How to Estimate Construction Costs: Takeoff, Labor, Materials, and Markup

The average construction bid has a 15–20% margin of error — meaning a contractor who estimates a project at $500,000 may actually spend $575,000 to complete it. That gap comes from inaccurate quantity takeoffs, understated labor hours, missed scope items, and markup that doesn't cover actual overhead. On a project with a 10% margin, a 15% cost overrun turns a $50,000 profit into a $25,000 loss.

Accurate estimating is not guesswork refined over time. It's a systematic process: measure the scope, price the labor, price the materials, add equipment and general conditions, apply overhead, and add profit. Each step has specific methods and common failure points. Contractors who follow the process consistently win profitable work. Contractors who estimate by feel or by adjusting last year's numbers sign contracts they can't fulfill at the margin they expected.

This guide covers the full estimating process — from reading plans to submitting a number — including how to calculate burdened labor rates, how to evaluate subcontractor bids, what overhead allocation looks like in practice, and how historical data from construction time tracking software builds the productivity database that makes every future estimate more accurate.

The 5 Types of Construction Estimates

Different project phases require different estimate types. Using the wrong type at the wrong phase — giving a detailed budget-level estimate at conceptual design, or giving a rough order-of-magnitude at bid time — creates problems for both contractor and owner.

Estimate Type

When Used

Accuracy Range

Basis

Order of Magnitude

Early concept, feasibility

±30–50%

$/SF, historical project cost

Schematic / Conceptual

Schematic design

±20–30%

Assemblies, system costs

Design Development

DD documents

±10–20%

Preliminary quantities

Construction Document

Full bid documents

±5–10%

Complete quantity takeoff

Definitive / Control

Awarded project

±3–5%

Originally published at https://blog.tasktag.com on July 16, 2026.