BHA Collar Count Calculator

How many drill collars to supply your weight on bit — buoyancy-corrected

Required weight on bit (lb)

Collar air weight (lb/ft)

Collar length (ft)

Mud weight (ppg)

— collars

Minimum collars for your WOB (with 15% safety design factor)

Buoyancy factor = 1 − (mud weight ÷ 65.4). Standard practice keeps the neutral point in the HWDP, not the collars — apply margin. Estimate only.