Rearrange Formula Calculator

Work out rearrange formula instantly with clear inputs, formula shown and shareable results.

About Rearrange Formula Calculator

Rearranging a formula applies inverse operations to both sides until the wanted variable stands alone. The same balance rules used to solve equations apply to symbols as well as numbers.

Formula

Rearrangements of ax + b = c

x = (c − b)/a, a = (c − b)/x, b = c − ax, c = ax + b

Worked example

With the default values below, Rearrange Formula Calculator returns Value of the chosen subject of 5.00000000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Coefficient a in ax + b = c: 4
Constant b: 9
Result c: 29
Rearrange to findone of x, a, b, c: x

Results

Value of the chosen subject: 5.00000000
Rearranged formula: x = (c - b) / a
Subject solved for: x
Check of the original left-hand side: 29.00000000

Step by step

1Values used
2Rearrangements of ax + b = c
3Value of the chosen subject= 5.00000000
4Rearranged formula= x = (c - b) / a
5Subject solved for= x
6Check of the original left-hand side= 29.00000000

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 8 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Solve 4x + 9 = 29 for x.

Subtract 9 to get 4x = 20, then divide by 4 to get x = 5.

Why does dividing need care?

You must never divide by a quantity that could be zero, which is why the calculator refuses a = 0 when solving for x.