We build the calculator. You put it on your site.

You tell us what your customers keep asking. We build a calculator that answers it, source every number in it, write a test suite for the maths, and host it. You paste one snippet into your page. It is the same engine that runs the 276 calculators on this site.

Two ways to do it

The build fee covers the actual work: the research, the sourcing, the building, the writing and the testing. The monthly covers hosting and, more importantly, keeping the figures current and the tests green as rates and rules change underneath them.

Those are the prices, not a starting point for a negotiation. A calculator that needs unusual source research, where somebody has to go and read a standard or a regulation before a line of code is written, is the one case we would quote separately, and we would say so before you committed rather than after.

Why sponsored is cheaper

Because we get something out of it. A sponsored calculator lives here as well as on your site, so it earns us traffic and gives us a page we own. That is worth real money to us, and it is fair to pass it back to you rather than charge you the same as somebody who wants us to build something and then never speak of it again.

If your calculator is the kind of thing the public would search for, sponsored is almost always the better deal. If it prices your own service, or embeds your own rate card, or would simply be strange sitting on a public calculator site, take the exclusive.

One thing we will not do

The link from a sponsored calculator to your site is marked rel="sponsored". That is Google's rule for any link that has been paid for, and we follow it.

So be clear about what the sponsored tier buys: brand placement in front of people already looking for the thing you sell, and the referral traffic that comes with it. It does not buy search ranking, and anyone who sells you a paid followed link is selling you something that can get both sites penalised. We would rather lose the sale than explain that later.

What you actually get

• Every number sourced. Not a figure copied off a competitor's page. If it comes from a standard, a regulation or a published table, we go and read the original and say on the page where it came from.
• A test suite. The maths is checked by executing it, not by eyeballing the output. Across this site that runs to more than 19,000 assertions, and yours joins them.
• The working shown. Your customers see how the answer was reached, which is what makes a calculator persuasive rather than merely present.
• It keeps working. When a rate changes or a rule moves, we update it. That is what the monthly is for.
• Mobile, dark mode and accessibility handled, because they are handled once in the engine rather than per calculator.

How it goes

1. You tell us the question your customers ask and what you already say back to them.
2. We come back with a scope, a fixed build fee inside the bands above, and what we think the honest version of the answer looks like. Sometimes that includes telling you the rule of thumb your industry uses does not survive checking.
3. We build it, source it and test it. You see it working before you pay the balance.
4. You paste one snippet. It works on any site, no plugin, no JavaScript conflicts.

If you just want a free one

Every calculator already on this site is free to embed, permanently, with no account and no fee. If one of the 276 already answers your customers' question, take it and go: the embed page has the snippet. This page is only for when the calculator you need does not exist yet.

Start a conversation

Email hello@calcaholic.com with the question your customers keep asking. You will get a straight answer about whether a calculator would help, what it would cost, and whether one of the free ones already does the job.