Is OneCalcApp free to use?

Calculators and converters are free without mandatory sign-up. OneCalcApp AI chat and explanations use prepaid credits. Buy credits once and use them as needed, without a monthly subscription. Charges depend on token usage; ordinary tools remain free.

Are my files uploaded to a server?

No. Image, PDF, audio, video, archive, QR and OCR tools run entirely client-side using WebAssembly, so your files never leave your device.

How accurate are the unit conversions?

Conversions use exact SI base-unit factors and full double precision, so results match international standards to the displayed precision.

Where do currency rates come from?

Live exchange rates are fetched from a public rates API and refreshed regularly. The last update time is shown on the currency converter page.

Are the solar calculators engineering-grade?

Yes. All 36 solar calculators follow IEC and IS standard formulas and show the equation, step-by-step working, assumptions, warnings and design tips.

Can I use OneCalcApp offline?

Most unit converters and calculators work offline once the page has loaded. Currency rates and some AI tools require a connection.

Does OneCalcApp work on mobile?

Yes. Every page is fully responsive and touch-optimised, from the search bar to the engineering report exports.

Can I export or share results?

Calculators support copy, print, PDF report download and shareable links. File tools support individual downloads or a single ZIP.

Do I need an account?

No account is required. Favourites and recent conversions are stored locally in your browser only.

Which file formats are supported?

70+ tools cover images (JPG, PNG, WebP, HEIC, SVG), documents (PDF, Word, Excel, PowerPoint), audio, video, archives, QR/barcodes and OCR.

How can I request a new calculator?

Send a request through the contact link in the footer — new engineering, financial and scientific calculators are added regularly.

OneCalcApp – Free Online Calculators & Unit Converters

Ask OneCalcApp AI

Type your calculation, conversion, question or upload a file.

OneCalcApp AICalculator + ConverterFree tools · AI credits

Ask here. OneCalcApp AI collects missing inputs and uses verified internal calculator engines.

What can I help you calculate?

Ask a question, run a calculation, or find the right tool.

Up to 200 credits reserved per request; only actual usage is charged. A lower-cost model may be used when your balance is low. How credits work

Try these examples

View all examples

Explore Calculators

Professional engineering, financial, scientific and daily-use calculators.

Unit Converters

16 Calculators

Length, weight, temperature, currency and 100+ more units.

OneCalcApp AI

Ask OneCalcApp AI

What can I help you calculate?

Explore Calculators

Unit Converters

File Converters

Calendars & Festivals

Engineering Calculators

Construction Calculators

Electrical Calculators

Solar Calculators

Financial Calculators

Health Calculators

Scientific Calculators

Lifestyle & Daily

Vehicle & Automobile

Digital & Technology

Agriculture

Environment & Energy

Developer & Programmer

Online Video Downloader

Creator Tools

SEO & Website Tools

Why OneCalcApp?

Fast Browser Processing

No Upload Required

Secure by Design

Mobile Friendly

Engineering Grade

Instant Results

Free Tools

Latest Articles

How to Convert PDF to JPG

Solar Panel Size Guide

Understanding Currency Exchange

Engineering Unit Conversion Guide

Cable Sizing Tutorial

Frequently asked questions

What is OneCalcApp?