fxSolver
Free online math solver and formula library for engineers and scientists
About fxSolver
fxSolver is a free web-based math and engineering solver with a large community-driven library of pre-built formulas across physics, chemistry, electronics, mechanics, and classic math. Users can pick a formula, plug in values, chain results between formulas, and plot outputs — no installation or registration required for most features.
Pros & Cons
Pros
- Completely free with no paywall on core features
- Huge cross-discipline formula library saves time looking up equations
- Works in the browser on any device with no install or account required
- Formula linking makes multi-step engineering workflows much faster
- Useful for students, teachers, and working engineers alike
Cons
- Interface feels dated compared to modern math tools
- No mobile app — web-only experience
- Limited built-in symbolic math compared to dedicated CAS tools like Wolfram Alpha
- Community-driven library quality varies between formulas
Key Features
Formula Library
Thousands of pre-built formulas spanning physics, chemistry, electronics, computer science, mechanics, and classic math
Equation Solver
Algebraic solver that lets you plug in known values and rearrange to solve for any variable in a formula
Custom Formulas
Create your own formulas when one doesn't exist in the library and reuse them like any built-in entry
Formula Linking
Chain the result of one formula directly into another to build multi-step engineering calculations
Graphing & Plotting
Plot results visually by providing a list of input values or using the spreadsheet-like table input
Worksheets
Save your inputs and formulas as a worksheet that can be restored or shared with other users
No Installation
Runs entirely in the browser on any device without signing up for the core solver functionality
Pricing
- Full access to the formula library
- Equation solving for any variable
- Custom formula creation
- Graphing and plotting
- Worksheet saving (account required only to share)
Best For
Engineering Calculations
Quickly solve recurring engineering formulas without rebuilding them in a spreadsheet or programming language
Student Homework & Study
Look up and solve physics, chemistry, and math formulas while learning how each variable affects the result
Quick Back-of-Envelope Math
Plug numbers into any formula on the fly to check feasibility or sanity-check calculations during design work
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