RBL Borrowing Base Calculator. Lender-ready output in one click.

Borrowing-base guide

How the public RBL calculator works

What is the borrowing base

A reserve-based lending borrowing base is the collateral value that a lender is willing to lend against an oil and gas reserve package at a point in time. It is not the same thing as proved reserve PV10, SEC standardized measure, market value, or a buyer's bid. It is a bank policy number. The bank starts with reserve volumes, forecast production, operating expenses, taxes, capital obligations, abandonment obligations, price assumptions, and reserve categories. It then applies a credit policy to decide how much of the reserve value is eligible collateral. The resulting borrowing base is compared with the current loan balance. If the base is greater than the loan balance, the borrower has availability or surplus. If the base is below the loan balance, the borrower has a borrowing-base deficiency and normally must cure that deficiency under the credit agreement.

The calculation matters because it is the recurring control point in an upstream credit facility. A producer may have a large reserve report and still have limited availability if the bank applies conservative prices, lower advance rates, non-producing caps, ARO deductions, concentration limits, or hedge adjustments. The public calculator on this page is intentionally narrow. It is built to show the mechanics of the borrowing-base bridge: reserve category PV, advance rate, non-producing cap, deductions, hedge uplift, lender haircut, and surplus or deficiency. It is not a substitute for a full engineering reserve report, legal credit agreement review, or bank redetermination model.

PDP vs PDNP vs PUD: lender categories

PDP means proved developed producing. These reserves are behind existing wells and currently producing through installed facilities. PDP barrels normally receive the highest advance because they have the most observable production history, the least remaining mechanical uncertainty, and the least capital still required before cash flow arrives. PDNP means proved developed non-producing. These reserves are developed but not currently producing. They may be shut in, behind pipe, awaiting workover, or otherwise not contributing current cash flow. PDNP receives a lower advance because timing, mechanical condition, and reactivation cost are less certain than PDP. PUD means proved undeveloped. These reserves require future drilling and completion capital before production begins. PUD carries the lowest advance rate because the bank must consider execution risk, capital availability, service cost inflation, regulatory timing, and development schedule.

This distinction is why a reserve report with the same headline PV10 can support very different borrowing bases. A portfolio dominated by PDP cash flow may receive materially more credit than a portfolio dominated by undeveloped inventory, even if both show similar total reserve value. Lenders are not simply buying the reserve report. They are underwriting repayment from cash flow under stress. The category split is therefore central to the borrowing-base outcome.

Advance rate conventions

Public lender guidance and market practice commonly describe advance rates in ranges rather than fixed universal rules. The default policy in this calculator uses 65% for PDP, 50% for PDNP, and 30% for PUD. Those defaults sit inside the conventional ranges referenced in public oil and gas lending materials: roughly 50% to 65% for PDP, 35% to 50% for PDNP, and 25% to 35% for PUD. A lender may use lower rates for a marginal borrower, weaker collateral, poor data quality, high operating cost, concentrated production, or a volatile price environment. A lender may use upper-range rates for clean PDP production, consistent reporting, adequate hedging, lower leverage, and strong sponsor support.

The advance rate is applied after the reserve category cash flow is discounted. For example, if PDP cash flow has $40 million of discounted value and the PDP advance rate is 65%, the preliminary eligible value is $26 million. PDNP and PUD are handled the same way at their own rates, then constrained by the non-producing cap. That separation is important. A higher PUD reserve value does not automatically translate into higher borrowing-base availability when the lender caps non-producing collateral.

Concentration caps and ARO deductions

Borrowing-base policies often include limits that are not obvious from a reserve report. One common limit is a cap on non-producing collateral. In this calculator, PDNP plus PUD eligible value cannot exceed a configured percentage of PDP eligible value. The default is 30%. If PDNP plus PUD would otherwise contribute $12 million but the PDP eligible value is $25 million and the cap is 30%, the non-producing contribution is limited to $7.5 million. The excess reserve value still exists, but it is not counted for borrowing-base availability under that policy case.

Another adjustment is the deduction for asset retirement obligations. ARO is the expected plugging, abandonment, and site restoration burden associated with the well set. A lender may deduct ARO directly, require a reserve, or adjust its credit view through other covenant and collateral mechanics. The calculator includes a simple ARO per well input so users can see the directional effect. A five-well sample asset with $75,000 per well of ARO takes a $375,000 deduction before the final haircut. In a mature PDP-heavy package, ARO can be a meaningful part of the borrowing-base bridge because the lender is evaluating net collateral protection, not just gross future revenue.

How banks haircut for price-deck risk

Price deck selection is one of the largest drivers of borrowing-base results. Public companies may disclose PV10 or standardized measure using SEC definitions, while banks typically run lender decks that are designed for credit stress. The default deck used here is the Haynes Boone Fall 2025 Energy Bank Price Deck Survey stress case embedded in the backend price-deck primitive. It starts with $55.44 per barrel WTI for 2026 and $3.20 per MMBtu Henry Hub for 2026, with differentials applied at the wellhead. Users can edit policy haircuts independently from the deck. A bank price haircut is a blunt way to represent additional lender conservatism against strip, SEC pricing, or borrower-provided forecasts.

Haircuts are deliberately shown as an explicit policy input. That makes the bridge auditable. If the borrowing base falls because the bank applies a 5% price haircut, that impact can be isolated from advance-rate changes, reserve mix, or ARO. The sensitivity table extends the same idea. It shows WTI down 10%, WTI up 10%, Henry Hub down 10%, Henry Hub up 10%, advance rates down five percentage points, and advance rates up five percentage points. Those are not predictions. They are simple stress cases that help a lender, sponsor, or borrower see which assumption moves the credit outcome most.

Spring vs Fall redetermination cycle

RBL facilities commonly redetermine the borrowing base twice per year, often in a spring and fall cycle. The exact mechanics depend on the credit agreement. The borrower delivers reserve information, production data, lease operating cost data, hedge schedules, ownership updates, capital plans, and other requested collateral information. The administrative agent and lender group evaluate that information under the facility's policies and propose or approve a borrowing base. The cycle matters because commodity prices, production decline, development timing, acquisitions, divestitures, and hedge positions can all move materially between redeterminations.

A spring 2026 redetermination label in this tool is only a reporting label. It does not change the math. The useful point is procedural: the borrowing base is not static. If the asset declines without reserve replacement, if the bank deck moves lower, if operating cost rises, or if PUD development slips, availability can tighten. If PDP performance beats forecast, hedges are favorable, costs fall, or debt is repaid, availability can improve. A transparent calculator lets the user separate these moving parts before a formal bank process begins.

Worked example with sample numbers

The sample asset is a generic five-well unconventional package with PDP, PDNP, and PUD rows. It uses 520 MBbl and 1,650 MMcf of PDP reserves, 120 MBbl and 430 MMcf of PDNP reserves, and 260 MBbl and 850 MMcf of PUD reserves. The default policy applies a 65% PDP advance, 50% PDNP advance, 30% PUD advance, a 30% cap on non-producing collateral, $75,000 per well of ARO, and a 5% bank price haircut. The current loan balance is set at $30 million so the result immediately shows whether the sample asset has surplus availability or a deficiency.

The engine builds a monthly decline forecast for each reserve category, caps cumulative production to the stated net reserves, prices monthly oil and gas through the lender deck, subtracts taxes and LOE, discounts the monthly net cash flow at the lender discount rate, and applies the category advance rate. PDP eligible value is counted first. PDNP plus PUD eligible value is then limited by the configured non-producing cap. ARO is deducted, hedge uplift is added if supplied, and the bank price haircut is applied to the resulting borrowing base. The output is intentionally compact: borrowing base, PV10, current debt, surplus or deficiency, category breakdown, sensitivity, and public citations. That is the minimum screen a credit committee or borrower CFO needs before deciding whether to spend time on a deeper reserve red-flag review.

Public references used by this calculator include the OCC Comptroller's Handbook for Oil and Gas Exploration and Production Lending, Texas Bankers Association borrowing-base guidance, SEC Regulation S-X 4-10, Crowell & Moring guidance on reserve-based energy loans, and Haynes Boone Energy Bank Price Deck Survey materials.