About Us

Last updated: 14 September 2026

Kit Space is a free library of online calculators and the written guides that explain them. There
are hundreds of working calculators here, grouped into broad areas — Finance,
Business & Trade, Lifestyle, Legal, Environment, and Gaming — alongside the long-form
guides that show the arithmetic behind the most-used ones. Nothing here requires an account, and
nothing is held back behind a paywall or a “pro” tier.

The short version: Kit Space publishes the arithmetic and the assumptions behind
it. It does not publish advice. A calculator can tell you what a set of numbers produces; it cannot
tell you whether those numbers describe your situation, and it is not a substitute for a qualified
professional where the stakes are high.

Who runs Kit Space

Kit Space is an independent publication, written and maintained by one person. There is no editorial
board behind the byline, no outsourced content desk, and no agency operating the site on someone
else’s behalf.

  • Editor: Owen Renshaw, founder and editor. Owen writes the guides, builds and reviews the calculators, and answers the corrections inbox personally.
  • Corrections and enquiries: [email protected]
  • Editorial desk hours: Monday to Friday, 09:00–18:00 (UTC+8)
  • How to reach us: see the Contact page

We work in English and French. Every calculator and guide is published in both languages, and the
French edition is written for French readers rather than produced by pushing the English text
through a translator and publishing whatever comes out.

How the calculators and guides are built

A calculator is only worth using if the formula behind it is right and the reference values it
relies on are current. That is where nearly all of the work goes, and it follows five rules:

  1. The formula is printed on the page. Every guide states the equation it uses, so you can follow the arithmetic yourself instead of taking the output on faith. If you can reproduce the result by hand from the formula shown, the tool is doing what it claims to do.
  2. External figures are attributed. Tax brackets, statutory limits and thresholds, contribution ceilings, interest-rate benchmarks, emissions factors, exposure and safety limits, food-safety times — these are not ours to invent. They are set by governments, regulators, and standards bodies, they change without notice, and they differ from country to country. Where a page depends on one, it names the source and says when it was last checked.
  3. Guides are built around worked examples. The long-form guides exist so that you can see the calculation performed once, with real numbers, before you run your own. They are not filler between two ad blocks.
  4. Every page carries a date. All pages on this site show when they were last reviewed. A page that has not been reviewed recently says so, and that is a signal worth taking seriously.
  5. Corrections override everything else. When someone reports an error and we can confirm it against the source, the tool and the guide are fixed and the page is re-dated. Where a figure cannot be confirmed, the page is changed to say that the number is an estimate.

What Kit Space is not

Kit Space is not an advisory service, and it is not a substitute for one. We are not a licensed
financial adviser, broker-dealer, accountant, tax preparer, attorney, or physician, and no one who
works on this site holds themselves out as one. No adviser-client, attorney-client, accountant-client,
or physician-patient relationship arises from your use of this website.

Every calculator on this site returns a number that follows from the inputs you type in. It does not
know whether those inputs are right, whether they apply to you, or whether the scenario you are
modelling is one you should be in. That judgment is yours, and where the stakes are high it belongs
with a qualified professional in your own jurisdiction. The full statement is on our
Disclaimer page.

How Kit Space is funded

Kit Space is free to use and is supported by display advertising, including advertising served
through Google AdSense. That is the whole business model — there is no subscription, no paid
tool tier, and no charge for anything on the site.

Advertising does not reach into the calculators. Advertisers cannot change a formula, commission a
result, or buy their way into a recommendation, and no tool on this site has been created or
altered in exchange for payment. We do not accept sponsored calculators or paid rankings.

If we ever use an affiliate link, it is labelled as one on the page where it appears, and it never
changes the number a calculator returns. You can read how advertising cookies work on this site in
our Privacy Policy.

Corrections policy

If something on this site is wrong, we want to know, and we would rather hear it from you than
discover it later. Email [email protected] with:

  • the page URL;
  • the numbers you entered;
  • the result you expected, and why;
  • the result the tool actually returned.

That is usually enough for us to reproduce the problem in one pass. We check the report against the
source cited on the page. If the page is wrong, we fix the tool and the guide and re-date the page.
If the page is right and the wording misled you, we fix the wording, because that is a defect too.
If we cannot confirm the figure, the page stops presenting it as a fact and starts calling it an
estimate.

What is on the site

The library covers everyday money questions, small-business arithmetic, kitchen and household
ratios, legal cost estimators, carbon and energy maths, and game-mechanics modelling.
Representative examples from each area:

Finance

Retirement and tax modelling, investment return maths, loan and interest schedules, business
valuation, and personal balance-sheet arithmetic.

Examples: APR Calculator, APY Calculator, 1099 Tax Calculator, Bonus After Tax
Calculator, Book Value Per Share Calculator, Break-Even Inflation Rate Calculator, After-Fee Return
Calculator.

Business & Trade

Revenue and unit economics, pricing and elasticity, marketing and funnel metrics, payroll and
staffing ratios, inventory and cash-conversion maths.

Examples: ARR (Annual Recurring Revenue) Calculator, Average Order Value Growth
Calculator, Affiliate Commission Calculator, Beverage Pour Cost Calculator, Bounce Rate Calculator,
Buyer Price Elasticity Tool, Cash Conversion Cycle Calculator.

Lifestyle

Cooking and baking ratios, home and household planning, pet and family timelines, hobby and
crafting projects.

Examples: Bread Hydration Calculator, Baking Temperature Calculator, Cookie Yield
Estimator, Curry Spice Ratio Calculator, Budget Meal Planner, Companion Planting Chart Tool,
Anniversary Calculator.

Legal

Cost and fee estimators for common legal processes, compliance and record-keeping obligations,
estate and executor arithmetic.

Examples: Arbitration Cost Estimator, Commercial Arbitration Fee Calculator, Deposition
Cost Estimator, Estate Executor Fee Calculator, Data Retention Compliance Cost Calculator, Expert
Witness Fee Estimator.

Environment

Carbon accounting, transport and energy emissions comparisons, waste and recycling maths,
sustainability programme costing.

Examples: CO2 Absorption Rate Calculator, Bicycle vs Car Emissions Calculator, Bus vs
Car Carbon Footprint Calculator, Decarbonization Roadmap Cost Calculator, E-Waste Recycling Value
Calculator, Ecological Footprint Calculator.

Gaming

Probability and drop-rate maths, build and gear optimisation, progression and ranking models for
role-playing and strategy games.

Examples: Card Draw Probability Calculator, Drop Rate Comparison Calculator, Item
Enchant Success Rate Calculator, Defense vs Offense Build Calculator, Guild Ranking Point
Calculator.

Use the output as an input to your own judgment

The single most useful thing on this page is this: what you get out of a Kit Space
calculator depends entirely on what you put in. We do not verify your inputs, we do not
know your circumstances, and we do not check whether the scenario you are testing is realistic. If
the numbers you enter are wrong, or out of date, or belong to a different country’s rules, the
result will be wrong even though the arithmetic on the page is correct.

So treat every result as a working figure, not a verdict. Check it against a second source. Read the
assumptions printed on the page. And where the answer actually matters — a tax position, a
contract, a medical measurement — take it to someone qualified in your own jurisdiction.

Keep us honest

Kit Space gets better when readers tell us what is broken, unclear, or missing. If you spot an error,
send it to [email protected]. If a calculation you need
is not on the site yet, tell us that too — we add tools based on what people actually ask for,
not on what looks good in a keyword list.