Square Footage Calculator

Nine shape calculators on one page.Match your surface to a diagram, calculate each measured section independently, and use quantity only for identical copies.

Shapes: 9
Length units: 6
Area outputs: 5

Shape 1 of 9

Rectangle

Floors, rooms, walls, lots, and other full rectangles.

Calculated result

Rectangle total

Formula 2.0.0

Total square footage600.00 ft²Quantity 1 · one measured shape

Square yards66.67 yd²Add a price above when you also need an entered-rate cost.

Total area · in²: 86400.00 in²
Total area · yd²: 66.67 yd²
Total area · m²: 55.74 m²
Total area · acres: 0.01 acres

Show calculation steps and assumptions

Convert every labeled length independently to meters.dimension in meters = entered dimension × exact unit factor
Apply the selected shape's plane-area formula without display rounding.A = length × width
Multiply the single-shape area by the whole quantity.total area = one-shape area × quantity
Convert the total area and apply the optional entered unit price.cost = total area expressed in the selected price unit × entered price

The result covers ideal plane geometry only. Split irregular projects into measured sections and add or subtract them explicitly.
Quantity assumes identical copies. The optional price is a user-entered rate and does not add waste, labor, taxes, minimum charges, or supplier rounding.

Shape 2 of 9

Rectangle border

Frames, edging, walkways, and uniform borders around an open center.

Shape 3 of 9

Circle

Round floors, pads, lawns, tables, and other full circles.

Shape 4 of 9

Ring

Circular borders, paths, collars, and annular surface areas.

Shape 5 of 9

Triangle with edge lengths

Use all three measured edges when no perpendicular height is known.

Shape 6 of 9

Triangle with base and height

Use one base and the perpendicular height to the opposite vertex.

Shape 7 of 9

Trapezoid

Four-sided areas with one pair of parallel bases.

Shape 8 of 9

Circular sector

A slice of a circle defined by radius and central angle.

Shape 9 of 9

Parallelogram

Slanted four-sided areas measured with a base and perpendicular height.

Plan-area measurement

Turn a measured footprint into defensible square footage

Square footage is a two-dimensional quantity, so the useful starting point is a clear boundary sketch rather than a material coverage guess. Record each measured zone, keep units attached, and decide which openings or unusable spaces belong in scope before adding areas.

Step-by-step guide · Plan-area measurement

Resolve recesses, triangles, and repeated spaces separately

Rectangle rule: area = length × width
Exact relationship: 1 yd² = 9 ft²
Boundary: Area is not perimeter or volume

Partition the outline
Divide an L-shaped space into non-overlapping rectangles. Measure each small region, calculate it once, and retain the sketch so nobody double-counts the shared corner.
Subtract true exclusions
A shaft, planter, or permanent opening is removed only if the project scope excludes it. Write the subtraction as its own line item instead of shortening a convenient dimension.
Multiply identical rooms last
Confirm that repeated rooms really share the same measured dimensions. Quantity is a multiplier for verified duplicates, not a substitute for measuring unlike spaces.

Turn a measured footprint into defensible square footage: Square footage is a two-dimensional quantity, so the useful starting point is a clear boundary sketch rather than a material coverage guess. Record each measured zone, keep units attached, and decide which openings or unusable spaces belong in scope before adding areas.

Draw the counting boundary before measuring the room

A floor plan rarely behaves like one perfect rectangle. Sketch the room, patio, wall, or lot and mark the exact surface being counted. A 12 ft by 10 ft central rectangle contributes 120 ft², but an attached 3 ft by 2 ft alcove is another 6 ft² only when it is inside the project boundary. Treating the farthest overall length and width as one bounding box would silently include missing corners.

Measurements should describe the same face of the object. Floor dimensions do not automatically represent wall finish area, and outside foundation dimensions do not automatically equal usable interior floor area. The result is an estimate of the geometry entered; lease definitions, appraisal conventions, and building-code floor-area definitions can use different inclusions.

Resolve recesses, triangles, and repeated spaces separately

Partition the outline
Divide an L-shaped space into non-overlapping rectangles. Measure each small region, calculate it once, and retain the sketch so nobody double-counts the shared corner.
Subtract true exclusions
A shaft, planter, or permanent opening is removed only if the project scope excludes it. Write the subtraction as its own line item instead of shortening a convenient dimension.
Multiply identical rooms last
Confirm that repeated rooms really share the same measured dimensions. Quantity is a multiplier for verified duplicates, not a substitute for measuring unlike spaces.

Reproduce a simple area, a repeated-room quote, and an invalid shape

Simple rectangle: 2 ft by 3 ft
Use Rectangle with length 2 ft, width 3 ft, quantity 1, and no price. The result is 6.00 ft² because 2 × 3 = 6; the supporting conversions display 0.67 yd² and 0.56 m².
Three equal rooms with an entered rate
Enter a 12 ft by 10 ft rectangle, quantity 3, and USD 4.25 per ft². One room is 120 ft², the total is 360 ft², and the entered-rate cost is $1,530. The cost is only area × the rate you supplied; it does not add tax, waste, or installation extras.
Triangle boundary: impossible edge lengths
Use Triangle with edge lengths and enter 2 ft, 3 ft, and 6 ft. Calculation must stop because the two shorter edges do not reach the third edge, so those measurements cannot enclose a triangle. Recheck the sketch instead of accepting a zero area.

Keep source precision through the area conversion

Feet entered from a tape

Convert inches or fractions to decimal feet before multiplying, and do not imply more accuracy than the tape, laser, or plan supplied.

Metric drawings

Work in metres and square metres first when that is how the drawing is dimensioned. NIST lists 1 ft² as 0.09290304 m², but conversion does not repair a rough field measurement.

Quoted material coverage

Use area only as the handoff quantity. A coverage rate, layout allowance, or waste percentage belongs to the product and installation plan, not to the definition of a square foot.

Send the measured surface to the right takeoff

Once the boundary is settled, move a floor surface into the tile quantity planner so tile dimensions and joint layout are explicit. A wall or ceiling belongs in the paint coverage worksheet, where coats, openings, and the can label affect the order. Outdoor ground intended for turf can be carried into the sod ordering calculator instead of borrowing an indoor finish assumption.

These follow-on tools answer different procurement questions. Keep the original area schedule beside every derived material total so a changed boundary can be traced without reconstructing the whole estimate.

Important limitations

Results model ideal plane geometry. Split irregular surfaces into measured shapes and add or subtract them separately. Quantity assumes identical copies; entered price does not include waste, labor, tax, delivery, minimum order sizes, or supplier rounding.

Review the stated scope, calculation method, assumptions, supported inputs, and effective dates, and obtain qualified advice before using a high-stakes result.

This formula passed its registered engineering tests and is published under an explicit site-owner policy authorization. No independent expert, QA, editorial, legal, or third-party review is claimed. Verify consequential results with a qualified professional.

Plan-area measurement

Turn a measured footprint into defensible square footage

Step-by-step guide · Plan-area measurement

Resolve recesses, triangles, and repeated spaces separately

Rectangle rule: area = length × width
Exact relationship: 1 yd² = 9 ft²
Boundary: Area is not perimeter or volume

Partition the outline
Divide an L-shaped space into non-overlapping rectangles. Measure each small region, calculate it once, and retain the sketch so nobody double-counts the shared corner.
Subtract true exclusions
A shaft, planter, or permanent opening is removed only if the project scope excludes it. Write the subtraction as its own line item instead of shortening a convenient dimension.
Multiply identical rooms last
Confirm that repeated rooms really share the same measured dimensions. Quantity is a multiplier for verified duplicates, not a substitute for measuring unlike spaces.

Draw the counting boundary before measuring the room

Resolve recesses, triangles, and repeated spaces separately

Partition the outline
Divide an L-shaped space into non-overlapping rectangles. Measure each small region, calculate it once, and retain the sketch so nobody double-counts the shared corner.
Subtract true exclusions
A shaft, planter, or permanent opening is removed only if the project scope excludes it. Write the subtraction as its own line item instead of shortening a convenient dimension.
Multiply identical rooms last
Confirm that repeated rooms really share the same measured dimensions. Quantity is a multiplier for verified duplicates, not a substitute for measuring unlike spaces.

Reproduce a simple area, a repeated-room quote, and an invalid shape

Simple rectangle: 2 ft by 3 ft
Use Rectangle with length 2 ft, width 3 ft, quantity 1, and no price. The result is 6.00 ft² because 2 × 3 = 6; the supporting conversions display 0.67 yd² and 0.56 m².
Three equal rooms with an entered rate
Enter a 12 ft by 10 ft rectangle, quantity 3, and USD 4.25 per ft². One room is 120 ft², the total is 360 ft², and the entered-rate cost is $1,530. The cost is only area × the rate you supplied; it does not add tax, waste, or installation extras.
Triangle boundary: impossible edge lengths
Use Triangle with edge lengths and enter 2 ft, 3 ft, and 6 ft. Calculation must stop because the two shorter edges do not reach the third edge, so those measurements cannot enclose a triangle. Recheck the sketch instead of accepting a zero area.

Keep source precision through the area conversion

Feet entered from a tape

Convert inches or fractions to decimal feet before multiplying, and do not imply more accuracy than the tape, laser, or plan supplied.

Metric drawings

Work in metres and square metres first when that is how the drawing is dimensioned. NIST lists 1 ft² as 0.09290304 m², but conversion does not repair a rough field measurement.

Quoted material coverage

Use area only as the handoff quantity. A coverage rate, layout allowance, or waste percentage belongs to the product and installation plan, not to the definition of a square foot.

Partition the outline

Subtract true exclusions

Multiply identical rooms last

Draw the counting boundary before measuring the room

Resolve recesses, triangles, and repeated spaces separately

Reproduce a simple area, a repeated-room quote, and an invalid shape

Keep source precision through the area conversion

Feet entered from a tape

Metric drawings

Quoted material coverage

Send the measured surface to the right takeoff

Important limitations

Partition the outline

Subtract true exclusions

Multiply identical rooms last

Draw the counting boundary before measuring the room

Resolve recesses, triangles, and repeated spaces separately

Reproduce a simple area, a repeated-room quote, and an invalid shape

Keep source precision through the area conversion

Feet entered from a tape

Metric drawings

Quoted material coverage

Send the measured surface to the right takeoff