About
CryptoFumble answers one question: what would your money be worth today if you'd bought, sold, or slowly stacked a coin at some point in the past? Pick a coin, an amount, and a date — it does the math against real historical prices. Sometimes the answer is thrilling. Usually it's a little painful. That's the point.
It's for fun and reflection, not investment advice. It shows a hypothetical outcome based on historical prices — never a prediction, never a recommendation. Crypto is volatile and you can lose money. Always do your own research before investing anything.
Start with one of ten ready-made crypto moments, from Bitcoin Pizza to market crashes and missed opportunities, or choose “Calculate your purchase” and enter your own coin, amount, month, and year. The result uses the same historical-price engine as the main calculator.
Every calculation can become a CryptoFumble receipt or Fumble Card: a compact visual with the important numbers, the outcome, and a little personality. You can save it or share it with a friend through the options available on your device. A duel uses the same easy sharing flow: one date, equal virtual budgets, different coins.
The site also has five quick games that use virtual money and real historical prices (Sell or hold, Fumble roulette, What happens next, Time machine, and The decision court), plus shareable takes on your own decisions: a playful portfolio roast, a check on whether you sold too early or on time, and a crypto-year recap. There is also an anonymous running tally of what other players chose.
The calculator is for “what if” scenarios. “My Portfolio” is for what actually happened: record purchases and sales or import compatible trade history, then follow live profit or loss, average cost, and each coin's contribution to the total. Portfolio memories and “HODL vs reality” turn that history into understandable moments instead of another spreadsheet. Portfolio data stays in your browser unless you deliberately connect an optional server feature.
Connect your portfolio to @CryptoFumble_bot — one button on the site, one code sent to the bot, no separate account — and it sends a weekly digest straight to Telegram: how your portfolio moved, without you having to open the site to check. The bot can also run a calculation right inside the chat with /calc <coin> <amount> <year-month>, e.g. /calc btc 100 2020-01.
Turn on notifications and get pinged the moment one of the major coins hits a new all-time high. Install CryptoFumble on your phone as an app (there's a one-tap prompt for it) if you'd rather have an icon than a bookmark. And if you send someone your link, the site quietly counts how many people came through it — no account needed on either end.
CryptoFumble is an independent, one-person side project — not a company, not a fund, not a trading desk. It started from wanting to know exactly how much money past self left on the table, and turned into a small tool other people seem to enjoy torturing themselves with too.
Live and historical prices come from CoinGecko, through a caching proxy so the site isn't hammering their API directly. If that's briefly unreachable, the calculator falls back to an approximate historical dataset for a handful of major coins — always clearly labeled "OFFLINE DEMO DATA" right on the result, so you know exactly what you're looking at. Numbers are rounded and illustrative; they won't match a trading terminal to the cent.
The calculator is free and will stay that way — no subscription, no paywalled export, no cap on how many times you can use it. If you liked it, there is an optional direct crypto donation. After some results, “Next Move” may also show locally relevant platforms. Those buttons are affiliate links: CryptoFumble may earn a commission if you sign up through one, at no extra cost to you. They are optional, clearly marked, and are not recommendations or instructions to trade.
Email r26061980@gmail.com, follow @CryptoFumbleCom on X, or join the CryptoFumble Telegram channel. Bug reports and "you should really add..." ideas are both welcome.