# Built-Up Area Ratio Calculator

> Work out the floor area ratio (FAR or FSI) and ground coverage of a plot, and how much more you could build under the FAR limit you enter.

Category: Real estate · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/built-up-area-ratio-calculator

The built-up area ratio, usually called floor area ratio (FAR) or floor space index (FSI), is the total floor area of all storeys divided by the plot area. Planning rules cap it, so it decides how much you can build.

Also called: Floor area ratio (FAR) calculator, Floor space index (FSI) calculator.

## Inputs
- Plot area (unit sq ft or m²; default 4000)
- Total built-up area (all floors) (unit same unit; default 6000)
- Ground-floor footprint (unit same unit; default 2000)
- Permitted FAR / FSI (default 2)

## Results
- Built-up area ratio (FAR / FSI)
- Ground coverage
- Maximum built-up area at the permitted FAR
- Area still buildable (negative = over the limit)
- Equivalent full floors

## Formula

```
FAR = Total built-up area ÷ Plot area;  Ground coverage = Footprint ÷ Plot area × 100;  Maximum built-up = Permitted FAR × Plot area;  Floors ≈ Built-up ÷ Footprint
```

Where:
- Built-up area: floor area of all storeys, measured as your local rules define it
- Footprint: the ground area covered by the building

## Worked example
1. FAR = 6,000 ÷ 4,000 = 1.5.
2. Ground coverage = 2,000 ÷ 4,000 = 50%.
3. At a permitted FAR of 2, the maximum is 2 × 4,000 = 8,000, leaving 2,000 to build.

**Result:** The building has a FAR of 1.5 and covers half the plot; another 2,000 units of floor area fit within a FAR of 2.

## What the result means

A FAR of 1.5 means the floor area equals one and a half times the plot. If the result is over your permitted limit, the extra area may need approval or a purchased development right, depending on local rules.

## Assumptions and limits
- All areas are in the same unit.
- The permitted FAR is the one you enter; what counts towards it (balconies, stairs, parking) depends on local rules.
- Does not apply setbacks, height limits or premium FSI schemes, which can restrict or extend what you can build.

## Questions

### Is FAR the same as FSI?

Yes. Floor area ratio and floor space index are two names for the same ratio. Some places write it as a percentage (FAR 1.5 = 150%).

### What is the difference between carpet, built-up and super built-up area?

Carpet area is the usable floor inside the walls; built-up adds the walls and balconies; super built-up adds a share of common areas. FAR rules specify which areas count.

## Related calculators
- [Price per Square Foot Calculator](https://calculators.geekmidst.com/calculators/price-per-square-foot-calculator)
- [Construction to Property Value Calculator](https://calculators.geekmidst.com/calculators/construction-to-property-value-calculator)
- [Ratio Calculator](https://calculators.geekmidst.com/calculators/ratio-calculator)
- [Percentage Calculator](https://calculators.geekmidst.com/calculators/percentage-calculator)

_Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials._

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/built-up-area-ratio-calculator