Bezplatné kalkulačky s viditelnými vzorci

Kalkulačka půjčky

Enter principal, annual interest rate and term to see the fixed monthly payment. The same annuity formula is used in every language version of this page.

Kalkulačka čisté mzdy

Enter gross pay and an effective tax rate. The engine multiplies; it does not apply UK bands, National Insurance, or another country’s withholding code. Use the dedicated UK or US tools when you need those rules.

Kalkulačka DPH (UK)

Enter a net or gross amount and a UK VAT rate to see the other side and the VAT amount. Rates follow UK VAT categories, not another country’s VAT/GST schedule.

Kalkulačka složeného úroku

Enter starting principal, annual rate, years and compounding frequency to see the future value and interest earned.

Kalkulačka ROI

Enter cost and gain (or final value) to see return on investment as a percentage. Optional holding period supports a simple annualised figure.

Kalkulačka marže

Enter cost and selling price (or revenue) to see gross margin and markup. The two percentages are not interchangeable.

Procentní kalkulačka

Three common percentage jobs on one page: part of a whole, reverse percentage, and change between two numbers.

Převodník měn

Pick two currencies and an amount. The rate comes from the public mid-market source used by the tool, not from a card issuer or bureau.

Kalkulačka BMI

Enter height and weight to see adult BMI and the usual category band. BMI does not measure fat, fitness or health on its own.

Formátovač JSON

Paste JSON to pretty-print or minify it. The parser runs in your browser so the document does not need to leave the device for this task.

Generátor hesel

Choose length and character classes. The generator draws from the browser’s cryptographic random source when available.

Spojit PDF

Add two or more PDFs and download a single file. Prefer on-device merge for confidential documents; read the on-page note for this build.