17 drilling and well control calculators. Every answer comes with the formula and the numbers you put in it. Works with no signal.
No thousand-formula index to scroll. The tools a drilling crew actually reaches for, each with real input fields — not a picture of an equation.
Tap once and the result opens up into the formula with your own numbers substituted in. You can check the arithmetic instead of trusting a black box — which is also why it works as a practice tool for well control school.
High-contrast black on safety yellow so the screen is readable outside in direct sun, with buttons big enough to hit wearing gloves and a custom number pad instead of the fiddly system keyboard.
Everything runs on the device. No login, no loading spinner, no "check your connection" when you're on location. Save a calculation and it stays in your history; with Pro it syncs across your iPhone and iPad through iCloud.
Set depth, diameter, pressure, volume and mud weight independently, so a mixed-unit rig works properly. Change a unit later and your stored values convert instead of vanishing — and every result prints the unit next to the number.
The maximum influx you could take and still circulate out without breaking down the shoe. TallyRig gives you MAASP, annular capacity and maximum influx height and volume, in either EMW or gradient mode.
Kill mud weight, initial and final circulating pressure, and formation pressure from your
shut-in readings. KMW = OMW + SIDPP ÷ (0.052 × TVD)
Bottomhole pressure from mud weight and true vertical depth, and the reverse — turning any
pressure back into an equivalent mud weight. 0.052 × MW × TVD
Where the string is stuck, from measured stretch and overpull, plus safe pull limits by pipe grade. The calculation you want fast, and correct, at the worst possible moment.
Barite sacks to raise mud weight and the resulting volume increase, plus slug weight and
dry-pipe length. 1470 × (W₂ − W₁) ÷ (35 − W₂) per 100 bbl
Pipe and annular capacity, slurry volume and sacks of cement, pump output for triplex or
duplex, annular velocity and bottoms-up strokes. (Dh² − Dp²) ÷ 1029.4
Everything below, forever, with no account and no ads.
A single in-app purchase. Not a subscription, and it doesn't expire.
Yes. Every calculator runs on the device. There's no login and no network call needed to get an answer, so it works on location with no bars. If you're a Pro user, iCloud sync happens in the background when a connection comes back — it never blocks a calculation.
Kill Sheet, Kick Tolerance, Hydrostatic, EMW from Pressure, Mud Weight-Up, Buoyancy, Pipe Tally and the Unit Converter. The show-the-formula view works on all of them. A one-time purchase unlocks the other nine plus save, share, PDF and history.
No. Pro is a single in-app purchase that doesn't expire. Restore Purchases brings it back on a new device.
Yes, and it does mixed units — which is the point. Depth in ft or m, diameter in in or mm, pressure in psi, bar, kPa or MPa, volume in bbl, m³ or gal, mud weight in ppg, SG or kg/m³. Set each one independently to match your rig. Change a unit later and your stored values are converted, not cleared.
Plenty of people do, because the show-the-formula view walks through the substitution step by step rather than just handing you a number. It's a practice and cross-check tool — it is not a course, and accredited Driller and Supervisor level training requires simulator time that no app can replace.
English, Português (Brasil) and Español. It follows your phone's language by default, and you can override it in Settings. Rig acronyms — MW, TVD, SIDPP, MAASP, BOP — stay in English everywhere, because that's how they're used on a rig floor.
There's no account, no ads and no analytics tracking you around. Calculations stay on your device (and in your own iCloud, if you're Pro). Purchases are handled by Apple and RevenueCat. The full detail is on the privacy page.
Free to download. Eight calculators free forever. Every result shows the formula.
