Carpet Area Calculator: Carpet, Built-Up and Super Built-Up

What it calculates

Enter any one of the three areas and the converter gives the other two, with:

• the carpet area you can actually fit out and furnish;
• the built-up area, which adds the walls;
• the super built-up area, which adds a share of the common areas;
• the efficiency, carpet area as a percentage of super built-up area;
• each area in square metres;
• optionally, what a rent quoted on super built-up area comes to on carpet area.

Inputs

The area you know is whichever figure the landlord or broker has given you. Leasing proposals usually quote super built-up area.

Area is that figure, in square feet.

Loading is the share of common area charged on top of carpet area, as a percentage of carpet area. Ask the landlord for it, or work it out from a floor's carpet and super built-up figures.

Rent quoted on super built-up is optional. Enter the monthly rent for each square foot of super built-up area to see the equivalent on carpet area.

The wall allowance in the assumptions panel sets how much larger built-up area is than carpet area.

Method

The converter uses the same loading definition as our glossary page on carpet and built-up area:

• Super built-up area = carpet area × (1 + loading).
• Built-up area = carpet area × (1 + wall allowance).
• Efficiency = carpet area ÷ super built-up area.
• Rent on carpet area = rent on super built-up area × (1 + loading).

When you enter super built-up or built-up area, the converter first works back to carpet area by dividing by the matching factor, then works forward to the others.

Assumptions

The wall allowance only affects the built-up figure. Built-up area is rarely used in office leasing, but it appears in some sale documents and older agreements, so the converter shows it for completeness.

Limitations

• Loading is not standard. Definitions differ between landlords, and the same building can quote different loading on different floors. Use the figure from your own lease or proposal.
• Carpet area under RERA is defined for sale of registered projects. RERA 2016 Section 2(k) gives the statutory definition: the net usable floor area within the walls, excluding external walls, service shafts, balconies and verandas, but including internal partition walls. A commercial lease uses whatever definition the lease itself sets out.
• Usable is not the same as efficient. Carpet area includes awkward corners, column zones and deep floor areas far from windows. A floor with the same carpet area can hold more or fewer desks depending on its shape.
• Measured area can differ from the stated area. If the figure matters to the rent, ask for a measurement survey.

Worked example

A broker quotes an office floor of 10,000 sq ft super built-up. The landlord confirms 30% loading. Using a 10% wall allowance:

Only 7,692 sq ft is available for desks, cabins and meeting rooms. At the 93 sq ft of carpet for each person in the office space planner's worked example, that holds a team of about 80, not the 107 that the same density would suggest if it were applied to the 10,000 sq ft headline.

If the rent is quoted at a given figure for each sq ft of super built-up area, the rent for each sq ft of carpet area is 1.3 times that figure, 30% higher than it first appears.

How engineers use it

Designers and project managers work in carpet area throughout: the space plan, the workstation count, the fit-out quantities and the cooling load all follow the area that is actually fitted out. Converting the landlord's figure to carpet area is usually the first calculation on any new office project, before a test fit is drawn.

When a professional design must replace it

Use the converter to compare buildings on the area you can actually use and to understand what a rent quote means. Before you sign, get the carpet area for the specific floor in writing, check how the lease defines each area, and have a designer test fit the floor so you know the area works for your team, not just that it adds up.