How to estimate a small interior painting job

1. Decide exactly what “paint the room” includes.

A customer may mean walls only. Your estimate may also include a ceiling, trim and two doors. Settle that difference before doing the math.

For this example, the job is one empty, rectangular room with walls already in a condition suitable for the specified repaint. The scope is walls only, one finish color and two finish coats. Floor protection, the preparation identified during inspection, setup and cleanup are included. Ceilings, doors, trim, closets, substantial repairs and full-surface priming are excluded.

If inspection reveals a different surface condition or preparation requirement, revise the scope and costs. The example is a way to organize an estimate, not a specification for treating every wall.

2. Measure the walls, then subtract the openings.

The room has 120 square feet of floor area. That is not the area of the walls. For a rectangular room with four walls at the same height, multiply the perimeter by the height:

This room has one 3 × 7 ft door and two 3 × 4 ft windows. Those openings account for 21 + 24 = 45 square feet. Subtract them because we are not painting the doors or glass:

This is the same measurement approach described by Sherwin-Williams: total the wall areas and subtract doors and windows. Measure the actual openings rather than assuming every door or window is the same size.

A smaller area does not always mean less work. Windows reduce the surface needing paint but create edges to work around. Keep the material calculation separate from the labor estimate. For irregular rooms or different wall heights, measure each wall separately.

3. Turn the wall area into a paint quantity.

Use the coverage and coat requirements for the product you plan to buy. In this example only, assume 350 square feet per gallon per coat. Two coats over 307 square feet require:

If you are buying one-gallon containers, that means two containers before any extra reserve you decide the job needs. Price the containers you must buy, not just the calculated fraction of a gallon.

Coverage changes with the product, surface and application. Sherwin-Williams makes that limitation clear in its paint calculator. Check the label and surface requirements. Primer, additional coats or a reserve beyond the rounded purchase quantity need their own allowance.

4. Count all labor hours, including the small tasks.

Break the job into tasks you can estimate and later compare with the actual time spent. Include loading, travel allocated to the job, protection, preparation, paint application, cleanup and any return visit. A small room still has setup time.

The example allows four total labor hours for setup, protection, the identified preparation and cleanup, plus eight for paint application and the associated work. These 12 hours are assumptions for the calculation, not a production rate or a promise that the job takes that long.

Multiply those hours by your loaded labor cost: the cost of employing the person for that time, including the costs your business assigns to labor. Account for your own labor too. Do not treat it as free because you are the owner.

5. Build the cost total before choosing the price.

Here is the complete assumed cost breakdown. The $30 hourly cost, $55 paint price and other allowances are invented for this worked example. They are not Texas market averages.

Supplier taxes, fees or other job costs must be included where they apply to your business. They are not separately modeled here. If access, repairs or an additional visit changes the work, change the cost sheet before sending a fixed selling price.

6. Choose a price and check what it leaves.

Suppose you want to test a 25% gross margin on this example's direct costs. Divide the cost by one minus the target margin:

At $700, the difference between the selling price and the $525 direct cost is $175. That is 25% of the selling price, before overhead and other expenses. It is not a statement of net profit or a recommended margin for your business. Decide whether the amount left is enough for your actual costs and profit goal.

Adding 25% to the cost gives a different result. A 25% markup produces $656.25: $525 × 1.25. The $131.25 left is 20% of that selling price. Markup and margin use different denominators.

What if preparation takes two hours longer?

At the example's $30 loaded labor cost, two extra hours add $60. Direct costs rise to $585. If the price stays at $700, $115 remains before overhead, a gross margin of about 16.4%. Keeping the same 25% target would require a price of $780.

This is why a note about wall condition belongs in the scope. Once you have given a customer a price, additional time does not automatically authorize an extra charge. Discuss scope changes and the proposed price adjustment before doing additional work.

7. Put the useful details on the customer estimate.

The customer needs the work, selling price and next step. Your internal cost sheet serves a different purpose. Here is sample scope wording to adapt after inspecting the actual job:

Repaint the walls of one 12 × 10 ft room with 8 ft ceilings, in one selected finish color. Includes floor protection, the preparation listed after inspection, two finish coats, setup and cleanup. Excludes ceiling, trim, doors, closet interiors, substantial repairs and full-surface priming. Example selling price: $700, before any applicable separately stated charges.

Add the selected product, the preparation you actually allowed for, access arrangements, timing assumptions, estimate reference and validity period. Explain how the customer can ask questions or request a revision. Keep the version you send with the job record.

Use our contractor estimate checklist for the final review. When it is time to bill, the estimate vs. invoice explanation helps keep proposed work, billing and payments separate.

Questions that come up on small painting jobs

Can I price the job from the room's floor area?

Floor area alone leaves out wall height, openings and the surfaces included. For this 12 × 10 ft room, the floor is 120 square feet while the net wall area is 307. Build the takeoff from the surfaces you will paint.

Should I subtract windows when estimating labor?

The opening reduces paint quantity, but working around its edges still takes time. Use the net area for the paint calculation and assess the detail work separately when estimating hours.

Is $700 the right price for a room in Texas?

It is the result of this example's assumptions. A Texas job needs local supplier quotes, your labor costs, the actual scope and a price that supports your business. Use the method and replace the inputs.

What should I compare after the job?

Compare estimated and actual labor by task, paint purchased and used, other costs and changes in scope. Use those records to improve the assumptions in your next estimate.

About this article

Prepared for the Quote Your Jobs blog. Worked examples use illustrative assumptions, not customer case studies or local market rates. Replace them with the actual scope, supplier information and costs for your job.