Conversion Guides
Each guide covers a conversion with a worked example, reference table, and FAQ. Open the calculator →
Conversion guides
- Imperial to metricLength, area, volume — 1 inch = 25.4 mm, 1 sq ft = 0.0929 m²
- Feet & inches to mm1 ft = 304.8 mm, supports feet + fractional inches (e.g. 5′ 3 1/2″)
- Square feet to square meters1 sq ft = 0.0929 m²; rooms, lots, and floor plans
- Acres to hectares1 ha = 2.4711 acres; 1 acre = 4,046.86 m²
- Cups to mLUS 236.59 mL · Imperial 284.13 mL · Metric 250 mL
- Gas mark to CelsiusGas mark 4 = 180 °C = 350 °F; full UK scale (¼–9)
- Grams to ounces1 oz = 28.35 g (weight); 250 g = 8.82 oz — not fluid ounces
- Kilograms to pounds1 kg = 2.2046 lb; 1 lb = 0.45359237 kg exactly
- Pounds to kilograms1 lb = 0.45359237 kg exactly; 100 lb = 45.36 kg — Build-mode weight
- Tonnes to kilograms1 tonne (metric ton) = 1000 kg exactly — Build-mode weight
- Metric tons to pounds1 metric ton = 2204.62 lb; compare metric ton, US short ton (2000 lb), UK long ton (2240 lb)
- For architectsDrawing-set workflow — feet + fractional inches, sq ft to sq m, acres to ha
Frequently asked
How do architects convert between imperial and metric?
Architects typically convert using the base factors: 1 inch = 25.4 mm for length, 1 sq ft = 0.0929 sq m for area, and 1 cu ft = 0.0283 cu m for volume. In practice, most use a dedicated converter rather than manual math to avoid compounding rounding errors across a drawing set.
What is the conversion factor from feet to millimeters?
1 foot equals exactly 304.8 millimeters. This is derived from the base conversion of 1 inch = 25.4 mm, multiplied by 12 inches per foot. For architectural work, avoid rounding until your final measurement. See Feet & inches to mm.
How do I convert square feet to square meters for a room?
Multiply the area in square feet by 0.0929 to get square meters. For example, a 150 sq ft room is about 13.94 sq m. Arch Convert does this automatically in the Area tab. See Square feet to square meters.
How many acres are in a hectare?
One hectare equals about 2.4711 acres. Going the other way, one acre is about 0.4047 hectares. A hectare is exactly 10,000 m², while an acre is 43,560 sq ft (4,046.86 m²). See Acres to hectares.
How many millilitres are in a cup?
A US cup is 236.59 mL. An Imperial (UK) cup is 284.13 mL. The Australian / metric cup is 250 mL. The difference matters for baking, where ratios affect rise and texture. See Cups to mL.
What is gas mark 4 in Celsius?
Gas mark 4 is 180 °C (350 °F). The UK gas mark scale runs from ¼ (110 °C) to 9 (240 °C). Gas mark 4 is the most common baking temperature, used for cakes, roast chicken, and most recipes that say ‘moderate oven’. See Gas mark to Celsius.
How do I convert 350 °F to Celsius?
350 °F is 176.67 °C, usually rounded to 180 °C in recipes (which is also gas mark 4). The formula is (°F − 32) × 5/9 = °C. Arch Convert converts instantly and shows the nearest gas mark alongside.
How many grams are in an ounce?
One weight ounce (avoirdupois) is exactly 28.349523125 g, rounded to 28.35 g. This is the ounce used for dry ingredients, not the fluid ounce, which measures volume (29.57 mL). So 250 g is about 8.82 oz. See Grams to ounces.
How do I convert kg to lbs?
Multiply kilograms by 2.2046 to get pounds. 1 kg = 2.2046 lb, and 1 lb = 0.45359237 kg exactly (the international avoirdupois pound). So 5 kg is 11.02 lb. See Kilograms to pounds.
How many kg is a pound?
One pound is exactly 0.45359237 kilograms. To convert lb to kg multiply by 0.45359237; to convert kg to lb multiply by 2.2046. See Pounds to kilograms.
How many pounds in a metric ton?
One metric ton (tonne) = 2204.62 lb. Compare: US short ton = 2000 lb (907.18 kg), UK long ton = 2240 lb (1016.05 kg). See Metric tons to pounds.
What's the difference between a ton and a tonne?
Tonne (metric ton) = 1000 kg = 2204.62 lb. US short ton = 2000 lb = 907.18 kg. UK long ton = 2240 lb = 1016.05 kg. See Tonnes to kilograms and Metric tons to pounds.
Is Arch Convert free to use?
Yes, Arch Convert is completely free with no signup, no paywall, and no usage limits. It was built by FluxCo Technologies for architects and construction professionals who deal with imperial and metric conversions daily.