Widget platforms rent you a calculator for $5–200 per month, count your visitors, and — their own FAQ says so — disable it two days after you exceed the quota. This kit is one embed script and twenty editable calculator templates that run entirely on your pages, localize numbers and currency per market, and send leads only to the webhook you choose. $59 once — no quotas, no subscription.
Get the kit — $59This is the actual calculator.js from the kit, rendering inside a Shadow DOM on this page. The full demo with four templates and an EN/DE/TH switcher: open the live demo.
One zip: the embed engine, twenty calculator templates, the theme tokens, the platform playbook and the lead-capture SOP — plain files you own, with nothing to log into.
calculator.js is a single vanilla-JS file with no build step. It renders each calculator inside a Shadow DOM, so your site's CSS cannot break the widget and the widget cannot break your site. Everything computes in the visitor's browser.
Price quote, product price, shipping rates, mortgage, loan annuity, BMI, car rental, solar savings, moving service, configurator, ROI, savings growth, print cost, cleaning, catering, venue, day rate, renovation, quantity tiers, HVAC — each one a JSON file you edit, not a locked widget.
The browser's own Intl.NumberFormat renders 1.234,56 € for German visitors and $1,234.56 for American ones. Currency and units are per-locale settings; the solar, quoting and loan templates ship with full English + German (+ Thai) labels.
The formula language is plain arithmetic with nested ifs, comparisons and ten functions — the same function set the big widget platforms expose. A safe parser runs it; rate tables, price tiers and annuities are each demonstrated in a shipped template.
Flip the CTA to webhook and a small form (name, email, honeypot included) POSTs the visitor's exact configuration and quote to your Zapier, Make, n8n, Google Sheet or your own endpoint. No consent-banner dependency: the widget sets no cookies and stores nothing.
Embed recipes for WordPress, Ghost, Shopify and static HTML (with the two known gotchas), the formula reference, localization guide, theming tokens, a QA checklist — and the 20-minute webhook setup plus the weekly check that keeps your pipeline alive.
No hosted builder. Deliberately. The big platforms have AI builders and drag-and-drop editors — rented monthly, with your calculators and leads living on their infrastructure. This kit is the other deal: files on your server, no account, no meter, and nobody who can switch your calculator off on your own website.
No dashboard, no outcome promises. A calculator shows visitors a number — whether that number becomes a signed contract depends on your service and your follow-up, not on the widget. What the kit maximizes is what you control: a quote your visitors can get in thirty seconds, in their language and currency, with leads landing in your systems.
Estimates stay estimates. The loan, mortgage, solar, savings, BMI and HVAC templates ship with disclaimers rendered in a highlighted box. Keep them — an honest "estimate only" line is part of the product, not an obstacle.
About ten minutes to your first calculator on your own site; the whole customization pass about thirty.
Serve the folder, open demo.html, and try four templates live with a language switcher. Each of the twenty demonstrates one formula technique — rate tables, tiers, annuities, gross-ups — so you edit the closest one instead of starting from zero.
Upload calculator.js and the templates to any path on your site, then paste a div and a script tag — a WordPress Custom HTML block, Ghost code injection, a Shopify Custom Liquid section, or plain HTML. The playbook has each recipe written out.
Edit the JSON: your prices and labels, your market's currency and units, your theme colors. Flip the CTA to webhook when you want the leads; the SOP walks the endpoint setup in about twenty minutes.
Published pricing of the widget-calculator category, checked 2026-09-20. Every platform below meters something — impressions, visits or leads per month.
| Tool | Published price | What is metered | When you exceed it |
|---|---|---|---|
| Calconic | $5–44/mo billed annually (Light 10 calcs / 3,000 impressions · Regular $14 / 15,000 · Bold $44 / 75,000); free plan 500 impressions | impressions per month | plan limits — widget stops at the quota |
| ConvertCalculator | $20–200/mo (Hobby 2,000 visits · Pro $40 / 10,000 visits + 30 payments · Platinum 300,000) | visits per month | its own FAQ: “We disable your calculators 2 days after you passed your monthly visit limit” |
| Outgrow | $14–720/mo (Freelancer 5 pieces / 250 leads · Business $600/yr or $720 monthly / 50,000 leads); done-for-you builds from $250 per piece | leads per month | plan limits — or pay them $250+ to build it for you |
| Calculator Widget Kit | $59 once — no subscription | nothing — files on your server, unlimited use | nothing can time out: no account, no meter, no one to switch it off |
Competitor figures are their published prices (calconic.com/pricing, convertcalculator.com/pricing, outgrow.co/pricing — including their quoted “disable after quota” policy and $250 done-for-you builds), verified 2026-09-20; subscriptions change often, check before you buy anything. That self-hosting calculators is a real need shows elsewhere too: the two most-installed WordPress calculator plugins report 20,000+ and 40,000+ active installs (wordpress.org API, 2026-09-20). This kit is a one-time purchase — no meter exists that could be exceeded.
No monthly plan, no impression counter, no per-lead fee — the platforms already charge enough of those.
≈ ฿2,090
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No — there is no dashboard to log into and nothing to renew. You get files: one embed script (calculator.js, vanilla JS, no dependencies) and twenty editable JSON templates. They run on your server, under your domain, with no quota that could ever be exceeded — because no meter exists.
Anywhere you can paste HTML: WordPress (Custom HTML block), Ghost (code injection), Shopify (Custom Liquid section), Webflow/Framer/Squarespace embeds, and static sites (Astro, Hugo, Eleventy, plain HTML). Upload calculator.js and the templates once, then a div + a script tag per calculator. The playbook writes out each recipe, including the two known gotchas (cache plugins on WordPress, JSON assets on Shopify).
No. Editing a calculator means editing JSON: labels, default values, your prices. The formula language is plain arithmetic with nested if() and ten functions (min, max, sum, round…) — every one of the twenty templates demonstrates a technique, so you adapt the closest one rather than writing from scratch. A full reference and a troubleshooting table are in the playbook.
Yes — optionally. Flip the CTA to webhook and a compact form (name, email, optional phone/message, honeypot against bots) POSTs the visitor's exact configuration plus the computed quote to an endpoint you own: Zapier, Make, n8n, a Google Sheet or your own ten-line handler. The SOP includes all three recipes and a weekly five-minute check. The calculator itself sets no cookies, stores nothing, and contacts no third party — leads never touch our infrastructure because there is none involved.
They are good builders — and they meter. Published plans run $5–200 per month with impression, visit or lead quotas, and one provider documents in its own FAQ that it disables your calculators two days after you pass the monthly limit. Done-for-you builds start around $250 per piece. This kit is $59 once: twenty templates, localized, on your domain, with no quota to exceed and no vendor in between you and your leads.
If the kit doesn't fit how you work, write to us within 14 days of purchase and we refund in full — the files are yours to keep or delete. One refund per purchase; we only ask for optional feedback.
$59 one-time · ≈ ฿2,090 · free updates v1.x · instant download
Get the Calculator Widget Kit — $59