About CalcKit
From Spreadsheet to Single-Purpose Calculator
Most calculation questions are tiny. "What's 15% off $84.99?" "How much interest will I pay on a 5-year, 6% car loan?" "Is my BMI actually in a healthy range?" You could open a spreadsheet, type out the formula, and format the cell — or you could reach for a tool that already knows the formula and just wants your inputs.
A spreadsheet is a marvelous general-purpose instrument, but for a single answer it's overkill: you hunt for the right function, second-guess the parentheses, and then wonder if the result is in dollars or percent. Every calculator here does one job, shows the inputs it needs, and gives you the number. No formulas to remember, no cells to format.
45 Calculators, One Goal: Instant Answers
CalcKit ships 45 calculators and converters, organized the way people actually look for them:
Financial 💰
Mortgage, loan, and auto-loan calculators with full amortization; compound interest and savings-goal planners; investment ROI and inflation adjusters; plus salary, tip, discount, margin, and GST/VAT tools for everyday money questions.
Math 📐
Percentage, ratio, fraction, and GCD/LCM calculators; a scientific calculator for heavier expressions; a grade calculator for students; and standard deviation for quick stats.
Health & Fitness ❤️
BMI, body-fat, and calorie calculators, a running pace calculator, and a pregnancy due-date calculator.
Date & Time 📅
Age (in exact years/months/days), date difference, hours worked, time arithmetic, and working-days counters.
Everyday utilities 🛠️
A color converter (HEX/RGB/HSL), gas mileage, number-base converter, password generator, random number generator, and word counter.
Unit converters 🔁
Ten converters covering length, weight, temperature, area, volume, speed, data storage, energy, pressure, and fuel economy — plus a dynamic "X to Y" page for any pairing.
Formulas You Can Verify
A calculator that hides its math is a black box. CalcKit does the opposite: every tool shows the formula behind the answer, so you can sanity-check the result before you trust it. The mortgage calculator displays the standard amortization formula; the BMI tool shows weight / height²; the compound-interest tool breaks out principal, rate, compounding periods, and time so you can see which lever moves the number most.
This matters most for the questions where being wrong is expensive — a loan payment you didn't budget for, a savings target you'll miss, a unit conversion that throws off an entire recipe or engineering spec. When the formula is visible, a wrong answer is one you can catch.
Built for Bilingual Users
CalcKit ships in English and 简体中文 under parallel paths (/financial/... and /zh/financial/...), with hand-written copy on both sides. The Chinese site isn't a translation afterthought — calculator names, field labels, and result phrasing read naturally to a native speaker, and units follow local conventions (斤 vs. pounds, 摄氏 vs. Fahrenheit) where it makes sense.
Privacy by Design
The numbers you put into a salary calculator or a BMI tool are nobody's business but yours. CalcKit runs every calculation in your browser — there is no server endpoint that receives your inputs, no log of which calculator you opened or what you typed. The page loads once from a CDN; after that, your salary, your weight, and your loan balance stay on your device. See the privacy policy for the details.