How to Convert Area, Volume, and Density Units

Length factors live in how to convert length. This page is what happens after you square or cube them, and what happens when mass joins volume.

Area: square the length factor

If 1 ft = 0.3048 m, then

1 ft² = 0.3048² = 0.09290304 m².

1 m² = 10.7639104167 ft².

Land units:

• 1 hectare (ha) = 10⁴ m² exactly
• 1 acre = 4046.8564224 m² (international acre)
• 1 acre ≈ 0.40468564224 ha

A “quarter acre” is about 1012 m², not 1000 m². A football pitch is on the order of 0.7 ha; do not convert it as if it were 0.7 acres.

Area converter is m², cm², ft², in², acres, hectares. It will not accept a length and invent a square. The page runs in the browser; no account.

Volume: litres, cubes, and two gallons

1 L = 0.001 m³ = 1000 cm³ = 1000 mL (exact in SI).

1 m³ = 1000 L.

US customary liquid volume is a different historical pile:

• 1 US gal = 3.785411784 L exactly (231 in³)
• 1 US fl oz = 1/128 US gal ≈ 29.5735 mL
• 1 Imperial gal = 4.54609 L exactly
• 1 Imperial fl oz = 1/160 Imperial gal = 28.4130625 mL

A “gallon of milk” in the US is not a gallon of milk in the UK. A 500 mL bottle is 0.500 L, not “about a pint” unless you specify which pint (US liquid pint = 473.176 mL; Imperial pint = 568.261 mL).

Cubic feet show up in HVAC: 1 ft³ = 28.316846592 L. CFM is volume rate, not volume; converting 200 cfm as if it were 200 ft³ is a missing-time error, same class of bug as watts versus joules.

Volume converter is the page for L, m³, gal (pick US vs Imperial), in³, ft³.

Density: mass over volume

ρ = m / V. SI unit kg/m³.

Convenient twin: 1 g/cm³ = 1000 kg/m³.

Water at 3.98 °C is about 999.97 kg/m³; people use 1000 kg/m³ or 1 g/cm³ as the reference. Specific gravity (relative density) is ρ / ρ_water, dimensionless. 0.79 for ethanol is about 790 kg/m³, not 0.79 kg/m³.

Density converter changes kg/m³ ↔ g/cm³ ↔ lb/ft³ and similar. It does not compute density from a mass and a flask reading; that is how to calculate density from mass and volume. On Earth, a scale “kg” is usually good enough as mass for this. Newtons are not.

lb/ft³ is common in US materials sheets. 62.4 lb/ft³ is the usual water figure (about 999 kg/m³), which already tells you they rounded. Convert 62.4 lb/ft³ only if that is the number you were given; do not “improve” it to 1000 kg/m³ and still call it 62.4.

One numeric check: 2.5 acres and a 500 mL flask

2.5 acres × 4046.8564224 = 10117.141056 m² ≈ 1.0117 ha.

In ft²: 2.5 × 43560 = 108900 ft² (1 acre = 43560 ft² by definition of the international acre).

A 500 mL volumetric flask is 0.500 L = 5.00 × 10⁻⁴ m³.

Fill it with a liquid of density 1.15 g/cm³ = 1150 kg/m³. Mass = 1150 × 5.00 × 10⁻⁴ = 0.575 kg = 575 g.

That last line is a calculation plus two conversions (mL → m³, g/cm³ → kg/m³). The area piece did not participate. Mixing 2.5 acres into the flask math is how template articles used to read; it is not how a lab book works.

Confirm 2.5 acre → m² on the area converter. Confirm 500 mL → m³ on the volume converter (0.0005). Confirm 1.15 g/cm³ → kg/m³ on the density converter (1150).

Keep the family on the clipboard

Copy 10117 m², 0.500 L, 1150 kg/m³. Bare numbers get summed. If the next homework line is a length (fence around the 2.5 acres), go back to length; perimeter is not an area conversion.

Fuel gallons belong with fuel converter when the quantity is mpg or L/100km, not when you are converting a jerrycan. The hub is unit converters.