About SaaS Tools UK

Why I built this

I'm a software developer based in the UK. This site started because I kept rebuilding the same spreadsheet.

Every time I wanted to answer a simple question — how long does the money last if nothing changes? — I'd end up in a tangle of cells, half-remembered formulas, and a nagging worry that I'd mistyped something in row 40 and wouldn't notice. The accounting software I had access to could produce beautiful reports about last quarter, but was oddly bad at answering a straightforward forward-looking question in under a minute.

So I built a page that does exactly that one thing, and nothing else. No sign-up, no trial, no dashboard to configure. Type in three numbers, get an answer. It turned out other people wanted the same thing, so I kept adding to it.

How the calculations work

There's no magic here, and I think it's worth being upfront about that. The calculators use standard, widely accepted formulas — net burn is monthly expenses minus monthly revenue, runway is cash divided by net burn. You can verify every number by hand.

Everything runs in your browser using plain JavaScript. Nothing you type is sent to a server, stored, or logged, because there's no server-side processing at all — the page you've downloaded does the arithmetic locally. That's a deliberate design decision: the numbers people put into a runway calculator are often the most sensitive figures in their business, and the safest way to handle sensitive data is not to receive it in the first place.

The trade-off is that the tools are deliberately simple. They won't model seasonality, deferred revenue recognition, or a complex cap table. For those you need a real financial model and probably an accountant. What these do is give you a fast, accurate answer to a simple question, which is often the thing you actually need at 11pm when you're trying to decide whether you can afford a hire.

Where the guidance comes from

The written guides on this site draw on published sources and UK government guidance rather than opinion. Where I cite a figure — HMRC's R&D tax credit rates, Companies House fees, David Sacks' burn multiple benchmarks — it comes from the original source, and each guide links to it so you can check. Where something is convention rather than a hard rule, like the 12-to-18 month runway buffer, I try to say so plainly.

Rates and thresholds change, particularly the tax reliefs. I review the guides periodically, but if you spot something that's gone out of date, please tell me and I'll correct it.

Honest limits

I'm a developer, not an accountant or a financial adviser, and this site isn't regulated financial advice. It's a set of calculators and some plain-English explanation of concepts that are genuinely useful to understand. For decisions that actually matter — a funding round, a redundancy, a tax filing — talk to a qualified professional who knows your specific situation. The full disclaimer is here.

How it stays free

The site is funded by advertising, which is why you'll see ads on these pages. That's the whole business model — there's no paid tier, no email list, and nothing is upsold to you. How advertising cookies work here is set out in the privacy policy.

If you've found the tools useful, or something is broken, or there's a calculator you wish existed, the contact page comes straight to me. Suggestions from people actually using the tools are where most of the additions have come from.