CalculatorFox
Free online and embeddable calculators with step-by-step workings and cited sources.
Analytics·Productivity·Finance
About
CalculatorFox provides access to over 1,336 free online calculators across categories ranging from finance and business to health, math, and everyday tools. Every calculator features step-by-step calculations and cited sources, showing users how results are worked out live as figures change. No account is needed for basic use.
Designed for individuals and businesses alike, the platform allows users to save scenarios, compare results side by side, and export data. For publishers and advisers, CalculatorFox offers an embeddable tool that requires only three lines of code. Businesses can update shared figures in one central account without editing HTML, allowing all embedded calculators across different web pages to stay synchronized automatically.
What makes CalculatorFox different is its focus on transparency, verifiable sources, and seamless embedding capabilities. Free to use, the platform offers paid plans for users who want to save personal scenarios or present client reports and customized rates under their own brand.
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FounderPlaybooks.
What other founders did to grow.
2722 dispatches from hundreds of founders, pulled from the week's best podcasts.
Somewhere between 80 and 85% of revenue still to this day comes from advertising. What the ads allow us to do is to also be available and support markets that would not traditionally have subscription apps or use in-app purchases — Tier 2, Tier 3 — where most other big brands would not advertise.
80-85% of Subway Surfers revenue comes from ads — rewarded video lets users pay with attention, opening Tier 2/3 markets subscriptions can't reach
Subway Surfers' massive global download share in lower-GDP markets is enabled by ad monetization — markets where $10/month subscriptions represent real economic friction but watching an ad costs nothing. For subscription apps looking to grow internationally, rewarded video and interstitial ads offer a genuine monetization path in markets where subscription conversion is structurally low, allowing reach without sacrificing the premium tier in high-income markets.
most advertisers are asking for age and gender of users which is super helpful because meta always reports you their data on age and gender level and if you then in your product also apply that level again then you can basically cross check and look into I don't know I'm seeing in my app that age group 45 to 54 is 5X more valuable
Ask age and gender in onboarding to build a channel-quality model without user-level tracking
Without user-level attribution, the only way to understand channel quality is through demographic cross-referencing. By collecting age and gender in onboarding, Burke can compare in-product LTV by cohort against the same breakdown from Meta's ad reporting. If 45-54s are 5x more valuable in product but Meta charges only a 2x premium to reach them, that is a clear bidding signal.
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