Regulatory capital calculation, explained.

Why a bank weighs its loans before it counts its capital

The life of one loan's risk weight, in five steps

1. The loan is madeAn appraisal sets the property's value; the application records occupancy and income; the core system gets a set of codes.
2. The loan lives on the booksIt may be modified, go past due, change hands in a merger or lose its appraisal field in a system conversion.
3. Each quarter, the loan is weightedSomeone sorts it into an exposure class, checks its conditions, applies a weight and adds it to RWA. This is where a missing appraisal or a stale code turns into a wrong number.
4. The ratios are reportedRWA goes on Call Report Schedule RC-R, Part II, within 30 days of quarter end, and the ratios go to the board.
5. A rule changes, and every loan is weighted againThe 2026 proposal asks for facts the current rule never needed, such as each home's value at origination.

Step 3 is the subject of this guide. The bank and loans in the examples are fictional.

Four surprises in how loans are risk-weighted

Risk weight, RWA, CET1 and conversion factor: the four capital terms behind every section

Fourteen terms are defined in the one-page summary.

How risk-weighted assets and the capital ratios are calculated, step by step

In shortMultiply each on-balance-sheet exposure by its risk weight; convert each off-balance-sheet commitment to an exposure first, then weight it; add everything up. Divide each tier of capital by that total. The minimums are 4.5% CET1, 6% tier 1 and 8% total capital, plus a 2.5% buffer of CET1 above each, and a bank needs higher ratios still to be "well capitalized".

The calculation has three moves. First, every asset on the balance sheet gets an exposure class and a weight. Second, every off-balance-sheet item, such as the unused part of a line of credit, is multiplied by a credit conversion factor to turn it into an exposure amount, and that amount is weighted the same way. Third, the results are added: that sum is RWA.

Capital is the numerator, split into three tiers: common equity tier 1 (common stock and retained earnings, less deductions such as goodwill), additional tier 1 (certain preferred stock) and tier 2 (certain subordinated debt and part of the loan loss allowance).2,7

Minimums from 12 CFR 217.10; the buffer from 217.11, where payouts are limited in steps once the buffer falls to 2.5% or less; "well capitalized" from the prompt corrective action rules, here the FDIC's 12 CFR 324.403.2,8,9

The capital rules in force in October 2026, and the proposals still pending

In shortThe US standardized approach, in force since 2015, sets every weight a community or regional bank uses today. Three 2026 events matter: the community bank leverage ratio fell to 8% on July 1; the largest banks' leverage buffer changed on April 1; and the March 2026 capital proposals, which would rewrite home loan, business loan and commitment weights, closed for comment on June 18 and were still pending on October 31.

The standardized risk weights for loans, and the conditions that move each one

In shortEvery loan answers the same questions in order: past due or on nonaccrual? secured by real estate? construction? one-to-four family? first lien, underwritten, current and unmodified? The answers lead to 50%, 100% or 150%. The conditions are tested at each report date, so a loan's weight can change without anyone touching the loan.

Weights from 12 CFR 217.32; the OCC's 3.32 and the FDIC's 324.32 carry the same text.1 A loan with a qualifying guarantee or cash collateral may take a lower weight on the covered part under the credit risk mitigation sections.

Three conditions that change at the report date

Home loan risk weights: today's flat 50% and the proposed loan-to-value tables

In shortToday a qualifying first-lien home loan weighs 50% whatever its equity. The March 2026 proposal would weigh it 25% to 75% by loan-to-value, or 35% to 110% if rent or sale of the property repays it. Value means the value at origination, from an appraisal or evaluation that meets the appraisal rules. If the bank cannot calculate the ratio, the loan weighs 100%.

What counts as loan-to-value under the proposal

Weights from the proposal's Tables 5 and 6 and today's §__.32(g).3,1 The worked amounts are our arithmetic on an illustrative loan.

Why the original appraisal now sets a home loan's weight

The current rule already asks a bank to "base all estimates of a property's value on an appraisal or evaluation" that satisfies the appraisal rules, but the weight does not depend on the number.1 The proposal makes the number decide the weight, and the agencies say why they could not measure it themselves: "Due to the limitations of current regulatory reports, the agencies utilize the 2023 special data collection to estimate the LTV distribution of residential mortgage exposures".3

The Call Report does not carry loan-to-value. Many core systems carry it badly: values lost when an acquired bank's loans were converted, current automated values written over the original, or a field never filled for loans booked before a system change.

An evaluation counts. Since the 2019 appraisal rule, residential transactions of $400,000 or less need an evaluation in place of a full appraisal, and the 2010 interagency guidelines set what an evaluation must contain.19,20 A broker price opinion or an automated valuation run years later does not show the value at origination.

When a construction loan is high-volatility commercial real estate, and when it escapes 150%

In shortAn acquisition, development or construction loan for income-producing property weighs 150% as HVCRE unless it is excluded or exempt. One-to-four family construction, townhouses and for-sale condominiums included, is excluded outright. A commercial project is exempt only if three things hold: loan-to-value within the supervisory limit, borrower capital of at least 15% of the appraised as-completed value, put in before the bank advances and locked in until the loan is reclassified.

The 150% weight was new in 2015, and in 2018 Congress narrowed it. The 2019 interagency rule, in force since April 1, 2020, matched the regulation to the statute.11 A credit facility is HVCRE if it primarily finances the acquisition, development or construction of real property, has the purpose of turning it into income-producing property, and depends on future income, sale or refinancing for repayment.16

The 15% contributed-capital test, worked on an illustrative 72-unit apartment project

A developer plans a 72-unit rental apartment building; the appraisal puts its as-completed value at $20,000,000, so 15% is $3,000,000. Before the first advance it has contributed land the appraisal values at $1,800,000 and $900,000 of cash: $2,700,000, or 13.5%. Its financing plan says it will add $500,000 from the sale of another project next spring. That later money does not count, because it arrives after the bank advances. The loan is HVCRE at 150%.

Had the $500,000 come in before the first draw, and the loan agreement required it to stay, the project would have reached 16.0% and, with the loan-to-value inside the limit, been exempt: 100% today.

How unused lines of credit become risk-weighted assets, and why the 40% factor cuts both ways

In shortAn unused commitment is converted before it is weighted: 0% if the bank can cancel it unconditionally at any time, 20% if its original maturity is a year or less, 50% if longer. The proposal replaces 20% and 50% with one 40% factor. Long lines get cheaper; short ones double. Both answers depend on two terms of the loan agreement.

The current rule's conversion factors sit in §__.33. The unused portion of a commitment the bank can cancel unconditionally takes 0%. A commitment with an original maturity of one year or less that the bank cannot cancel takes 20%; one longer than a year takes 50%; guarantees, financial standby letters of credit, repurchase agreements and forward agreements take 100%.7

Original maturity decides it: the Call Report instructions measure it from the date the commitment is issued to its maturity, or to an earlier date on which the bank is scheduled to review the line, does so as a normal practice, and can cancel it unconditionally.4 A practitioner guide notes that "Preparers occasionally make the mistake of reporting them by remaining maturity instead".23

Today: 20% or 50% conversion × 100% weight. Proposal: 40% × 95%. The agencies' own figures: for commitments under one year "this change doubles the recorded exposure amount" and, with the 95% weight, "would increase the risk-weighted asset amount for unused commitments under one year by 90 percent"; their footnoted arithmetic for longer lines gives −24%.3

The March 2026 proposal by the numbers: 8.6% less RWA, most of it from home loans

In shortThe agencies estimate covered banks' RWA would fall 8.6% and their CET1 requirements by the same 8.6%. Residential mortgage RWA would fall almost 30%, commercial real estate 5%, other corporate about 7%. The relief is slightly smaller at small banks, 7.7% under $10 billion, partly because short commitments rise. Every estimate assumes banks can place their loans in the right band.

The agencies attach a condition that belongs next to every one of these numbers: "risk-weighted asset and capital impact estimates assume banking activity and risk exposures remain unchanged."3 An industry estimate also assumes the data. A bank that cannot prove a value at origination for a slice of its mortgage book gets 100% on that slice, double today's weight, so its own number can be worse than the industry's.

Two more changes travel with the weights: mortgage servicing assets would no longer be deducted above a threshold and would weigh 250% at every bank, including those using the community bank leverage ratio; and Category III and IV firms, the large banks just below Category I and II, would count most accumulated other comprehensive income (chiefly unrealized gains and losses on securities) in CET1, phased in over five years.3,25

Where the relief lands: what US banks hold

Does your bank calculate RWA at all? The 8% community bank leverage ratio decides

In shortA bank under $10 billion with a leverage ratio above 8%, modest off-balance-sheet exposures and little trading can elect the community bank leverage ratio and stop reporting risk-based ratios. The threshold fell from 9% to 8% on July 1, 2026. In mid-2025, 1,693 banks used it; the agencies expect about 2,039 at 8%. For an electing bank, the risk-weight proposal matters only for mortgage servicing assets.

An electing bank "shall be considered to have met the minimum capital requirements" and the well-capitalized ratios.24 The count of banks keeps falling: 4,238 FDIC-insured institutions filed for the second quarter of 2026, against 4,421 insured institutions at June 30, 2025.29,6 Final rule April 23, 2026, effective July 1, 2026.30,6

Reporting RWA on Schedule RC-R, Part II: columns, conversion and what the signature covers

In shortPart II spreads each balance-sheet line across weight columns from 0% to 1,250%, converts off-balance-sheet items first, and multiplies. Rows must foot to the balance sheet, so the schedule checks arithmetic. It never asks why a loan sits in a column. The report is due 30 days after quarter end, and its workpapers must be kept three years.

Every row of Part II is one balance-sheet line or off-balance-sheet category. Column A carries the amount from the balance sheet; column B the amounts deducted from capital or excluded from weighting on asset rows, and the credit equivalent amount after conversion on off-balance-sheet rows; the next columns are the weights. For items 1 through 8 and 11, the sum of the columns must equal column A.4

A qualifying first-lien home loan held for investment goes in item 5.a at 50%; a modified one, at 100%. HVCRE goes in items 4.b and 5.b at 150%. Unconditionally cancelable commitments go on item 19 at a 0% factor.4

Twelve risk-weighting errors that misstate a bank's capital ratio

In shortMost errors come from a fact assumed instead of read: a commitment called cancelable, a modification nobody told the capital team about, a construction loan tested against the wrong rule. Some flatter the ratio, some understate it, and a few only bite under the proposal. No public dataset counts them; your own re-test is the measure.

What software and AI can do in capital calculation, and what supervisors expect of it in 2026

In shortWeighting a classified loan is deterministic arithmetic, outside the 2026 model guidance's definition of a model. The hard part, reading appraisals, applications, memos and agreements for the facts, is where AI helps, and where its output has to be checked, cited and accepted by a person. The filing stays the bank's.

The April 17, 2026 model risk guidance, SR 26-2 (issued by the OCC as Bulletin 2026-13 and the FDIC as FIL-15-2026), replaced SR 11-7. It excludes "simple arithmetic calculations, such as those found within spreadsheets, as well as deterministic rule-based processes" from the definition of a model, and places generative AI models and their newer autonomous variants outside its scope.32

A risk-weight table is a deterministic rule. A generative AI tool that reads documents is outside the guidance's scope, which leaves the bank's own controls, the interagency third-party guidance ("the use of third parties does not diminish or remove banking organizations' responsibilities") and the Call Report attestation.33,31

Positions are illustrative; plot your own book by counting loans and multiplying balances by the weight difference in question.

Who calculates a bank's capital today, the hand-offs between them, and where the weeks go

In shortCapital planning owns the ratios, regulatory reporting owns the filing, credit owns the construction tests and loan operations owns the files. Quarterly RWA usually runs on core codes. A rule-change impact study is a spreadsheet project: pull the core, sample, extrapolate, and decide what to assume for loans with missing facts. Nobody publishes how long either takes.

An illustrative split for a regional bank; we found no published survey of time spent on capital impact studies or RC-R preparation. Time your next one.

Spreadsheets in house, outside preparers or capital software: how banks staff the work

Wendmoor Bank's 74,926 loans risk-weighted under both rules, from Monday's core close to Thursday's capital committee

In shortThis is the example from the top of the page, inside the product. When the core closes, six agents weight all 74,926 loans and 2,904 commitments under the current rule and the March 2026 proposal, reading 11,354 documents in 8,416 loan files for the facts the core lacks. Noor Haddad, VP of capital planning, works through what they found; the chief risk officer approves the result for Thursday's committee.

1

The whole book walks the tree at core close

On Monday, October 12, 2026, the September core closes at 6:12 am. The agents map every loan to an exposure class and send it down the same questions Part A described: past due, secured by real estate, construction, one-to-four family, first lien and performing, value at origination proved, repaid from rents.

In the whole-book view, each branch carries its loan count and each leaf its balance and RWA under both rules. 31,640 owner-occupied home loans land in Table 5; 218 land on "LTV cannot be calculated".

2

A 2017 appraisal the core never had

Noor picks RM-19-044817, the Juniper Hollow Road loan. Its value field has been blank since the 2019 conversion of Kettle Creek Savings. The appraisal reader found the Form 1004 in the imaged file: effective March 14, 2017, $412,000, by Carla Brandt, certified residential appraiser, page 2.

$251,380 ÷ $412,000 is a loan-to-value of 61.0%: Table 5, the 60–80% band, 35% under the proposal. Today it is 50%. The right rail shows each fact with its document and page.

3

The same loan with the core's data alone

Noor switches the values to "Core only". With no value at origination, Juniper Hollow falls to "LTV cannot be calculated": 100%, $251,380 of RWA instead of $87,983.

Across the book, 3,912 home loans ($853.6 million) have no value at origination in the core, 3,588 of them from Kettle Creek. The agents found a valid value for 3,694: 3,412 appraisals, 214 evaluations and 68 condominium appraisals.

4

The capital effect, added up from the loans

Total RWA falls from $30,994.2 million to $28,631.7 million under the proposal, 7.6%, and the CET1 ratio rises from 11.65% to 12.62% on $3,612.0 million of CET1 capital. Loan RWA alone falls 8.2%, close to the agencies' 8.6% industry estimate.

The bridge shows where it comes from, and the CET1 panel says what the loan files are worth: the $518.0 million of RWA the core alone would leave at 100%. The panel rounds that to 23 basis points (12.62% less 12.39%); unrounded it is about 22 (12.615% against 12.391%).

5

A committee summary that people sign

The capital impact writer drafts the committee item: what moves the ratio, what the files are worth, the corrections to today's reporting and the method. Nothing goes to the committee until Noor signs as capital planning lead and Martin Oyelaran, the chief risk officer, approves.

Corrections to Schedule RC-R are Tom Carrick's decision as regulatory reporting manager, before the Q3 Call Report is due on October 30.

Twelve more screens, from a rented duplex to the rule versions a run may use

In shortOne loan's path is the story; these screens show the rest. Each tree screen shows which branch a loan took and the fact that decided it. The lists show where the file disagrees with the core, what is still missing and what it would be worth if found. One sample loan is weighted under the wrong HVCRE rule, and its caption gives the correct treatment.

Select a screen to open it larger. The bank, people, properties, loans and figures are fictional. Dates and times are shown in US form.

Six agents read the files and weight the book; the capital planning lead and the CRO decide

In shortEach agent has one job and limits it does not cross. None of them changes a core record, the capital plan or a regulatory filing, and none of them invents a value. The capital planning lead accepts each finding and signs; the chief risk officer approves for the committee; the regulatory reporting manager decides any change to Schedule RC-R.

Six agents, from the exposure mapper to the capital impact writer

Who accepts findings, who approves the impact, and who owns the RC-R filing

An override keeps the core's answer only with a written reason and a second person's approval. Every run, finding, override and signature is on the audit trail with who did it and when.

The capital planning, risk and reporting team in the screens

From core extracts and imaged appraisals to a page-cited risk weight for every loan and a signed CET1 bridge

In shortIt reads what the bank already keeps: core extracts at each close, imaged loan files, credit memos and agreements, the rule texts, CET1 capital from the general ledger and non-loan RWA from the reporting system. It leaves behind a weight per loan under each rule with its fact and page, a CET1 bridge, findings, a missing-data list and a signed summary. The core, the plan and the filing stay where they are.

Core banking, document imaging, regulatory reporting and the general ledger: where each fits

Three principles behind every risk weight the agents assign

The solution's design target is every weight traced to a fact, its page and the rule paragraph, and a whole-book re-run in hours when a rule version changes. Both are targets, to be measured on your own book.

What an unproved risk weight costs you: capital held for nothing, filings to amend, weeks of spreadsheet work

In shortThree costs. A weight you cannot prove keeps the conservative number, so capital sits idle against risk you could have shown was lower. A weight that is wrong today misstates the Call Report and can mean an amended filing. And every rule change restarts a manual study. The published figures frame the stakes; your own book sets the size.

Measuring your own risk-weighting gaps in a week

What unproved weights cost that no capital calculator shows

What proving each loan's weight from the file could be worth to your capital ratio

In shortThe main return is capital, measured in basis points of CET1 for the facts you can prove. The calculator asks for your RWA under the proposal with core data only, your CET1 capital, the home loan balances with no value at origination, how many of their files hold one, and the weight they would get. Every input marked illustrative is an assumption to replace.

Six ways proving weights from the file pays back

Calculate the CET1 basis points your loan files are worth

The gain grows with the balances you can prove and shrinks as your RWA grows. A community bank with a large acquired mortgage book can find more basis points than a bigger bank with clean data.

Readiness to weight loans from their files: appraisal values, HVCRE worksheets, commitment terms and owners, scored

In shortPick the answer closest to your bank today. Eight questions score 0 to 2; the last is for reflection. The meter adds up your score, and each question says why it matters and what a strong answer sounds like.

Explore, pilot or implement: what your capital calculation score suggests

Vendor questions on rule versions, appraisal evidence, missing files and who changes the Call Report

In shortAsk every vendor the same questions, us included. The answers show whether the tool calculates from whatever it is fed or proves the facts, how it handles the gaps, who decides, and how you would test it on your own loans.

We found no published independent test of any capital calculation vendor's accuracy, as of October 2026. A test on loans your team has already proved by hand is the fairest comparison.

Prove 200 loans by hand, then weight a few thousand from their files: a capital pilot before the final rule

In shortMeasure the gaps first, then weight a sample from the files with known answers, then decide with three numbers. None of these steps commits you to a vendor, and all of them prepare your plan for the final rule.

1. Count the gaps: home loans with no value at origination, construction loans by flag and property type, commitments by product code.
2. Prove 200 loans by hand, a mix of acquired home loans, construction loans and commitments, so the test has known answers.
3. Choose a pilot portfolio of a few thousand loans with imaged files, and approve the rule versions and evidence standards.
4. Run in parallel with your quarter-end process, your team accepting or rejecting every finding.
5. Decide with three numbers: values and facts found correctly, findings confirmed, and analyst hours.

Five numbers that decide a risk-weighting pilot

Risk-weighted assets, HVCRE, the 2026 proposal and the CBLR: what capital teams search for

In shortThe questions capital, reporting and risk teams search for most, each answered on its own.