Put exact calculators on your site in one paste
Free, responsive, and mathematically exact. Configure the look below, copy the snippet, and paste it anywhere — WordPress, Ghost, Squarespace, or plain HTML. No API keys, no fees, no tracking. Every widget auto-resizes to fit its container.
WordPress
Paste a calculator’s page URL on its own line and WordPress embeds it — no plugin needed. For a block with every calculator in the inserter, install the plugin:
Download plugin (ZIP)Plugins → Add New → Upload Plugin
Shopify
Add the snippet below through Custom Liquid in the theme editor. Product and page descriptions strip scripts, so use a theme section there — or the no-script format, which survives any editor.
Nutrition
Nutrition converter (density-aware)
Weight ↔ volume ↔ nutrient for 100+ USDA foods. Density-aware: 1 cup of flour and 1 cup of honey weigh different amounts — most converters get this wrong.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Electrical
Wire gauge calculator
Minimum AWG conductor for a load per NEC 2023 Table 310.16 — checks both ampacity and voltage drop. Copper or aluminum, single or three-phase.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Converters
Unit converter
Any of 800+ conversions across length, mass, temperature, volume, and more. Server-rendered result for instant load.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Solar
Solar panel system sizer
System size, panel count, payback and 25-year savings from a monthly kWh bill — using that state's real peak sun hours (NREL PVWatts v8) and electricity rate (EIA), not a national average.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Roofing
Roofing material calculator
Squares, bundles and installed cost from a floor-plan footprint. Applies the pitch slope factor and a waste allowance matched to the roof shape — the two things a flat area × price estimate gets wrong.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
HVAC
BTU / AC sizing calculator
Cooling and heating load for a room, then the nearest standard equipment size — simplified Manual J with climate zone, insulation, sun exposure and occupancy.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Construction
Concrete calculator
Cubic yards, bag count and cost for a slab, footing or pad. Bag yields are the real published ones (0.375 / 0.45 / 0.6 cu ft), so the count matches what the visitor has to buy.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Drywall sheet calculator
Sheets, area and cost for a room. Deducts real door and window openings and adds a waste factor, instead of billing the visitor for wall they will never board.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Freight & shipping
Dimensional weight calculator
Billable weight for a parcel against the carrier's real divisor (UPS/FedEx 139, USPS 166). Shows whether the shipment bills on actual or dimensional weight — the surcharge most shippers find out about on the invoice.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Freight class calculator
NMFC freight class from dimensions and weight, via the standard 18-tier density table. The number a shipper needs before an LTL carrier will quote.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Industrial
Material weight & volume converter
Tons ↔ cubic yards ↔ gallons for 119 real materials, from ready-mix concrete to diesel. Densities are sourced and carry their measured range, so a gravel estimate is not a single made-up number.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
Finance
Depreciation schedule calculator
MACRS or straight-line schedule with the tax saving per year, from the IRS Publication 946 half-year-convention tables. Full year-by-year table, not just a first-year number.
CSS preset previews
Click a visual sample—the real widget preview updates instantly.
The classic embed: auto-resizing iframe plus the loader script.
How to embed
Two ways — both fully responsive.
1. Copy the snippet (easiest)
Use the “Copy code” button on any widget above. It includes the small embed.js loader that keeps the iframe sized to its content.
2. Placeholder (auto-build)
Drop a placeholder and let the loader build the iframe:
<div data-et-tool="convert/length/meters-to-feet"
data-theme="auto" data-accent="#1d4ed8"
data-density="compact" data-controls="filled"
data-result-style="subtle" data-button-style="pill"
data-surface-style="gradient" data-et-height="220"></div>
<p style="font-size:12px;text-align:center">
<a href="https://www.experttoolkit.net/us/convert/length/meters-to-feet">Meters to Feet Converter</a>
by <a href="https://www.experttoolkit.net">ExpertToolkit</a>
</p>
<script async src="https://www.experttoolkit.net/embed.js?v=11"></script>Keep the small caption link — it is the only thing we ask in return for the free widget, and it sits in your page (not the iframe) so it reads as a normal credit line.
Customization parameters
| Parameter | Values | Description |
|---|---|---|
| theme | auto | light | dark | Color theme. auto follows the visitor's system setting. |
| accent | #hex | Accent color for the result and buttons. |
| radius | 0–24 | Corner radius in pixels. |
| bg | transparent | #hex | Card background. transparent blends into your page; a colour is used exactly as given, with text and inner surfaces re-derived from it so it stays readable. |
| textColor | #hex | Text colour. Kept, but darkened or lightened just enough to clear WCAG AA against the background. |
| borderColor | #hex | Outer card border colour. Used exactly as given. |
| inputBg | #hex | Background for inputs, panels and the result card. Text on it is contrast-checked separately from the card, so the controls stay readable. |
| inputBorderColor | #hex | Border colour for inputs, selects and panels. Used exactly as given. |
| surface | #hex | r,g,b | Safely tint the semantic palette toward the host page color. |
| hideBrand | true | false | Hide the “Powered by” attribution link. |
| allowUnitChange | true | false | Converter only — let visitors change units. |
| density | compact | comfortable | spacious | Shared spacing scale for the complete widget. |
| font | system | humanist | geometric | grotesk | rounded | serif | slab | condensed | mono | Locally-available font-stack preset; never downloads a font, so the widget adds no request to your page. |
| elevation | none | soft | strong | Outer-card shadow preset. |
| controls | outline | filled | minimal | Appearance shared by inputs, selects, and text areas. |
| resultStyle | highlight | subtle | plain | Visual emphasis of the result area. |
| scale | 85–125 | Typography scale in percent. |
| padding | 8–32 | Explicit widget padding in pixels. |
| borderWidth | 0–4 | Outer card border width in pixels. |
| controlRadius | 0–24 | Input, select, and text-area corner radius in pixels. |
| buttonStyle | rounded | pill | square | Shared action-button corner treatment. |
| resultAlign | auto | left | center | right | Alignment for the result area. |
| motion | normal | reduced | Disable non-essential widget motion when reduced. |
| contrast | standard | high | Use the standard or high-contrast semantic palette. |
| layout | auto | stacked | Responsive layout or force every primary section into one column. |
| resultSize | sm | md | lg | xl | How large the answer renders relative to the inputs. |
| labelCase | auto | normal | upper | Field-label casing. auto keeps each widget's own default; normal and upper apply to every widget. |
| surfaceStyle | flat | gradient | Flat card surface or a token-derived subtle gradient. |
License & attribution
- Free for personal and commercial sites.
- Keep the caption credit link that ships with the snippet — that is the deal for using the widget free. You may hide the in-widget badge with
hideBrand=true, but leave the caption. - Widgets run entirely in the visitor's browser — no tracking, no ads inside the frame.