---
title: "FSI calculator"
method: POST
path: "/api/v1/tools/fsi_calculator"
---

# FSI calculator

`POST /api/v1/tools/fsi_calculator`

## Request

- Base URL: `https://verified.realestate`
- URL: `https://verified.realestate/api/v1/tools/fsi_calculator`
- Auth: HTTP bearer

Free FSI calculator for one rectangular plot in Tamil Nadu under TNCDBR 2019 (the Tamil Nadu Combined Development and Building Rules): the maximum and the achievable FSI, the permissible and the achievable built-up area, floors and height, the front, side and rear setbacks, plot coverage, open space reservation, and the premium FSI the road width allows with its charge as a share of the guideline value. Same engine as Build Scope and the public FSI calculator. Use for "what is the FSI", "how much can I build on my plot", "premium FSI on a 30 feet road", "how many floors on a 40x60 plot". Needs the plot area, frontage, depth and the road width the plot faces; give unit "feet" when the figures are in feet and square feet. Zone flags (cba, ews, aquifer, redhills, crz, tod) change the rules: pass what the user or an earlier zone check said, never guess them. For parking, scenarios and a drawn plan, offer the Build Scope report (paid). Cite the rule each figure comes with. Free.

## Request body

- object
  - `plot_area` number, required: Plot area, in square metres (or square feet when unit is feet)
  - `frontage` number, required: Width of the plot along the road, in metres (or feet)
  - `depth` number, required: Depth of the plot away from the road, in metres (or feet). For an irregular plot, the largest rectangle that fits.
  - `road_width` number, required: Width of the road the plot faces TODAY, in metres (or feet). The rules read the existing width (Rule 29(2)(b)).
  - `road_widening` number: Depth of the plot the planning authority will take for a proposed road widening, in metres (or feet). Optional.
  - `unit` 'metres' | 'feet': metres (sq.m) or feet (sq.ft) for every length and area given. Default metres.
  - `housing_units` integer: Homes planned. More than 16 makes it a large development. Default 8.
  - `commercial_area` number: Commercial floor area planned, in SQ.M whatever the unit. Over 300 sq.m makes it a large development. Default 0.
  - `priority` 'builtup' | 'height' | 'coverage': builtup = the floors that build the most floor area (default); height = the most floors the rules allow, with wider setbacks; coverage = the largest footprint, usually fewer floors.
  - `high_rise` boolean: Plan a high-rise building (over 18.3 m). Needs a 12 m road and room for 7 m setbacks; otherwise the answer falls back to a non high-rise building and says why.
  - `cba` boolean: The plot is in a Continuous Building Area
  - `ews` boolean: The plot is in an Economically Weaker Section area or a natham
  - `aquifer` boolean: The plot is in the aquifer recharge area
  - `redhills` boolean: The plot is in the Redhills lake catchment
  - `crz` 'none' | 'crz1' | 'crz2' | 'crz3': Coastal Regulation Zone category of the plot. Default none.
  - `tod` boolean: Within 500 m of a Metro Rail corridor (premium FSI charge halved)
  - `zones` string[]: The same zone flags as a list, for a form: any of cba, ews, aquifer, redhills, tod.

## Response `200`

The envelope: ok, status, data, credits_charged, balance_after, request_id

## Other responses

- `401`: No valid credential
- `402`: Not enough credits
- `429`: Rate limit

---

[API](https://skmtc.dev/verified/apis/landlens-tool-api.md) · [All operations](https://skmtc.dev/verified/apis/landlens-tool-api/llms.txt) · [OpenAPI document](https://skmtc.dev/verified/apis/landlens-tool-api/revisions/7923c1c24431?raw)