Construction takeoff units of measure look like a small topic until a bid goes wrong because of one. A price quoted per thousand square feet gets used as a price per square foot. Concrete is ordered in cubic feet instead of cubic yards. Rebar is measured in linear feet and priced in tons. Someone mixes decimal feet with feet and inches and a room ends up 6 inches too long. This guide explains the units that estimators use, the conversion factors worth memorizing, how to round to units you can actually buy, and how to check your work so that unit errors do not reach the bid.
If you want quantities prepared with the right units for every trade, our quantity and material takeoff services deliver them organized by trade and by purchasable unit. If you want to master the units yourself first, read on.
Why units matter in an estimate
Every cost in an estimate is a quantity multiplied by a unit price, and the two must use the same unit. The quantity comes from the takeoff, and the unit price comes from a supplier quote, a subcontractor bid, a labor rate or a cost database such as the ones described in our guide to RSMeans and construction cost data. If the takeoff counts square feet and the price is per square yard, the result is wrong by a factor of nine, and nothing in the spreadsheet will warn you.
Standard classification systems help keep this organized. The Construction Specifications Institute publishes MasterFormat, which organizes work by division and section and is used to structure specifications and cost data, and which many estimators use to sort takeoff lines. Each section tends to have a customary unit of measure, such as cubic yards for concrete or squares for roofing.
The common units and what they mean
- EA (each): counted items such as doors, fixtures, drains, light fixtures and anchor bolts.
- LF (linear foot): measured length, such as pipe, conduit, wall base, flashing, sealant joints and curbs.
- SF (square foot): area, such as drywall, flooring, paint, insulation and slab.
- SY (square yard): area in yards, used for paving, carpet and some sitework. One square yard is 9 square feet.
- CF (cubic foot) and CY (cubic yard): volume, used for concrete, excavation, backfill and aggregate. One cubic yard is 27 cubic feet.
- SQ (square): a roofing unit equal to 100 square feet.
- CSF: 100 square feet. MSF: 1,000 square feet. The letter C means one hundred and M means one thousand, a Roman numeral convention that is still common in pricing.
- BF (board foot): a lumber volume equal to 144 cubic inches, or one square foot at one inch thick. MBF is 1,000 board feet.
- LB, CWT and TON: weight. One CWT is 100 pounds, and one short ton is 2,000 pounds.
- GAL (gallon): liquid volume, used for paint, sealants, coatings and adhesives.
- SFCA: square feet of contact area, used for formwork.
- LS (lump sum): a single price for a defined scope with no unit quantity, used for items that cannot be measured sensibly.
Be careful with M. In pricing, per M means per thousand, so brick quoted at a price per M is the price of 1,000 bricks. In some contexts, M also means a million, and in metric it means meters, so write out the unit whenever there could be doubt.
Conversion factors worth memorizing
Length, area and volume
- 1 foot = 12 inches. 1 yard = 3 feet.
- 1 square foot = 144 square inches. 1 square yard = 9 square feet.
- 1 acre = 43,560 square feet.
- 1 cubic foot = 1,728 cubic inches. 1 cubic yard = 27 cubic feet.
- 1 US gallon = 231 cubic inches, which is about 0.1337 cubic feet. One cubic foot is about 7.48 gallons.
Weight and density
- 1 short ton = 2,000 pounds. A long ton is 2,240 pounds, and a metric tonne is about 2,204.6 pounds.
- Steel weighs about 490 pounds per cubic foot.
- Normal-weight concrete weighs roughly 150 pounds per cubic foot, or about 4,000 pounds per cubic yard.
- Water weighs about 62.4 pounds per cubic foot, or about 8.34 pounds per gallon.
Metric
- 1 inch = 25.4 millimeters. 1 foot = 0.3048 meters.
- 1 square meter = about 10.764 square feet.
- 1 cubic meter = about 1.308 cubic yards.
Inch fractions to decimals
1/8 = 0.125, 1/4 = 0.25, 3/8 = 0.375, 1/2 = 0.5, 5/8 = 0.625, 3/4 = 0.75 and 7/8 = 0.875. When you multiply, always convert fractions first. A 6 inch slab is 0.5 feet, an 8 inch wall is 0.667 feet and a 3/8 inch plate is 0.375 inches.
Feet-and-inches versus decimal feet
This is one of the most common sources of small errors. A dimension written as 12 feet 6 inches is 12.5 feet, not 12.6. Divide the inches by 12: 8 feet 9 inches is 8 + 9/12 = 8.75 feet. Many digital takeoff tools do this for you, but spreadsheets do not, so decide on one format and keep it consistent in every formula.
Reading scales on drawings
Paper drawings and PDFs are scaled, and a measurement means nothing until you know the scale. At 1/8 inch = 1 foot, one inch on paper represents 8 feet. At 1/4 inch = 1 foot, one inch is 4 feet. Civil drawings often use engineering scales such as 1 inch = 20 feet. Area scales with the square of the length scale. For a drawing at 1/8 inch = 1 foot, one square inch on paper represents 64 square feet. A room measured as 3.5 inches by 2 inches on paper is 28 by 16 feet, or 448 square feet, and 7 square inches x 64 gives the same result.
With PDF takeoff software, always calibrate against a known dimension on each sheet and check it against a second dimension, since sheets can be printed or exported at a different scale than the title block says. Our guide to BIM and digital takeoff workflows covers the tools, and our post on reading construction plans for estimating covers scales and sheet types.
Net quantity, waste and purchasable units
The takeoff produces a net quantity, the amount needed in the finished work. Purchasing and pricing use a gross quantity, which includes waste and is rounded to the way material is sold. Keep these separate on the estimate so a reviewer can see both.
- Sheets: drywall comes in 4 x 8 foot sheets of 32 square feet, and plywood is similar. A net of 4,000 square feet is exactly 125 sheets before waste.
- Cartons and boxes: tile and plank flooring are sold by the carton with a fixed square footage, so round up to full cartons. Our post on flooring waste factors by material shows the arithmetic.
- Rolls: carpet, sheet vinyl and membranes come in fixed widths, so the layout decides the quantity.
- Bags and buckets: mortar, grout and joint compound are sold in set sizes.
- Truckloads: concrete and aggregates are ordered by the cubic yard or ton, with minimums and short-load fees.
- Pallets and cubes: brick and block are delivered by the pallet or cube.
Typical units by trade
- Concrete: CY for volume, SFCA for formwork, LB or TON for rebar, SF for finishing. See how to calculate concrete yardage, rebar and formwork.
- Masonry: EA or per M for units, CF or bags for mortar, LF for flashing and reinforcement. See how to calculate CMU block and brick quantities.
- Structural steel: TON for members, SF for deck, EA for studs and anchor rods. See how to calculate structural steel tonnage.
- Roofing: SQ for membrane, BF or SF for insulation, LF for edge metal, EA for drains and penetrations. See low-slope roofing takeoff.
- Drywall and painting: SF, sheets or MSF for board, GAL for paint, LF for trim. See how to calculate drywall quantities and how to estimate painting.
- Sitework: CY for excavation and fill, SY for paving, LF for pipe and curbs.
- MEP: LF for pipe, conduit and cable, EA for fixtures, devices and equipment, and LB for ductwork in some pricing methods.
- Lumber: BF or pieces by length, and SF for sheathing.
Bank, loose and compacted volumes
Earthwork adds a twist: the same soil has different volumes in different states. Bank cubic yards (BCY) are measured in place before digging, loose cubic yards (LCY) are measured after excavation when the soil has swelled, and compacted cubic yards (CCY) are measured after placement and compaction. Trucks carry loose volumes, while quantities from the plans are usually bank or compacted. Swell and shrinkage factors depend on the soil and are given in the geotechnical report or your own records. As an illustration, if 1,000 BCY swells by 25 percent, it becomes 1,250 LCY, and a truck that hauls 12 LCY needs 1,250 / 12 = 104.2, so 105 loads.
Conversion practice
These examples are illustrative and show the same checks you should run on real quantities.
- Concrete: 2,430 cubic feet / 27 = 90 cubic yards.
- Rebar: 12,000 linear feet of #5 x 1.043 pounds per foot = 12,516 pounds, or 6.26 tons.
- Lumber: 120 pieces of 2 x 6 x 16 feet. Board feet per piece = 2 x 6 x 16 / 12 = 16, so the total is 1,920 board feet, or 1.92 MBF. Remember that nominal sizes are not actual sizes, so a 2 x 4 measures about 1.5 by 3.5 inches, but board feet are calculated from nominal dimensions.
- Roofing: 10,600 square feet / 100 = 106 squares.
- Pricing per MSF: a supplier quotes drywall at $450 per MSF, which is $0.45 per square foot. For 4,000 square feet the cost is 4 x $450 = $1,800.
- Paint: 1,000 square feet with two coats at 350 square feet per gallon = 5.7 gallons, so order 6.
Unit price versus assembly price
A unit price covers one item, such as a linear foot of conduit or a square foot of drywall. An assembly price covers a complete system measured in one unit, such as a square foot of partition including studs, board, finishing and paint, or a linear foot of parapet including coping, flashing and blocking. Assemblies are quick and useful for budgets and for checking, while unit pricing is better for bids because it shows what is and is not included. Our guide to construction estimate templates and examples shows how both are laid out on an estimate, and our quantity takeoff methods post explains when to use each.
A checklist to prevent unit errors
- Write the unit next to every quantity and every price, in the cell or the label, not just in your head.
- Convert everything to one system before multiplying: all feet, or all inches.
- Check that the quantity unit matches the price unit before you multiply.
- Keep net quantity, waste and gross quantity in separate columns.
- Round up only at the purchase step, not at every line.
- Run a sanity check: divide the total by the building area or other driver and compare it with a similar past job.
- Have someone else review the unit column of the summary sheet.
Common unit-of-measure mistakes
- Dividing cubic feet by 12 or 9 instead of 27 to get cubic yards.
- Using a price per MSF as a price per SF, or per M as per each.
- Entering 12 feet 6 inches as 12.6.
- Mixing short tons, long tons and metric tonnes.
- Calculating board feet from actual rather than nominal sizes.
- Using bank yards where loose yards are needed for hauling.
- Forgetting that area scales by the square of the length scale.
- Pricing flooring by net area when the supplier sells full cartons.
More errors of this kind and their effect on bid accuracy appear in our list of common construction estimating mistakes, and our material takeoff guide shows how to build a clean material list.
Frequently asked questions
What does MSF mean in construction?
It means 1,000 square feet. A price of $450 per MSF is $0.45 per square foot.
How many square feet are in a roofing square?
100 square feet.
How do I convert cubic feet to cubic yards?
Divide by 27.
What is a board foot?
A unit of lumber volume equal to 144 cubic inches, calculated as thickness in inches x width in inches x length in feet, divided by 12.
What is the difference between SF and SFCA?
SF is any area. SFCA is the specific area of formwork in contact with concrete, which drives forming labor and material.
Should I take off in imperial or metric units?
Use the units of the drawings and the price sources, and convert at the end if needed. On US projects this is almost always imperial. Convert explicitly and document the factors.
Get takeoffs with consistent, purchasable units
We deliver quantities by trade with clear units, net and gross columns and the waste and conversion assumptions stated, so you can apply supplier quotes and labor rates without converting anything. See our quantity and material takeoff services, our cost estimation service, or the full list of estimating services by trade.