Excel for contractors and the trades

Q: How do I calculate square footage in Excel?

Multiply length by width in feet: =B2*C2. For several rooms, =SUMPRODUCT(B2:B4,C2:C4) adds every room in one formula. For wall area, use the perimeter times the height, 2*(length+width)*height, and subtract doors and windows.

Q: How do I round up to whole sheets, boxes or gallons?

Use ROUNDUP with 0 decimal places: =ROUNDUP(1080.8/32,0) returns 34. ROUND goes to the nearest whole number and can round down, which leaves you short on site.

For general contractors, remodelers, electricians, plumbers, painters and anyone who prices jobs and then has to hit the number. Excel handles the takeoff math (square footage, sheets, boxes and gallons in whole units), the quote with your markup, and the job cost report that tells you mid-job whether you are still making money. The examples below use one real-looking job sheet: three rooms of drywall and the cost lines for the job.

General contractors and remodelers
Electricians, plumbers and HVAC techs
Painters and drywall crews
Estimators
Project managers and office managers at trade shops

Sample data

Every result on this page comes from this sheet, calculated by the same engine the Cellwise app uses. Change a number and watch the formulas react.

	A	B	C	D	E	F	G	H
1	Room	Length (ft)	Width (ft)	Wall height (ft)	Openings (sq ft)		Waste allowance	0.12
2	Bedroom 1	12.5	11	8	36		Drywall sheet (sq ft)	32
3	Bedroom 2	11	10.5	8	21		Markup on cost	0.25
4	Hallway	18	3.5	8	42		Crew rate ($/hr)	58
5
6	Cost line	Type	Budget	Actual	Crew hours	Change orders
7	Framing lumber	Material	2850	3120
8	Drywall and mud	Material	1640	1585		180
9	Framing labor	Labor	3480	3770	65
10	Drywall labor	Labor	2784	2610	45
11	Electrical	Subcontract	4200	4650		450
12	Paint and trim	Material	1150	980

What Excel does for construction and trades

Wall square footage for a room

The wall area of a rectangular room is its perimeter times the wall height: 2 x (length + width) x height. Then take off doors and windows. Measure openings as a total square footage per room (a standard 3 x 6.8 ft door is about 20 sq ft) and keep it in its own column so it is easy to check.

Many estimators leave small openings in on purpose, because the offcuts rarely get used. If that is how you work, put 0 in the openings column and use a smaller waste allowance instead. Just do not do both.

=2*(B2+C2)*D2-E2

Result: 340

Bedroom 1 has 2 x (12.5 + 11) x 8 = 376 sq ft of wall, minus 36 sq ft of openings: 340 sq ft to cover.

Drywall sheets for the whole job, rounded up

Add the wall area of every room, add the waste allowance, divide by the size of one sheet (32 sq ft for a 4 x 8), and round UP. SUMPRODUCT runs the wall-area formula on each room and adds the results, so you do not need a helper column.

ROUNDUP with 0 decimals always goes to the next whole number: 33.1 becomes 34. ROUND would turn 33.4 into 33 and leave you a sheet short on the last wall. Ceilings are not in this formula; add them as their own line (length x width) if you are hanging them.

=ROUNDUP(SUMPRODUCT(2*(B2:B4+C2:C4)*D2:D4-E2:E4)*(1+H1)/H2,0)

Result: 34

965 sq ft of wall plus 12% waste is 1,080.8 sq ft, or 33.8 sheets. Order 34.

Floor area for flooring or a ceiling

For several rooms, SUMPRODUCT multiplies each length by its width and adds the products in one step. It is the same as adding B2*C2, B3*C3 and B4*C4 by hand, but it keeps working when you add a room to the list.

For L-shaped rooms, split them into two rectangles on separate rows. It is easier to check than one clever formula.

=SUMPRODUCT(B2:B4,C2:C4)

Result: 316

137.5 + 115.5 + 63 = 316 sq ft of floor across the three spaces.

Turn cost into a quote with markup

Markup is a percentage added on top of cost. Price = cost x (1 + markup). With the markup in H3, change one cell and the whole quote updates.

The classic mistake is treating markup and margin as the same thing. A 25% markup on cost is only a 20% margin on the selling price, because the profit is divided by the bigger number. If you need a 25% margin, the price is cost / (1 - 25%), which is a 33.3% markup.

=ROUND(SUM(C7:C12)*(1+H3),2)

Result: 20130

$16,104 of budgeted cost with a 25% markup is a $20,130 quote. The $4,026 of markup is 20% of that price.

Check the job against budget, counting change orders

Compare actual cost with the original budget plus approved change orders. A change order adds scope, so its cost should raise the budget for that line; otherwise every job with extras looks like a loss on paper.

SUM accepts several ranges at once, so SUM(C7:C12,F7:F12) adds the budget and the change orders together. A negative result means you are under budget.

=SUM(D7:D12)-SUM(C7:C12,F7:F12)

Result: -19

The job looks $611 over the original budget, but $630 of that was approved change orders. Against the revised budget it is $19 under.

List the cost lines that ran over

FILTER keeps the line names where actual is more than budget plus change orders, and TEXTJOIN puts them in one readable cell for the weekly job meeting. The TRUE skips blanks.

FILTER and TEXTJOIN need Excel 365 or Excel 2021 or later. In older versions, add an Over/OK column with IF and filter it.

=TEXTJOIN(", ",TRUE,FILTER(A7:A12,D7:D12>C7:C12+F7:F12))

Result: Framing lumber, Framing labor

Framing lumber ($270 over) and framing labor ($290 over). Electrical used its full change order but did not go over.

Real labor cost per crew hour

Divide what labor actually cost by the crew hours logged. If it comes out above the rate you bid, you are paying for overtime, extra helpers, or hours that were not logged against the job.

SUMIF adds only the Labor lines, so materials and subs do not distort the number.

=SUMIF(B7:B12,"Labor",D7:D12)/SUM(E7:E12)

Result: 58

$6,380 of labor over 110 crew hours is exactly the $58 bid rate. The overrun on framing labor came from hours (65 against a budget of 60), not from the rate.

Practice: 8 exercises

Use the sample data above. Type a formula and press Check: it is graded by a real spreadsheet engine, the way Cellwise grades lessons.

1What is the floor area of Bedroom 1 in square feet?

Your formula for exercise 1

Show answer
=B2*C2 = 137.5. 12.5 x 11 = 137.5 sq ft.
2What is the total actual cost of the job so far?

Your formula for exercise 2

Show answer
=SUM(D7:D12) = 16715. SUM adds every actual cost in D7:D12: $16,715.
3By what percentage did framing lumber go over budget?

Your formula for exercise 3

Show answer
=(D7-C7)/C7 = 0.094736842105. ($3,120 - $2,850) / $2,850 = 9.5% over. Always divide by the budget, the number you planned against.
4What did materials actually cost in total?

Your formula for exercise 4

Show answer
=SUMIF(B7:B12,"Material",D7:D12) = 5685. SUMIF adds actuals only where Type is Material: $3,120 + $1,585 + $980 = $5,685.
5How many gallons of paint for Bedroom 2's walls, with 2 coats at 350 sq ft per gallon? Round up to whole gallons.

Your formula for exercise 5

Show answer
=ROUNDUP((2*(B3+C3)*D3-E3)*2/350,0) = 2. 323 sq ft x 2 coats = 646 sq ft, which is 1.85 gallons. ROUNDUP makes it 2, because the store sells whole cans.
6How many drywall sheets does the Hallway need, including the waste allowance?

Your formula for exercise 6

Show answer
=ROUNDUP((2*(B4+C4)*D4-E4)*(1+H1)/H2,0) = 11. 302 sq ft x 1.12 = 338.2 sq ft, or 10.6 sheets, so 11. Lock H1 and H2 with dollar signs if you copy it to other rooms.
7How many crew hours were budgeted for labor, using the crew rate in H4?

Your formula for exercise 7

Show answer
=SUMIF(B7:B12,"Labor",C7:C12)/H4 = 108. $6,264 of labor budget at $58 an hour is 108 hours. 110 were logged, so the crew ran 2 hours over.
8Your boss wants a 25% margin on price, not a 25% markup. Using the budget total and the 25% in H3, what price gives that margin? Round to cents.

Your formula for exercise 8

Show answer
=ROUND(SUM(C7:C12)/(1-H3),2) = 21472. $16,104 / 0.75 = $21,472. That is $1,342 more than the $20,130 markup quote, and its $5,368 profit is exactly 25% of the price.

Free templates for construction and trades

Guided project: Deck material takeoff and quote

Count boards and joists in whole pieces, price them and add your markup.

6 steps in the Cellwise app. Each step checks your formula in a real grid, with hints when you get stuck. Part of Cellwise Plus.

Open guided projects

Guides for these formulas

FAQ

How do I calculate square footage in Excel?

Multiply length by width in feet: =B2*C2. For several rooms, =SUMPRODUCT(B2:B4,C2:C4) adds every room in one formula. For wall area, use the perimeter times the height, 2*(length+width)*height, and subtract doors and windows.

How do I round up to whole sheets, boxes or gallons?

Use ROUNDUP with 0 decimal places: =ROUNDUP(1080.8/32,0) returns 34. ROUND goes to the nearest whole number and can round down, which leaves you short on site.

How do I add markup to a cost in Excel?

Multiply the cost by 1 plus the markup: =cost*(1+25%). If you want a target margin instead, divide: =cost/(1-25%). Those give different prices, so be sure which one you mean.

Should I use Excel or job management software?

Excel is enough for estimates and job cost reports on a handful of jobs at a time, and you can see every formula. When you run many jobs with several people entering costs, dedicated software that links purchasing and payroll saves re-typing.

Excel for other fields

Updated November 2, 2026