Geometry and measurement

Rectangle dimensions calculator

Use the same length unit for both dimensions. Area is in squared units.

Your numbers

Use the units shown. Results update as you change valid inputs.

YOUR RESULT

Use the same length unit for both dimensions. Area is in squared units.

THE NUMBERS, EXPLAINED

How to use this calculator.

Use the same length unit for both dimensions. Area is in squared units.

Start with your inputs

Enter length, width. Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.

InputExample value
Length5
Width4

A worked example

With the example inputs above, area is 20. Change the inputs to explore your own scenario.

Putting the example numbers into the formula

Area
(5) × (4) = 20

Perimeter
2 × ((5)+(4)) = 18

Diagonal
hypot((5),(4)) = 6.403124

All results for the example inputs above
ResultExample answer
Area20
Perimeter18
Diagonal6.403124

How this is calculated

Area

a × b

Perimeter

2 × (a+b)

Diagonal

hypot(a,b)

Symbols and units
a
Length
b
Width

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Calculation steps and notation

hypot(x, y, …) is sqrt(x²+y²+…), the Euclidean length.

Assumptions and limits

Use the same length unit for both dimensions. Area is in squared units.

Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.

Questions about this tool

What does the result tell me?

Area; Perimeter; Diagonal. The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.

Why might another calculator differ?

Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: Use the same length unit for both dimensions. Area is in squared units.

Are my inputs stored or sent to AI?

Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.

Further reading

OpenStax: Prealgebra ↗

Background reading; this does not imply endorsement or independent review of SumFizz.

Review status

Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.

Read the quality report →