TDR calculator
Work out the gap.
Enter a plot area and two FAR figures to see the additional floor area implied. Indicative arithmetic, to frame a conversation — nothing more.
What the site allows without TDR.
The figure you are working towards.
- Plot area
- 12,500 sq ft
- At base FAR 1.75
- 21,875 sq ft
- At permissible FAR 2.5
- 31,250 sq ft
Additional floor area sought
9,375 sq ft
871 sq m
This is not a DRC quantityThe figure above is the additional floor area you would be seeking. How much certificate entitlement that requires, and whether any of it is permissible on your site, is determined by the competent authority under the applicable rules — not by this arithmetic.
The working
There is no secret in it.
Two multiplications and a subtraction. You can check it by hand.
Floor area at a given FARplot area x FAR
Additional floor area sought(plot area x permissible FAR) − (plot area x base FAR)
Worked through in full, with an example, on Understand TDR. Need to convert units first? Use the converter.
Limits
What it does not tell you.
Four things this arithmetic cannot answer, however precise it looks.
- Not a DRC quantityIt gives the additional floor area sought. How much certificate entitlement that requires is set by the authority's rules.
- Not a permissionIt cannot tell you whether additional floor area may be used on your site. Zone, site conditions and the authority decide that.
- Not an eligibility checkIt says nothing about whether a certificate, or your project, qualifies for anything.
- Not a priceNo value, percentage or market price is implied. A reference value is not a confirmed price.
Next step
Turn a figure into a review.
Output is indicative only and must not be relied on for eligibility, valuation, design or approval decisions. Figures require case-specific review with the competent authority and your own advisers. See the calculator disclaimer.