Here we present two tables of the conversion factors for customary and SI units related to paper products.

Customary units to SI units

QUANTITYOTHER UNITSMULTIPLY BYFOR SI UNIT
Grammage (mass on ream basis)Pounds per ream (lb/ream) per 3000 square feet (lb/3000 ft2)1.6275Grams per square meter (g/m2)
Grammage (mass in grams per square meter)Pounds per 1000 square feet (lb/1000 ft²)4.8824Grams per square meter (g/m2)
Thickness Millimetres (mm)
Mils (or points or thousandths of an inch)
1000
25.4 
Micrometers (µm)
Apparent densityKilograms per cubic centimetre (g/cm²)Pounds per cubic foot (lb/ft²)1000
16.01846 
Kilograms per square meter (kg/m2) 
Tensile strenghtKilograms-force per 15 millimetre width (kgf/15 mm)
Pounds-force per inch (lbf/in)
0.65378
0.175127
Kilonewtons per meter (kN/m)
Tensile index (replaced breaking length)Kilometres breaking length (Km) 9.80665 Newtonmeters per gram (N m/g)
Tensile energy absorption (TEA)Kilograms-force meters per square meter (Kgf m/m2)
Foot pinds-force per square foot (ft lbf/ft2)
9.80665
14.5939
Joules per square meter (J/m²) 
Tearing strenghtGrams-force (gf) 9.80665 Millinewtons (mN)
Tear index (replaced tear factor) Computed as 100 grams-force per gram per square meter (100 gf(g/m²))0.0980665Millinewtons sq. meters per gram (mN m²/g)
Bursting strengthKilograms-force per square centimetre (kgf/cm²) 
Pounds-force per square inch – psi (lbf/in²)
98.0665
6.89476
Kilopascals (kPa)
Burst index (replaced burst factor)computed as grams-force per square centimetre per gram per square meter ((gf/cm² /(g/m²))0.0980665Kilopascals sq. meters per gram (kPa m²/g)
Z-direction strength properties (unit as appropriate)Kilograms-force per square centimetre (kgf/cm²)
Pounds-force per square inch (lbf/in²)
Foot pounds-force per square inch (ft lbf/in²)
98.0665
6.89476
2101.5
Kilopascals (kPa)
Kilopascals (kPa)
Joules per square meter (J/m²)
Concora Medium Test (CMT)Kilograms-force (kgf)
Pounds-force (lbf)
9.80665
4.44822
Newtons (N)
Ring Crush Test (RCT)Kilograms-force per centimetre (kgf/cm)
Pounds-force (for a 6-inch length) (lbf/6 in)
0.9806650.02919Kilonewtons per meter (kN/m)
Edgewise compressive strength (ECT)Pounds-force per inch (lbf/in)0.175127Kilonewtons per meter (kN/m)
Flat crush resistance of corrugated board (FCT)Kilograms-force per square centimetre (kgf/cm²)98.0665Kilopascals (kPa)

Length

1 meter1.094 yards
1 centimetre0.394 inches
1 millimetre0.039 inches
 1 yard 0.914 meters
 1 foot0.305 meters 
 1 inch2.54 centimetres 

 Weight

1 metric tonne0.984 long tons1.102 short tons
1 kilogram2.306 pounds35.274 ounces
1 gram0.035 ounces
1 pound453.6 grams
1 ounce28.35 grams

Surface 

1 square meter1.196 square yards10.764 square feet1550 square inches
1 square centimetre0.155 square inches
1 square millimetre0.002 square inches
1 acre0.4046 hectare
1 square yard0.836 square meters
1 square foot929 square centimetres0.0929 square meters
1 square inch6.452 square centimetres