Referring to the previous article, **Calculate Specific Gravity (SG) in oilfield unit **, you get specific gravity (SG) from mud weight (ppg and lb/ft^{3}) and pressure gradient (psi/ft) but you may need to reverse calculation from specific gravity (SG) to mud weight or pressure gradient (psi/ft). In this article, you will learn how to convert specific gravity to mud weight and pressure gradient in both oilfield and metric unit by using simple formulas as follows:

# Convert Specific Gravity to Mud Weight In Oilfield Unit

## Convert specific gravity to mud weight in pounds per gallon (ppg)

Mud weight in ppg = specific gravity (SG) × 8.33

**Example:** specific gravity = 1.50

mud wt, ppg = 1.50 × 8.33

mud wt = 12.5 ppg

## Convert specific gravity to mud weight in lb/ft^{3}

Mud weight in lb/ft3 = specific gravity × 62.4

**Example:** specific gravity = 1.50

Mud weight in lb/ft^{3} = 1.50 × 62.4 lb/ft^{3}

Mud weight in lb/ft^{3} = 93.6 lb/ft^{3}

## Convert specific gravity to pressure gradient in psi/ft

Pressure gradient in psi/ft = specific gravity (SG) × 0.433

**Example:** specific gravity = 1.5

Pressure gradient in psi/ft = 1.5 × 0.433

Pressure gradient in psi/ft = 0.650 psi/ft

# Convert Specific Gravity to Mud Weight In Metric Unit

## Convert specific gravity to mud weight in kg/m^{3}

Mud weight in kg/m^{3}= specific gravity × 1000

**Example:** specific gravity = 1.5

Mud weight in kg/m^{3} = 1.5 × 1,000

Mud weight in kg/m^{3} = 1,500

## Convert specific gravity to mud weight in g/cc

Mud weight in g/cc = specific gravity × 1.0

**Example:** specific gravity = 1.5

Mud weight in g/cc = 1.5 × 1.0

Mud weight in g/cc = 1.5

## Convert specific gravity to pressure gradient in kPa/m

Pressure gradient in kPa/m = specific gravity (SG) × 9.81

**Example:** specific gravity = 1.5

Pressure gradient in kPa/m = 1.5 × 9.81

Pressure gradient in kPa/m = 14.7

Please also find the Excel sheet for this topic.

**Ref books: **

Lapeyrouse, N.J., 2002. Formulas and calculations for drilling, production and workover, Boston: Gulf Professional publishing.

Bourgoyne, A.J.T., Chenevert , M.E. & Millheim, K.K., 1986. SPE Textbook Series, Volume 2: Applied Drilling Engineering, Society of Petroleum Engineers.

Mitchell, R.F., Miska, S. & Aadny, B.S., 2011. Fundamentals of drilling engineering, Richardson, TX: Society of Petroleum Engineers.