Buildable Area Calculator: How Much Can I Build?

To find how much you can build on a lot, take the plot area, subtract the setbacks to get the buildable envelope, cap the footprint by the lot coverage limit, multiply by the number of floors, and cap the total by the floor area ratio (FAR). Enter the numbers from your local zoning rules and the calculator shows the largest house allowed, which rule limits it, and a top-view diagram.

How the calculator works

  1. Enter the plot Width along the street and depth, in metres or feet.
  2. Add your zoning numbers Setbacks, lot coverage, FAR and floors from your local plan or zoning code.
  3. Read the limit See the largest floor area, the footprint, the rule that limits you and a diagram.

Three numbers that decide your house size

Setbacks
The minimum distance between the building and each boundary. What is left is the buildable envelope.
Lot coverage
The share of the plot the building may cover, measured at ground level.
Floor area ratio (FAR)
Total floor area of all floors divided by the plot area. FAR 0.6 on 500 m² allows 300 m².

Worked example

A 20 × 25 m plot is 500 m². Setbacks of 5 m front and rear and 3 m on each side leave an envelope of 210 m². With 35% lot coverage the footprint is capped at 175 m². Two floors would give 350 m², but a FAR of 60% caps the total at 300 m², or 150 m² per floor.

Questions about building rights on a plot

How do I calculate how much I can build on my lot?

Multiply the plot area by the floor area ratio to get the total floor area allowed. Then check the footprint: the area inside the setbacks, capped by the lot coverage limit, times the number of floors. The smaller of the two is your limit.

What is the difference between FAR and lot coverage?

Lot coverage limits how much ground the building covers. FAR limits the total floor area of all floors together. A plot can allow a small footprint on several floors, or a large footprint on one.

Where do I find the setbacks and FAR for my plot?

In your municipality's zoning code or local plan. Many cities publish a zoning map online, and a zoning or planning information letter from the local authority confirms the rules for a specific plot.

Do basements, balconies and parking count toward FAR?

It depends on the local rules: many plans exclude some areas, such as basements, service areas or open balconies. Enter the rights for the main floor area, and check the exclusions in your plan.

Next step

A planning aid based on the numbers you enter, not a zoning approval. Your local planning authority has the final word.