Concrete & Masonry

Steel Rebar Calculator

Use this steel rebar calculator to estimate a simple two-direction reinforcement grid for a rectangular slab. Enter slab dimensions, rebar spacing, stock bar length and weight per foot to estimate total linear footage, stock pieces and approximate steel weight.

✓ Free✓ Instant result✓ No signup

Step 1

Enter project details

Slab length ft Slab width ft Rebar spacing in Lap / waste allowance % Stock bar length ft Bar weight lb/ft

Planning estimate only. Confirm local prices, supplier specifications and site conditions before ordering.

Step 2

Your estimate

Bars running lengthwise—

Bars running widthwise—

Total rebar—

Approx. stock bars—

Approx. steel weight—

This estimates quantity only. Bar size, spacing, laps, cover and reinforcement design must follow approved plans and applicable code requirements.

Optional next step

Request a local concrete project quote

Complete three short steps to check for available local professionals.

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How matching works

ProjectMetrica helps route your concrete / reinforcing project request to participating platform partners or service providers when an eligible match is available.

Availability depends on ZIP code, service and project details.
ProjectMetrica is not the contractor and may receive compensation for an accepted request.

ProjectMetrica collects this request and may share it with participating service providers and platform partners for the home-improvement project you selected. The consent session is independently recorded. See the Privacy Policy.

1 Project 2 Timing 3 Contact

Step 1 of 3

What kind of project is it?

Choose the service details and enter the five-digit project ZIP code.

Project scope Location ZIP code

Step 2 of 3

When are you planning the work?

These details help make the request more relevant. No availability check is sent yet.

Hiring status Project timeframe Can you authorize work on the property? Project details

Step 3 of 3

Where can professionals reach you?

Use the contact details for the property where the project is planned. This usually takes about a minute.

Your request stays focused on this project

Your address helps check local service availability and is not posted publicly.
Submitting is free and does not require you to hire anyone.
Your details are used to process and route the home-service request described here.

First name Last name Project street addressEnter the street address where the work is planned. You can correct every address field before submitting. City State Phone Email

By submitting, you confirm that you are at least 18 years old and that the information you provided is accurate.

Your request may be sent to participating home-improvement providers when a qualifying match is available.

Before you order

Check local supplier specs

Density, bag coverage, pallet size and recommended installation depth can vary by material and supplier.

Professional installation

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Connect with a local professional for a site-specific estimate.

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Formula & assumptions

How the steel rebar calculator works

Bars in each direction are based on slab dimensions and center-to-center spacing. Total linear feet equals the combined length of both bar directions, with waste applied before stock pieces and weight are estimated.

For a better estimate

Structural reinforcement must follow approved plans, code requirements and engineering guidance.
Account for required concrete cover and lap lengths rather than placing steel directly at slab edges.
This calculator is for quantity planning only and does not design reinforcement size or spacing.

Useful project tools

Tools that can help with this project

Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases.

Rebar tie wireSecure reinforcing steel intersections. View on Amazon → Rebar tying toolSpeed up manual tie-wire work. View on Amazon → Measuring tapeLay out bar spacing and slab dimensions. View on Amazon →

Common questions

Frequently asked questions

How do I calculate rebar quantity?+

Estimate the number of parallel bars from spacing in each direction, multiply each count by its run length, then add lap and waste allowance.

What rebar spacing should I use?+

Spacing is a design decision and depends on slab thickness, loads, soil and local requirements. Use the spacing specified by the project design.

Does this calculator include rebar laps and waste?+

Yes, through the adjustable allowance, but actual lap lengths and detailing must follow the approved reinforcement plan.

Enter project details

Your estimate

Request a local concrete project quote

What kind of project is it?

When are you planning the work?

Where can professionals reach you?

Check local supplier specs

Compare local project quotes

How the steel rebar calculator works

For a better estimate

Tools that can help with this project

Frequently asked questions

Guides for this project

Rebar Spacing Concrete Slab Guide: Quantity Planning

Retaining Wall Rebar Guide: Quantity and Planning Basics

How Much Concrete Do I Need?

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