Newton's second law of motion — force equals mass times acceleration — is one of the fundamental equations in physics, and this calculator lets you solve for any one of the three variables when you know the other two.
Select which variable you want to solve for, enter the two known values, and the result updates instantly using the rearranged form of the equation appropriate for whichever variable you're solving.
This is useful for physics coursework, quick engineering estimates, or checking a calculation by hand, with standard SI units (newtons for force, kilograms for mass, meters per second squared for acceleration).
Because everything runs locally in your browser, results appear instantly and nothing you type or upload is ever sent to a server.
Bookmark this page if you expect to use this tool regularly — it loads fast and behaves the same way every time, with no account needed.
This kind of task shows up constantly in everyday writing, coding, design, and admin work, which is exactly why a dedicated, focused tool saves so much back-and-forth.
A tool that does one job well, without a cluttered interface or unrelated features competing for attention, tends to be faster to use than a heavier all-in-one app.
If you find yourself needing this often, keeping this page open in a tab is usually faster than digging through a bigger software suite's menus.
Frequently asked questions
What units does this use?
Standard SI units: newtons (N) for force, kilograms (kg) for mass, and meters per second squared (m/s²) for acceleration.
How is this rearranged to solve for mass or acceleration?
Since F = ma, solving for mass gives m = F/a, and solving for acceleration gives a = F/m — the calculator applies whichever rearrangement matches your selected variable.