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All-in-one conversion suiteUnit Converters
86+ unit conversion tools for engineering, science and daily life
File Converters
70 browser-based image, PDF, audio, video, OCR & AI tools
Currency Converter
Live exchange rates for 75+ currencies
Crypto Converter
Real-time BTC, ETH, SOL + top 100
Solar Engineering
36 professional IEC/IS calculators
Engineering Calculators
Civil, mechanical and electrical design tools
Financial Calculators
EMI, SIP, FD, GST, income tax and retirement planning
Scientific Calculators
Physics, chemistry and maths utilities
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Popular toolsWhy OneCalc?
Built for speed, privacy and precisionFast Browser Processing
WebAssembly engines convert in milliseconds — no server round trips.
No Upload Required
Image, PDF and media tools process locally; files never leave your device.
Secure by Design
No accounts, no tracking pixels, no file retention.
Mobile Friendly
Every tool is touch-optimised and works on any screen size.
Engineering Grade
IEC and IS standard formulas with steps, assumptions and warnings.
Instant Results
Live calculation as you type, with copy, print and PDF export.
Free Forever
Unlimited use, no watermarks, no paywalls, no sign-up.
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Latest Articles
Guides & tutorialsHow to Convert PDF to JPG
Export crisp page images at the right DPI, in the browser.
Read guide SolarSolar Panel Size Guide
Size a PV array from monthly consumption, PSH and performance ratio.
Read guide FinanceUnderstanding Currency Exchange
How mid-market rates work and why they move during the day.
Read guide UnitsEngineering Unit Conversion Guide
SI base units, derived units and avoiding conversion mistakes.
Read guide ElectricalCable Sizing Tutorial
Voltage drop, current capacity and IS/IEC derating explained.
Read guideFrequently Asked Questions
12 answersGet calculator updates
New converters, engineering calculators and product updates — occasional emails, no spam.