Preliminary Estimate in Interior design on thumb Rule


According to a layman, dreaming about a space and designing it, are the most important initial steps while converting your imagination into reality. But in real, the most important step is to figure out the project’s budget and costing.

Everything depends on the money in the interior design industry, where various agencies work together using a variety of materials to complete a project. You can complete the project successfully only after you have understood the client’s requirements and budget, and an estimate according to their planned budget.

For calculating an estimate of the project, it is necessary to know the market rates of products and labour.

We will go step-by-step to understand the calculations of the project cost.

Before that, we will learn about a certain type of projects in terms of estimation and costing.

Type of projects:

  1. Standard Project:
    All the rules of designing are followed.
    Good quality of products are used.
    There is no compromise in the strength of the material or labour.
    Budget is controlled in terms of the expensive materials.
  2. Premium Project:
    Best quality materials are used.
    Flexibility of using premium products.
    Good opportunity in creating and adding more comfort.
  3. Luxury Project:
    Use of luxurious customized products.
    No limit on budget.
    The project will be exactly what the client has in mind without any compromises.

You cannot blindly be dependent on the above-mentioned types of the projects. You have to be aware of the client’s style, choices, attitude, perspectives and budget, and then decide what type of project will be the best for the client.

Discuss and finalize with the client as to which one is most appropriate for them. The type of project is designed and finalized on the basis of the project’s cost. Remember, the client is approaching other interior designers as well. Make sure they are going to work with you, and then only start preparing the design and costing of the project.

Types of estimates:

  1. Estimate on thumb rule: This type of estimate is also known as instant estimate. It gives you a rough and nearest estimate of the project. Thumb rule estimate depends on the current market rates of the area of the project, or based on the project that the designer has completed recently.
    No paper work is required.
    No need to work out on the estimate.


For example;

A 3BHK flat has 1700 sqft area.

Current market rate of the project is Rs. 1500/sqft.

To calculate a rough estimate, you just have to multiply the square feet area by the current market rate of the project.

Estimate = 1700 sqft X Rs. 1500 = Rs. 25,50,000/-


If the market rate is, say, Rs. 2000/sqft,

Then, estimate = 1700 sqft X Rs. 2000 = Rs. 34,00,000/-


Thumb rule also works as per the number of rooms.

For example;

3BHK will cost around Rs. 25,00,000/- for a standard project.

And, 3BHK will cost around Rs. 35,00,000/- for a premium project.


This method is used only to give a rough idea of the project’s cost. This will help the client to decide what type of project to choose based on their affordable budget.

It will also help the client to finalize the Interior Designer with their charges and fees.

While the execution of the project, you cannot rely on the estimate amount. For the accurate costing, you will have to work out on the detailed estimate.


  1. Preliminary estimate: Preliminary estimate is more accurate than the thumb rule estimate. It is calculated after the 2D space defining layout plan is finalized.
    At this stage, we are aware of the products we are going to use by the help of the 2D plan. We have the quantity and current market rates of the products.

    For example;
    If we require 2 three-seater sofas of 6’ long. The market rate of a sofa is Rs. 3000/rft.
    So, the cost of the sofa = 6 rft X 2 nos. X Rs. 3000 = Rs. 24,000/-

    Similarly, if the market rate is Rs. 4500/rft.
    Then, the cost of the sofa = 6 rft X 2 nos. X Rs. 4500 = Rs. 54,000/-

  2. Detailed Estimate: A detailed estimate is calculated after the design and materials are finalized. At this stage, we have finalized the design, quantity, quality, applicable materials with their prices, labour rates, and other applicable charges for the project.


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