# Calculators

This section contains tools for common calculations in mass spectrometry.

**Web page-based calculators:**

- FTICR calculations - for Fourier transform ion cyclotron resonance (FTICR) mass spectrometry, calculate resolving power and frequency for a given peak, based upon instrument parameters, and the acquisition time.
- Mass, m/z, and mass errors - from observed and theoretical m/z values, calculate the mass error in parts per million (ppm), calculate the theoretical m/z from a molecular formula, or calculate the m/z range for an m/z of interest plus/minus a mass error in ppm.
- DBE and Z - calculate the double bond equivalents (DBE) or hydrogen deficiency (Z) from a molecular formula.

**Online Shiny apps:**

- Calibration HelpeR - create reference lists for calibrating mass spectra
- Method Digester - view Method files for mass spectrometers manufactured by Bruker Daltonics
- Kendrick Mass Defect Tool - create Kendrick mass defect plots from data
- VKSim - create van Krevelen diagrams and simulate different reaction pathways for complex mixtures