Floor Area Ratio Calculator

Assess Site Density with More Confidence

A Floor Area Ratio calculator helps you test development intensity early, before a concept gets too far down the road. If you're reviewing a potential site, comparing options, or checking whether a massing idea is realistic, seeing gross floor area and site utilization in one place can save time.

Built for Early Feasibility Work

This tool is designed for developers, planners, and architects who need a clean, technical way to measure density potential. You can calculate gross floor area from a building footprint and number of floors, or use direct floor area inputs when your building layout is less uniform. That flexibility makes it useful for both quick studies and more detailed planning scenarios.

FAR, GFA, and Remaining Capacity

Once the numbers are entered, the tool calculates the Floor Area Ratio and, if needed, compares it with a zoning maximum. That means you can quickly see allowable gross floor area, unused development potential, and how much of the permitted density has already been used. For anyone evaluating site yield, a reliable FAR calculator is one of the simplest ways to bring clarity to the first round of decision-making.

FAQs

What does floor area ratio actually tell me?

Floor area ratio compares a building’s total gross floor area to the size of the lot it sits on. It’s a quick way to understand development intensity on a site. For example, a FAR of 2.00 means the total building area is twice the lot area. That makes it useful in early feasibility work, massing studies, and zoning checks before you get into more detailed design.

What’s the difference between Simple mode and Advanced mode?

Simple mode is best when you’re working from a typical floor plate and a known number of above-grade storeys. The calculator multiplies the building footprint by the number of floors to estimate gross floor area. Advanced mode is more flexible. You can enter a total gross floor area directly or list individual floor areas if each level is different, which is often the case in mixed-use or stepped buildings.

Does this tool confirm zoning compliance?

No. It helps you compare your calculated floor area ratio against a zoning maximum FAR if you enter one, but it does not replace a formal zoning review. Municipal definitions of gross floor area, exclusions, below-grade areas, mechanical spaces, and bonus density rules can vary. Use the result as a strong preliminary check, then confirm the details against the applicable bylaw and project conditions.