Free Rebar Calculator Widget
The embedded Rebar Calculator converts a rectangular slab's dimensions, bar size and spacing into a two-way rebar grid — total bars, linear feet, weight and stock bars to buy. It suits rebar and building-material suppliers, and concrete contractor sites.
It's a single iframe — free, responsive, no registration, and it adds no link, ad or tracking script to your page.
Live preview
The embed adds no link, no ads and no tracking to your page. Prefer a guided version with a preview? Use the embed builder.
One small ask
Nothing links back to us from the widget itself. If your readers find it useful, please add a credit link to the Rebar Calculator somewhere on your page — that's what keeps it free to maintain and helps others discover it.
Where the Rebar Calculator widget fits
- A rebar or building-material supplier's ordering page
- A "how much rebar do I need" article
- A concrete contractor's slab project-planning page
How to add it to your site
- Plain HTML: paste the snippet where you want the calculator to appear.
- WordPress: add a “Custom HTML” block and paste the snippet in. Avoid the “Paragraph” block — it strips iframes.
- Squarespace / Wix / Webflow: add an “Embed” or “Custom Code” / “HTML” element and paste the snippet.
- The second line (
embed.js) is optional — it just auto-sizes the frame height. You only need it once per page even with several calculators.
Sizing & responsiveness
Set the width to 100% to fill the column it sits in, or a fixed pixel value for a sidebar or narrow layout. Height is handled for you: with embed.js the frame grows and shrinks to fit the calculator (including after someone runs an estimate); without it, the frame stays at 900px and everything still works, just with an inner scrollbar on small screens.
Questions from site owners
Is it really free? Any catch?
Yes, free. No account, no API key, no usage limits, and no link, ads or tracking added to your page. The only thing asked is that, if the tool is useful to your readers, you add a plain credit link back to the calculator somewhere on the page.
Will it slow my page down or track my visitors?
No. The calculator loads in an iframe so it never blocks your page, it ships no third-party ad or analytics scripts onto your site, and it sets no cookies on your visitors. The optional resizer script is a few KB and loads asynchronously.
Does it support different bar sizes and spacing?
Yes — #3 through #6 rebar, with adjustable spacing and edge clearance.
Does it give weight, not just bar count?
Yes — total weight in pounds is calculated from the bar size's standard weight per foot, useful for ordering by weight.
Can I resize it or set a fixed width?
Yes. Choose responsive (100%) or a fixed-pixel width when you copy the code; height auto-fits the calculator, with a fixed fallback if the resizer script is blocked.
Just need to run the numbers yourself? Use the full Rebar Calculator — it has the formulas, a worked example and an FAQ. Or see all embeddable calculators.