One HTML file you open in your browser. Works with no internet connection: no account, no wallet connection, no price feed, no tracking. It only does the maths on numbers you type in.

What's inside (4 tabs):

• Average Cost: enter your buys (price, quantity or amount spent, fee % or flat; fee added on top of amount). Shows weighted average price (excl. fees), cost basis per unit (incl. fees), break-even sell price after a sell fee, P/L at a price you type, and how much to buy to reach a target average (tells you when it's not possible).

• Position Size & Risk: balance, risk % or amount, entry, stop (price or %), long or short, optional target, leverage, fee per side. Fees are included by default so the loss at your stop equals the risk you chose; one click shows the textbook no-fee size. Shows size, notional, margin, loss at stop, gain at target, reward:risk and break-even hit rate. Warns when risk is above 2%. Wrong inputs (stop on the wrong side, zero distance, negatives) show a clear error instead of a number.

• Losing Streak: your balance after up to 100 losses in a row.

• DCA Plan: a weekly, every-2-weeks or monthly buy schedule using prices you type or paste (date,price); fee taken out of amount. It does not fetch or predict prices.

Also: formulas shown on every tab, numbers like 1,000 or 12,345.67 accepted, JSON backup/restore, CSV export, print / save as PDF, works at phone width.

Saving: your inputs are saved in this browser and the tool saves automatically as you work. For anything important, use "Download backup (JSON)" or "Export this tab (CSV)" regularly, since browser storage can be cleared.

Not included: liquidation price, live prices, tax calculations, wallet or account connections.

Tested: Chromium 156 and Firefox 157 on Linux (headless automation) at desktop (1280 px) and phone (390 px) widths; print to PDF in Chromium (Letter and A4).
Not tested: Safari (Mac/iPhone), Edge, real phones, Windows, macOS, real printers, private/incognito mode.

Files: offline-crypto-calculator-v1.1.zip -> crypto_calculator.html, README.txt

Disclaimer: Estimates from your inputs only. Not financial, investment or tax advice. Educational planning tool; it doesn't tell you what to trade and makes no promise of results. Trading crypto, especially with leverage, can lose you all of your money.