Put a free calculator on your site
Every calculator here can be embedded in one paste — on a contractor site, a supply-store product page, a how-to post. No account, no API key, no ads inside the widget, and the math keeps improving without you touching the snippet again.
Build your snippet
Live preview
How the auto-height works
An iframe cannot measure itself from the outside, so the widget posts its own height to your page and embed.js applies it — on load, when the visitor presses Calculate and the results appear, and when the column is resized. The script is about 500 bytes, loads once no matter how many widgets you place, and only listens to messages coming from thejobcalc.com.
Leave it out if you would rather not add a script: the iframe keeps the fixed height from the snippet and scrolls inside itself. Nothing breaks.
Terms — the short version
- Free, commercial use included. Contractor sites, supply stores, affiliate blogs — all fine.
- Keep the credit. The line under the widget, and the link in the snippet. That link is the whole price.
- No ads, no cookies, no consent banner. The widget asks your visitors for nothing and stores nothing on their device.
- Do not re-host it. Point the iframe at thejobcalc.com so corrections and updated material yields reach your readers automatically.
- Estimates, not engineering. Same disclaimer as the rest of the site: quantities vary by brand and by jobsite, and local code wins.
We reserve the right to stop serving a widget to a site that strips the credit or presents the numbers as its own professional advice.
Every widget
| Calculator | What it works out | |
|---|---|---|
| Concrete Calculator | Cubic yards and bag counts for slabs, footings, columns and post holes. | Preview |
| Gravel & Base Calculator | Tons and cubic yards of gravel, crushed stone or sand for driveways and bases. | Preview |
| Tile Calculator | How many tiles and boxes to buy, with grout joints and a cut allowance. | Preview |
| Drywall Calculator | Sheets, screws, joint compound and tape for a room or a known area. | Preview |
| Insulation Calculator | Batt insulation bags for walls or attic, with an R-value guide. | Preview |
| Paint Calculator | Gallons and cans for walls and ceilings, with doors and windows deducted. | Preview |
| Mulch & Soil Calculator | Cubic yards, bags and weight for mulch, topsoil, compost and gravel. | Preview |
| Sod & Grass Seed Calculator | Rolls or pallets of sod, or pounds of grass seed, for any lawn area. | Preview |
| Square Footage Calculator | Area of any shape, added into a running total, with cost per square foot. | Preview |
| Roof Pitch Calculator | Pitch, angle, slope factor, roof area, squares and shingle bundles. | Preview |
| Fence Calculator | Posts, rails, pickets and concrete bags for a run of fence. | Preview |
| Deck Board Calculator | Deck boards, joists and screws for a deck of any size. | Preview |
| Stair Calculator | Risers, treads, total run, stringer length and angle from a total rise. | Preview |
| Hourly to Salary Calculator | Convert an hourly wage to annual, monthly, biweekly and weekly pay — or back. | Preview |
| Overtime Pay Calculator | Time-and-a-half and double-time pay for a week with overtime hours. | Preview |
| Take-Home Pay Calculator | What lands in your account each paycheck, using your own effective tax rates. | Preview |
| Concrete Driveway Cost Calculator | Itemised driveway estimate from your local prices: concrete, base, labour, finish and removal. | Preview |
| Roof Replacement Cost Calculator | Itemised re-roof estimate from your local prices: squares from footprint and pitch, tear-off, materials, labour, flashing. | Preview |
| Deck Cost Calculator | Itemised deck estimate from your local prices: footings, framing, decking, railing, stairs and labour by height. | Preview |
Need one we have not built? Tell us — the ones people ask for twice get built.
Frequently asked questions
Is it really free?
Yes, including on commercial sites. The only condition is that you keep the credit link that comes with the snippet.
Will the widget slow my page down?
The iframe is set to loading="lazy", so it is only fetched when the visitor scrolls near it. The page itself is about 10 KB with no external fonts, images or libraries.
Does it collect anything from my visitors?
No cookies, no local storage, no forms sent anywhere. The numbers your visitor types never leave their browser: the whole calculation runs client-side.
Do I have to add the embed.js script?
No. It only makes the frame resize itself to fit the results. Without it the iframe keeps the fixed height in the snippet and scrolls internally.
Can I change the colours?
Pick a theme and an accent colour on this page and the snippet updates. Anything beyond that would mean re-hosting the widget, which the terms do not allow.
What happens if you change a calculator?
Your embed picks up the change on the next page load. Formulas are versioned in one place and covered by tests, so corrections reach every embed at once.