Estimating and bidding

How to estimate a construction project

Estimate a construction project by breaking the scope into cost codes, measuring quantities, pricing labor, material, equipment, and subcontracts, adding general conditions and contingency, then applying overhead and profit. Every number should trace back to a drawing, a quote, or your own cost history.

Two construction professionals review paper plans beside a tablet at a jobsite workbench.
Plan reviews connect field conditions, drawings, and the next decisions on a job. AI-generated illustration.

To estimate a construction project, read the full bid documents first, then break the work into cost codes and do a quantity takeoff for each one. Price self-performed work as labor hours times a burdened rate plus material and equipment. Collect and level subcontractor quotes for everything you will sub out. Add the job's general conditions (supervision, temporary facilities, cleanup, permits, insurance that is job-specific), a contingency sized to the risk, and finally overhead and profit. Then check the total against your own history for similar jobs before it goes out. The estimate is the budget the job will be run on, so it has to be built in a way operations can use.

That is the process in one paragraph. The skill is in the details: catching scope that sits in the specs but not the drawings, pricing labor from your real productivity rather than hope, and knowing which sub quotes are complete.

The estimating process, step by step

1. Decide whether to bid at all

Estimating time is expensive. Before starting, check the job against your criteria: type of work, size, owner, location, bonding needs, and your current backlog. See how to decide which construction jobs to bid.

2. Read everything before measuring anything

Drawings, specifications, addenda, the bid form, the general and supplementary conditions, and any geotechnical or hazardous material reports. Make a list of questions and submit them before the RFI deadline. Note what the bid form requires: alternates, unit prices, allowances, a bid bond. Missing an addendum is one of the most common reasons bids get thrown out or lose money.

3. Set up the estimate by cost code

Organize the estimate the way you will track costs on the job. Many contractors use a CSI MasterFormat-based structure or their own cost codes. If the estimate and the job cost system use the same codes, the handoff to operations is easy and job cost reports actually compare to something.

4. Do the takeoff

Measure quantities from the drawings: square feet of slab, linear feet of wall, number of doors, tons of steel. Use the units your pricing uses. Record assumptions as you go. For method, see how to do a quantity takeoff.

5. Price self-performed labor

Labor is where estimates go wrong most often. Quantity times your production rate (hours per unit) gives hours. Hours times a burdened rate gives dollars. The burdened rate includes wages plus payroll taxes, insurance, and benefits; see labor burden. Production rates should come from your own completed jobs. Read how to estimate labor hours for construction.

6. Price material and equipment

Get current supplier quotes for major materials, add waste factors, delivery, and sales tax where it applies. Price equipment by the duration it will be on site, including rental, fuel, and mobilization.

7. Collect and level subcontractor quotes

Send clear bid packages to several subs per trade. When quotes come in, compare scope line by line, not just totals. One sub may exclude the permit, another the cleanup. Plug gaps with your own number. See how to level subcontractor bids.

8. Add general conditions

Supervision, project management time, temporary toilets, fencing, dumpsters, trailers, small tools, final cleaning, and job-specific insurance and bonds. Price them by duration from a realistic schedule. See how to price general conditions.

9. Add contingency and escalation

Contingency covers estimating risk: incomplete drawings, unknown site conditions, quantities that may grow. Size it to the job, and do not use it to hide a low labor number. If the job runs long or prices are volatile, consider escalation separately. See how to estimate construction contingency.

10. Apply overhead and profit

Overhead recovers your office, estimators, vehicles, and other company costs. Profit is what is left. Know whether you are thinking in markup or margin; they are not the same. Read markup vs margin in construction.

11. Review before it goes out

A second person checks the big numbers: quantities on the five largest line items, labor hours against similar past jobs, and every sub quote's exclusions. Compare cost per square foot to your history. If it is far off, find out why.

Worked example: a small commercial tenant improvement

Say a GC estimates a 4,000 square foot office tenant improvement. The firm self-performs framing, doors, and finish carpentry and subs out the rest.

Example estimate summary
CategoryAmountHow it was priced
Self-performed labor$62,0001,000 hours at a $62 burdened rate
Material (self-performed scopes)$48,000Supplier quotes plus 7% waste
Subcontracts$210,000Leveled quotes: MEP, drywall, flooring, paint, ceilings
Equipment$6,000Lift and tool rental, 8 weeks
Direct cost subtotal$326,000
General conditions$28,000Super, PM time, temp facilities, cleanup, 10 weeks
Contingency (3%)$10,620On direct cost plus general conditions
Cost subtotal$364,620
Overhead and profit markup (12%)$43,754Applied to cost subtotal
Bid price$408,374

That 12 percent markup works out to about 10.7 percent of the selling price ($43,754 divided by $408,374). An estimator who thinks "12 percent margin" here is overstating profit by more than a point. At $408,374 the job prices out around $102 per square foot, which the reviewer compares to recent similar TIs before signing off.

How estimates change as design develops

Not every estimate is a hard bid on finished drawings. Owners and developers often ask for numbers much earlier.

  • Conceptual or budget estimates come from square foot or unit costs on similar past jobs, before drawings exist. They help an owner decide whether the project is feasible. State the basis and the range clearly.
  • Design development estimates use partial drawings. You can take off major quantities but must carry allowances for what is not designed yet.
  • Hard bid or GMP estimates come from complete construction documents with detailed takeoffs and sub quotes.

The method in this guide applies at every stage. What changes is how much is measured versus assumed, and how large the contingency needs to be. Label every early estimate with the drawing date and its assumptions, so nobody treats a budget number as a firm price later.

Mistakes to avoid

  1. Skipping the specs. Scope often hides in specification sections, such as testing, warranties, or attic stock.
  2. Using someone else's production rates. Published rates are a starting point. Your crews' history is the real number.
  3. Unburdened labor. Wages alone understate labor cost significantly.
  4. Taking the lowest sub quote without leveling. The cheapest quote often has the biggest exclusions.
  5. General conditions as a percentage. Price them by duration. A job that runs eight extra weeks costs eight extra weeks of supervision.
  6. No record of assumptions. The PM cannot run a budget whose assumptions live only in the estimator's head.
  7. Confusing markup and margin. See the example above.

Templates and tools that help

A construction estimate template and a bid leveling template cover most of the work on smaller jobs. For bids, add how to write bid clarifications and exclusions. GAO's Cost Estimating and Assessment Guide is a free, detailed reference on estimating practice, written for government programs but useful for documenting assumptions and checking an estimate.

Smart Business Automator carries the estimate into the project as the job budget by cost code, so job costing starts from the numbers that won the work. Its document data extraction can pull line items from supplier and sub quotes. See estimate to project handoff automation.

Frequently asked questions

What are the main parts of a construction estimate?

Direct costs (labor, material, equipment, subcontracts), general conditions, contingency, overhead, and profit. Bid estimates may also include bonds, permits, escalation, and allowances required by the bid form.

How long does it take to estimate a construction project?

It ranges from an hour for a small service job to weeks for a large commercial bid. The size of the drawing set, number of trades, and how many sub quotes you need drive the time.

How accurate should a construction estimate be?

Accuracy depends on how complete the design is. Estimates on early concept drawings carry wide ranges, while bids on complete construction documents should be tight. Track your final costs against estimates to learn your own accuracy.

What is the difference between an estimate and a bid?

The estimate is your calculated cost plus markup. The bid is the price you submit, which may be adjusted from the estimate for strategy, competition, or risk, along with clarifications, exclusions, and any required forms.

Should contingency be shown to the owner?

On a lump sum bid it is usually built into the price. On cost-plus or GMP contracts, contingency is often a visible line item with rules for how it can be used. Follow the contract form.

Sources

  1. U.S. Government Accountability Office: Cost Estimating and Assessment Guide (GAO-20-195G)
Written and edited by

Maurice Francois writes and edits construction operations guides for Smart Business Automator. More from Maurice on the Scaling Legends podcast.

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