All Calculators and Converters — One Privacy-First Tool Directory

Free easy online calculator: add, subtract, multiply, divide, percent and sign toggle, with keyboard input and big thousand-separated display, instant and local.

Trig/log/exp/factorial with parentheses, DEG/RAD, inverse (2nd) functions, live result and full keyboard input — instant and local.

Convert between hexadecimal, decimal, octal and binary instantly — choose input base, type, see all four readouts, fully local.

Enter values to get count, sum, mean, population and sample standard deviation, min and max — instant and private.

Plot multiple 2D functions with pan/zoom, numerical derivatives and tangent lines — SVG, instant and local.

Render 3D surfaces, parametric curves and point clouds in interactive WebGL with orbit controls — all local.

Numerically solve f(x)=0 over an interval and linear systems up to 6×6 — instant and private.

Matrix add/mul/transpose/inverse/determinant/RREF/rank/LU/eigenvalues up to 6×6, all in your browser.

Write sandboxed scripts with variables, functions, loops, arrays and plot commands — Ctrl/Cmd+Enter, all local.

Enter loan amount, rate and term to get your monthly payment, total interest, full schedule and charts. Try early-repayment scenarios side by side.

Monthly PIT withholding, separate vs combined bonus tax, and VAT in/out conversion — all with the active tax bracket highlighted.

Instant monthly payment, total interest and total cost for both equal-installment and equal-principal structures, with a downloadable schedule.

Solve any TVM variable from the other four, with end/begin annuity and payments per year — instant and local.

Enter a cash-flow series and discount rate to compute NPV and IRR instantly — add/remove flows, all local.

Generate SL/SYD/DDB depreciation tables from cost, salvage and life — yearly, accumulated and book value, local.

From millimeters to kilometers, inches to nautical miles and chi to meters — type once and see every length unit at once.

From milligrams to tonnes, pounds to carats and jin to liang, one input shows every weight equivalent instantly.

From square millimeters to square kilometers, mu to acres and square feet to square miles — enter once, see every area unit.

US vs UK gallons clearly separated. From milliliters to cubic meters, fluid ounces to cups, one input shows all volume units.

Convert Celsius and Fahrenheit instantly with Kelvin, Réaumur and Rankine shown alongside — no simple-multiplier errors.

From meters per second to light speed, km/h to mph and knots to Mach — one input shows every speed unit simultaneously.

Enter height and weight for an instant BMI with WHO classification and healthy weight range, metric or imperial.

Estimate BMR with Mifflin–St Jeor, multiply by an activity factor for TDEE, with Harris–Benedict comparison.

Estimate body fat percentage, fat mass and lean mass from neck, waist and hip measurements, men and women.

Divide waist by hip to get WHR and a WHO-based low/moderate/high risk rating for men and women.

Get your daily calorie target for fat loss, maintenance or muscle gain, plus a realistic goal timeline.

Turn a calorie target into grams of protein, carbs and fat with four presets or custom ratios and a donut chart.

Estimate how much water to drink daily from weight, activity and climate, shown in ml, L, fl oz and cups.