Added two more Geology calculators: Gross Rock Volume and Net Rock Volume, the starting steps of a reservoir volumetric estimate — enter an area and gross thickness (plus a net-to-gross ratio for the net version) to get a rock volume in acre-feet or cubic meters.

Added two more Geology calculators: Target Window Thickness, which checks how much vertical room a landing target offers between its top and base picks, and Formation Top Projection, a "dead reckoning" tool that projects a formation top's expected depth ahead of the bit from a known reference depth, distance, and dip.

Added two Geology calculators: Structural Closure (Trap Height), which finds the maximum column height a trap's geometry can support from its crest and spill point depths, and Structure Gradient, a quick regional-dip-rate tool between two structural picks — the first of several planned additions to Geology's Structure & Mapping section.

Added a Primary Term Expiration calculator to Land & Ownership — enter a lease's effective date and primary term to find the date its primary term expires, with a built-in date picker and a clear reminder that production can extend a lease beyond this date.

Your imperial/metric unit setting is now remembered across visits, the same way your light/dark theme already is.

A failed calculation now always shows a clear error message, in every input mode — Standard, Range/P10-P90, Batch, and Depth Series — instead of only Standard mode. Loading a shared link or a "Load example" that fails to calculate now also shows an error instead of failing silently.

Added five more Geology calculators, completing the discipline's initial buildout at eleven: TVT/TST Correction for wellbore deviation, Fault Throw, Heave & Net Slip, Shale Gouge Ratio (a fault-seal risk indicator), Rock-Eval Source Rock Indices (Production, Hydrogen, and Oxygen Index), and a Sclater & Christie Decompaction tool for burial-history reconstruction.

Added a new Geology discipline with six calculators: Three-Point Problem (strike & dip from three points), Apparent Dip from True Dip, Isopach from Isochore Thickness, Formation Top Subsea Depth, ΔlogR Total Organic Carbon (a log-derived source-rock richness estimate), and a Lopatin Time-Temperature Index tool for thermal-maturity screening.

Added a new Depth Series input mode to Clay Volume (GR Linear), Neutron-Density Porosity, and Water Saturation (Archie) — load a LAS file and run the calculation across every depth in the log at once, with results shown as a table and available as a CSV download.

Fixed a bug in LAS file loading where, if one log curve had a gap (a "null" reading) at a different depth than another curve, values from mismatched depths could be silently paired together. This affected the Pay Table tool and the crossplot charts on the Crossplots page.

Search is now faster and more forgiving of typos — press Ctrl+K (or Cmd+K) from anywhere to search all calculators.

Every calculator can now export a report. A new "Export Report" button lets you pick which sections to include — inputs, results, chart (where available), description, variables, assumptions, limitations, region notes, and references — and download the result as a PDF or a PNG image. Reports render in a clean, print-friendly light layout regardless of your site theme, and every export includes the site disclaimer.

Added interactive charts to six calculators: Eaton Pore Pressure and Casing Collapse Pressure (Drilling), IPR — Vogel's Equation and the Hyperbolic Decline forecast (Reservoir), Water Saturation (Archie) (Petrophysics), and the Shuey AVO Approximation (Geophysics). Each chart updates live as you change inputs, matches your light/dark theme, and follows your imperial/metric unit setting.

Added four Land & Ownership calculators, completing the discipline's Spacing and Revenue sections: Spacing/Drilling Unit Acres and Horizontal Well Allocation Factor (Spacing), plus Revenue Payment Estimate and Division Order Decimal Verifier (Revenue).

Merged Annual Rental and Delay Rental into a single Lease Rental calculator, and corrected an outdated federal lease rental rate figure in the process — the two tools turned out to describe the same underlying payment (private "delay rental" and federal/state "annual rental" are the same mechanism under different names, not two different things).

Added two Lease Calculations tools to Land & Ownership: Lease Bonus and Lease Rental.

Added a new Land & Ownership discipline with seven calculators: Gross Acres to Net Acres, Net Mineral Acres, Working Interest Share, Net Revenue Interest, Royalty Interest, Overriding Royalty Interest (ORRI), and Back-in / Carried Interest. Net Revenue Interest has moved here from Economics — the link is unchanged if you'd bookmarked or shared it — and Economics now stays focused on project valuation (NPV, IRR, payback, LOE, economic limit rate).

Added a new Economics discipline with six calculators: Net Present Value, Internal Rate of Return, Payback Period (simple and discounted), Net Revenue Interest, Lease Operating Expense per Unit, and Economic Limit Rate. The Economic Limit Rate tool now links directly to the existing EUR from Decline Parameters calculator in Reservoir, so you can derive the economic cutoff rate it needs instead of guessing it.

Added two Fluid Properties calculators: a Wilson equilibrium-ratio (K-value) tool, and a compositional bubble-point-pressure tool built on top of it — a different method from the existing bubble point calculator, useful when you know a mixture's composition rather than its API gravity and gas-oil ratio.

Added six more Fluid Properties calculators: oil density, gas viscosity, gas compressibility, and a new set of water-property tools — water compressibility, water formation volume factor, and water viscosity.

Added a Fluid Properties discipline for PVT correlations. New calculators: gas Z-factor (Hall-Yarborough and Dranchuk-Abou-Kassem), oil viscosity (dead, saturated, and undersaturated), and undersaturated oil compressibility. The existing PVT tools — black-oil PVT, bubble point pressure, gas FVF, and gas-oil ratio — now live in this discipline (their links are unchanged). Inputs on these tools now show a gold advisory when a value falls outside the range the correlation was originally fitted to.

Added a "Load example" button to every calculator that pre-fills realistic, verified values and calculates them, so you can see how a tool works before entering your own data. A small badge shows whether each example comes straight from published literature or was independently verified against the calculator's own formula.

Added a "Report an issue" link on every calculator page, and this changelog.

Added privacy-friendly usage analytics (Plausible) — no cookies, no personal data collected, no cookie banner required.

Every calculator now has its own dedicated, search-indexed page and a shareable link that reproduces your exact inputs (previously the entire site was one URL).

Added a consulting-services link, a new About page, and a fully rewritten Disclaimer (11 sections, up from 7) covering software limitations and external references.

Fixed a display-precision bug affecting batch-mode results, sensitivity sliders, and input range-warning messages.

Fixed a display-precision bug affecting 79 of 100 calculators, where some results were rounded to the wrong number of decimal places or shown in scientific notation unnecessarily.

Added a pore compressibility correlation (Newman 1973, sandstone & limestone) to Petrophysics.

Geophysics: added Lambda-Rho/Mu-Rho and Gardner density-from-velocity tools; moved the Rw-vs-Temperature calculator into Petrophysics, next to the related salinity tools.

Geophysics: added seismic resolution and attribute tools — dominant wavelength, tuning thickness, Fresnel zone radius, instantaneous amplitude/phase/frequency.

Geophysics: added AVO and elastic impedance tools — exact Zoeppritz equations, Aki-Richards and Shuey approximations, Connolly elastic impedance, AVO classification.

Geophysics: added interval-velocity and depth-conversion tools — checkshot survey, Dix equation, average velocity, Slotnick V0-k.

Petrophysics: added rock-physics tools — capillary height above free water level, the Leverett J-function, pore compressibility (Hall 1953) — and a formation-water salinity/resistivity correlation.

Redesigned dashboard search and made sidebar categories collapsible for easier navigation as the calculator library has grown.

Assumptions, limitations, and region-specific notes are now shown on every calculator page (previously present in the data but not displayed).

Reservoir: added fluid-property (PVT) tools, a material balance tool, and a gas well deliverability tool.

Added site-wide search — any calculator can now be found by name, category, or tag from anywhere on the site.

Rebranded from PetroCalc to BauerCalc.

Added the Geomechanics discipline — overburden and effective stress, wellbore stability, and compaction pore pressure.

Fixed a bug where selecting a formation could overwrite unrelated inputs with incorrect values carried over from a different discipline's calculations.

Fixed calculator inputs not pre-filling with their default values.

Drilling: added well control tools — MAASP, kill mud weight, formation integrity/LOT, kill sheet circulating pressures, kick tolerance.

Drilling: added a buckling calculator showing both sinusoidal and helical onset limits side by side, since the helical constant is genuinely unsettled in the published literature.

Drilling: expanded from 4 to 18 calculators — hydraulics, torque & drag, and casing design tools.

Added the Reservoir Engineering discipline; added a dark theme toggle (light theme is the default).

BauerCalc (then PetroCalc) launched with an initial set of Petrophysics, Reservoir, and Drilling calculators.