The ultimate free online tools for everyone. From Physics and Engineering to International Shopping and Home Living. Accurate, visual, and easy to use.
High-precision converters for academic and professional use.
m, ft, in, ly
kg, lbs, oz
°C, °F, K
L, gal, ml
m², acres
mph, km/h
J, cal, kWh
Pa, bar, psi
W, kW, hp
TB, GB, MB
N, lbf
N·m, lb·ft
Learn the history, science, and practical applications behind every unit conversion.
Calculate your revised salary under 8th Pay Commission (effective Jan 1, 2026). Use official fitment factor projections (1.83x-2.86x), HRA rates, and DA calculations to estimate your exact salary hike.
Calculate income tax for FY 2025-26 with official Budget 2025 slabs. Compare New Regime (₹12L tax-free) vs Old Regime (with deductions). Find out which regime saves you more money.
Fix upside-down or sideways PDFs permanently. Learn the difference between rotating view vs rotating pages and rotate PDFs correctly so they open properly everywhere.
Convert JPG, PNG, or HEIC images into a single PDF instantly. No watermarks, no file limits, and no sign-up required.
Learn how to merge PDF files securely without uploading them to a server. This guide explains client-side PDF merging, privacy risks, and the safest way to combine PDFs online.
Buying a press or calculating structural loads? 'Ton' is a dangerous word. Learn why pros use Kilonewtons (kN) and how to convert safely before you break your equipment.
Gas station pump says PSI, car door says Bar? Don't guess. We explain the difference, the magic 14.5 conversion, and why getting it wrong costs you fuel.
Your bike pump uses PSI, but the weather report uses hPa. Why? We explain the 'Dollar Bill' analogy and how to read a barometer to predict storms.
Stop guessing your size. A complete guide to international shoe sizing. Learn how to measure your feet correctly, convert Men's to Women's, and why Nike fits differently than Adidas.
Because unit conversion doesn't have to be boring!
Celsius vs Fahrenheit wars never end
"Europeans: It’s only 40°C, just a bit warm. Americans: Bro, that’s 104. I’m MELTING ☠️"
Every baker’s struggle with grams vs cups
"Chef: Add 200 grams of flour. Me: Okay, but how many coffee mugs is that? 🫠"
That dreadful SI unit moment
"Teacher: Show all unit conversions. Me: Shows vibes 😎"
Traveling between lbs and kgs feels illegal
"Me in the US: Benches 100 lbs 🇺🇸 Me in Europe: Benches 45 kg 🇪🇺 Also me: Wow, I got weaker crossing the ocean 💀"
Fuel efficiency makes no sense across borders
"American: 30 MPG is amazing! 🚗 European: 7 L/100km is amazing! ⛽ Me: Both are numbers. I walk now 🚶♂️"
Why unit conversions matter in real life
"NASA: We lost a $125M Mars orbiter 😭 Reason: Inches vs Centimeters. Earth: Bro rage quit over math 🤦♂️"
When Celsius people hear Americans talk weather
"American: It's 100 degrees today 🔥 European: BRO, you'd be vapor by now ☠️"
The eternal battle in school geometry
"Teacher: Draw a 10 cm line. Me: Whips out a 12-inch ruler. Brain: Divide by 2.54 real quick 😵"
Buying bananas should not require math
"Cashier: 2 kilos of apples please 🍎 Me: Uh… so that’s like… 4 footballs worth? 🏈"
The metric system is used by 95% of the world's population, making it the global standard for science and trade.
One inch equals exactly 2.54 centimeters. This definition was internationally agreed upon in 1959.
The Kelvin scale starts at absolute zero (-273.15°C), where all atomic thermal motion ceases.
A liter was originally defined as the volume of 1 kg of water at 4°C (maximum density).
One horsepower (745.7 watts) was coined by James Watt to compare steam engines to draft horses.
Standard atmospheric pressure (1 atm) is defined as 101.325 kPa at sea level.
