Have you ever tried to figure out how much alcohol to buy for a wedding? Or what your freelance day rate should be? Or whether its cheaper to buy or rent?
I kept running into these boring math problems - not hard, but tedious enough that Id open a spreadsheet, fumble with formulas, and waste 20 minutes on what should take 30 seconds.
So I built boring-math.com - 125 free calculators for the everyday math nobody wants to do by hand.
Whats in there
The calculators cover everything from personal finance to party planning:
Money stuff:
- Compound interest calculator - see how your savings grow over time
- Buy vs Rent calculator - the actual math behind the biggest financial decision most people make
- Freelance day rate calculator - convert salary to day rate accounting for tax holidays and pension
- Savings goal calculator - how much to save monthly to hit your target
Life stuff:
- Wedding alcohol calculator - dont run out, dont overbuy
- BBQ calculator - meat per person, sides, the works
- Baby cost calculator - the real first year costs
Health and utility:
And about 110 more.
The tech
Built with Astro + Preact + Tailwind CSS. Static site deployed on Cloudflare Pages.
Each calculator is a single .astro page with an interactive Preact component for the actual calculation. No backend, no database, no accounts. Just math.
Why Astro? Perfect for content-heavy sites with islands of interactivity. The calculators need JavaScript but the surrounding content - explanations, FAQs, related links - is pure HTML. Astros island architecture means you only ship JS where you need it.
Performance: Lighthouse 90+ across all pages, local fonts, lazy-loaded interactive components.
What I learned building 125 of these
1. Every calculator needs context, not just inputs.
A compound interest calculator with just the math is boring. But add a worked example showing what happens if you start 5 years earlier? Now its useful content that Google actually wants to rank.
2. Related calculators create rabbit holes.
Someone using the savings goal calculator probably also wants the compound interest calculator. Internal linking between related tools keeps people on the site and helps SEO.
3. Schema markup matters.
Every calculator has WebApplication + FAQ + BreadcrumbList structured data. Tedious to set up but Google Search Console immediately started showing richer impressions.
4. The long tail is real.
Nobodys outranking the big sites for mortgage calculator. But additional dwelling supplement calculator Scotland? Those niches have real search volume and almost no competition.
Try it out
The whole thing is free, no sign-up required: boring-math.com
If youve got a calculator idea I havent built yet, drop it in the comments - always looking for the next piece of boring math to automate.
Top comments (1)
Really interesting tool — thank you!