Nine calculators — from bit hydraulics to casing burst, MAASP and cement volumes. Free, instant, in the browser — nothing leaves your machine. Diameters in inches (rig convention), everything else metric. The formula behind every answer is printed under it, so you can check us — and for survey-grade calculations (BHA sag, anti-collision), the free sag check and the live service run the full models.
Add a row per nozzle size in the bit — quantity × size in 32nds of an inch. TFA is the summed flow area; with a flow rate and mud weight you also get jet velocity, the pressure drop across the bit and hydraulic horsepower per square inch of bit.
| qty | size /32" |
|---|
Triplex or duplex — liner size, stroke length, pump rate, volumetric efficiency.
Uphole velocity of mud in the annulus — the number that carries cuttings.
Static mud column pressure at TVD — and the equivalent circulating density once annular pressure loss is added.
What the string really weighs in mud — the same factor the sag model applies to every collar (how sag works →).
Litres per metre — for tripping volumes, kill sheets and displacement planning.
Minimum internal yield pressure of pipe body with the API 12.5% wall-tolerance factor. Design rating, not a substitute for the manufacturer's data sheet — collapse is regime-dependent and deliberately NOT approximated here.
What the weakest point (normally the shoe) allows at surface with the current mud in the hole — the number on every kill sheet.
Open-hole annulus with excess, shoe track, and the mud volume that bumps the plug.
