bf-12c RPN Calculator

An RPN financial calculator with the classic 12c keyboard, 34 significant digits, and a green-screen display. Loans, mortgages, NPV, IRR, amortization, bonds, depreciation, dates, statistics and keystroke programs, the way the 12c does them.

Landscape is the full 4 by 10 keyboard: gold f legends above, blue g legends below, and the tall ENTER key. Portrait folds that keyboard in half, financial keys on top and the number pad where your thumbs are.

TIME VALUE OF MONEY
• n, i, PV, PMT and FV: solve for any one of them. Loan and mortgage payments, savings goals, lease rates, interest rates.
• Begin or end mode, and multiply or divide by 12 for monthly periods.
• Amortization schedules and simple interest.

CASH FLOWS, BONDS, DEPRECIATION
• Net present value and internal rate of return, with CF0, CFj, and Nj for up to 20 cash flow groups.
• Bond price and yield to maturity.
• Straight-line, sum-of-the-years-digits, and declining-balance depreciation.
• Dates and the days between them, in day-month-year or month-day-year.

THE STACK
• Real RPN with four levels, X Y Z T, plus LSTx. Stack lift follows the classic rules.
• Every register holds 34 significant digits, not floating point. f EEX shows all of them, f 0 to f 9 sets fixed decimals, f . sets scientific notation.
• Continuous memory: the stack, the registers and your program survive restarts.

MATH AND STATISTICS
• Percent, percent change, and percent of total. Mean, standard deviation, weighted mean, linear estimate, and correlation.
• Twenty storage registers with storage arithmetic. y to the x, square root, e to the x, natural log, factorial, fraction, integer, round.

PROGRAMS
• f P/R opens program mode: 99 merged lines, GTO, x<=y, x=0, R/S, pause, and single-step in both directions.
• The listing shows the classic keycodes and a readable mnemonic beside them.

ON THE GLASS
• Swipe the display left to backspace. Long-press copies X. Double-tap pastes, and paste understands 1,234.50, $1,000, (250.00) and 6.02e23.
• Four phosphor themes: P1 green, P3 amber, ice, and a classic 12c LCD.
• The MENU key (the 12c's ON key) opens the system menu: themes, haptics, a built-in manual and FAQ, first-run tips, sharing, rating, and a link to report a bug or ask for a feature. It never nags you to rate or share.

EVERY SCREEN
• Phones, tablets, foldables and Chromebooks, in split screen or a resizable window. The layout follows the window, and tablets print everything bigger.
• No touchscreen needed: click with a mouse or trackpad, or type on a hardware keyboard (digits, + − * /, Enter, Backspace, F1 for the menu).
• TalkBack reads every key in words and announces each result.

NO NONSENSE
Free. No ads. No network access. No tracking, no analytics, no permissions, and nothing is backed up off the device. Requires Android 13 or newer.

bf-12c is an independent fan project, not affiliated with or endorsed by any calculator maker.

If you learned finance on a 12c, or you're learning it now, this one is for you. Install it and press MENU.