot and every setback. This exercise places a front edge along the bottom of the diagram and subtracts each entered yard from its corresponding edge.
Inside width = lot width − left setback − right setback
Inside depth = lot depth − front setback − rear setback
Rectangle area = inside width × inside depth
If either inside dimension is zero or negative, the entered setbacks leave no positive-area rectangle. The diagram is a calculation aid, not a survey or a map of a real parcel.
Worked example: a 60 × 100 ft lot
Assume a 20 ft front setback, 20 ft rear setback, 5 ft left setback and 10 ft right setback. The inside width is 60 − 5 − 10 = 45 ft. The inside depth is 100 − 20 − 20 = 60 ft. The resulting rectangle is 2,700 sq ft.
This area is a geometric envelope under those assumptions. It does not account for lot coverage, required open space, easements, parking, driveway access or an existing building.
| Left / right yards | Inside rectangle | Area |
|---|---|---|
| 5 / 5 ft | 50 × 60 ft | 3,000 sq ft |
| 5 / 10 ft | 45 × 60 ft | 2,700 sq ft |
| 30 / 30 ft | No positive width | 0 sq ft |
Setbacks, lot coverage and FAR are different checks
The setback exercise concerns a ground-level rectangle. A coverage limit may allow a smaller footprint. FAR concerns counted floor area across the building, using the local ordinance’s definitions.
For the same fictional 6,000 sq ft lot, a 40% coverage assumption gives a 2,400 sq ft footprint cap—smaller than the 2,700 sq ft rectangle above. Neither number verifies where a building can go. Compare the area inputs with the free FAR and lot coverage calculator.
Find the actual setback requirements
- Confirm the legal site, survey dimensions and governing municipality.
- Locate the applicable district, overlays and adopted code. Use the zoning code and map directory as a starting point.
- Verify which lot lines count as front, rear and side, including street-facing sides on corner lots.
- Check how the authority measures yards, and whether projections, easements, access or other controls affect the project.
The guide to finding zoning by address explains how to keep a district label separate from a verified development rule.
Common questions
Does this tell me what I can legally build?
No. It subtracts the numbers you enter from a rectangular lot. Permitted use, current zoning, parcel identity and all other requirements still need verification.
Can I use it for a corner or irregular lot?
It models one rectangle with one front edge. It does not infer street orientation, multiple frontages, curved boundaries, slopes or irregular lot lines. Those need a property-specific plan and the governing measurement rules.
Can I compare feet and meters?
Yes. Enter all six lengths in the selected unit. Changing the unit changes how the entered numbers are interpreted; it does not automatically convert your inputs.
Can I share my result?
Open “Share or reset” to copy a link containing the numeric assumptions and unit. It contains no property address or private study data.
Reference and method
Los Angeles City Planning’s regulations overview is an official example of why setback summaries require the underlying code and property-specific review. This calculator applies no Los Angeles rule or any other municipality’s setback values.
The rectangle diagram and arithmetic are PARCIC’s illustrative method. For an actual site, a qualified professional should confirm survey boundaries and applicable measurement rules.
Tool and explanation updated November 7, 2026. Entered values remain unverified assumptions.