Concrete planning tool

Concrete Rebar Calculator

Translate an already specified rectangular reinforcing grid into bar counts and linear footage.

Reinforcing takeoff

Enter your concrete rebar grid

Planning takeoff only. Enter cover, maximum spacing, and bar size from approved project documents or a qualified designer.

Plan responsibly

Before You Build

This project may be subject to local permit, zoning, site, or structural requirements.

Reinforcement and concrete detailsVerify the locally adopted code, approved plans, specified bar size, spacing, cover, supports, laps, openings, and concrete requirements.
Design, permit, and inspection requirementsConfirm whether engineered documents, permits, and reinforcement inspections are required before placing concrete.

Local requirements control: Model-code references do not confirm the code edition, amendments, zoning rules, permit requirements, or site criteria adopted for your project.

Grid takeoff is not reinforcement design: Bar counts and linear footage do not establish structural adequacy, required reinforcement, development length, splice length, anchorage, crack control, or code compliance.

View code references

Model-code reference

2021 IRC, Section R506.2.4

Reinforcement support: The IRC contains a model-code provision for supporting reinforcement where it is provided in residential concrete floors on ground. It does not select bar size, spacing, cover, laps, or a reinforcement design.

Source: ICC Digital Codes: 2021 IRC Section R506.2.4 · Reviewed 2026-08-24

Local requirements may differ. A model-code reference does not confirm the code edition, amendments, zoning rules, or permit requirements adopted where the project is located.

Model-code references

2021 IRC, Section R506.2.4: Reinforcement support. Source: ICC Digital Codes: 2021 IRC Section R506.2.4. Reviewed 2026-08-24.

Local requirements may differ. Verify the adopted code, amendments, zoning rules, and permit requirements with the local authority.

Methodology

How we calculate this

Cover is measured to the bar surface. The calculator adds half the nominal bar diameter to locate each edge-bar centerline, divides the usable centerline span into equal spaces no greater than the entered maximum, and totals physical bar lengths between the entered surface covers.

centerline setback = cover + diameter ÷ 2; bars = ceil(centerline span ÷ entered spacing) + 1

Inputs, not recommendations

Cover, spacing, and bar size must come from project documents or a qualified designer. This calculator does not select or design reinforcement.

Verify before purchasing

Confirm laps, hooks, supports, openings, edge conditions, and placing details separately; they are not included.

Worked examples