Free online calculators & tools that just work
66 hand-built tools for money, business, dates, units, text, PDFs and images. Everything runs privately in your browser — no sign-up, no uploads, no limits.
Most popular tools
View all 66 tools →Loan Calculator
Find your monthly payment, total interest and payoff schedule for any fixed-rate loan.
Percentage Calculator
Solve any everyday percentage question: X% of Y, X is what % of Y, and more.
Merge PDF
Combine several PDF files into one document — privately, right in your browser.
Word Counter
Count words, characters, sentences and paragraphs — plus reading time and top keywords.
Age Calculator
Find exact age in years, months and days — plus a countdown to the next birthday.
Mortgage Calculator
Estimate your full monthly house payment including tax, insurance, PMI and HOA.
QR Code Generator
Create free QR codes for links, Wi-Fi, email, phone and text — they never expire.
Image Resizer
Resize photos to exact pixels or a percentage, keeping the aspect ratio.
BMI Calculator
Calculate adult body mass index in pounds/feet or kilograms/centimeters.
Compound Interest Calculator
See how savings and investments grow with compounding and regular contributions.
Password Generator
Generate strong, truly random passwords on your device — never sent anywhere.
Currency Converter
Convert between 160+ world currencies using daily-updated reference rates.
Browse by category
Finance Calculators
Work out loan payments, interest, savings and pay before you commit to a number.
- Loan Calculator
- Mortgage Calculator
- Auto Loan Calculator
- Compound Interest Calculator
- Simple Interest Calculator
Business & Shopping Calculators
Price products, check margins, split bills and work out percentages in seconds.
- Percentage Calculator
- Percentage Change Calculator
- Discount Calculator
- Sales Tax Calculator
- Tip Calculator
Health & Fitness Calculators
Quick, well-sourced estimates for BMI, daily calories and running pace.
All 3 health calculators →Date & Time Calculators
Count days, find dates, measure durations and convert time zones accurately.
- Age Calculator
- Days Between Dates Calculator
- Add Days to Date Calculator
- Business Days Calculator
- Time Duration Calculator
Unit Converters
Convert between metric, imperial and US units — and see every unit at once.
All 12 converters →Text Tools
Count, clean, convert and format text instantly — your text never leaves your browser.
All 11 text tools →PDF & Image Tools
Merge and split PDFs, and resize, compress or convert images — without uploading files.
All 6 PDF & image tools →Web & Utility Tools
Generate QR codes and passwords, pick random winners and tidy up web data.
- QR Code Generator
- Password Generator
- Random Number Generator
- List Randomizer & Name Picker
- JSON Formatter & Validator
Why people use ToolsKingMaster
It solves the task in one step. Each tool does one job properly — a loan calculator shows your payment, total interest and payoff schedule; the PDF merger hands you a single file. You don't need to install software or learn a spreadsheet formula.
It is private by design. Calculations and file processing happen on your own device. Your PDFs, images and text are never uploaded to our servers, which also makes the tools fast even on a slow connection.
It explains the answer. Every tool page shows the formula it uses, a worked example and answers to common questions, so you can check the result and understand what it means before you make a decision.
What you can do here
Plan a purchase with the mortgage, auto loan and compound interest calculators. Price products with the margin, markup and sales tax tools. Count days between dates, convert units, clean up text, merge PDFs or resize photos for a form — all free, on any phone, tablet or computer.