To calculate a reserve ratio, divide a bank’s total reserves by its net transaction account deposits and multiply by 100. Total reserves are the sum of vault cash (currency and coin on the bank’s premises) and the balance the bank holds at a Federal Reserve Bank. Net transaction account deposits are the bank’s checking and other demand accounts after allowable deductions. The result, expressed as a percentage, shows how much of the bank’s deposit base is sitting in immediately available cash.
The Formula
Written out:
Reserve Ratio = (Total Reserves ÷ Net Transaction Account Deposits) × 100
Two inputs, one division, one multiplication. The work is in identifying what belongs in each input.
A Worked Example
Suppose a bank holds $80,000 in vault cash and $120,000 on deposit at the Federal Reserve. Total reserves come to $200,000. If net transaction account deposits are $2,000,000, the calculation is:
$200,000 ÷ $2,000,000 = 0.10
0.10 × 100 = 10 percent
The bank is holding 10 percent of its transaction deposits as liquid reserves.
What Counts in Total Reserves
The numerator has just two components:1eCFR. 12 CFR Part 204 – Reserve Requirements of Depository Institutions (Regulation D)
- Physical vault cash held on the bank’s premises (U.S. currency and coin the institution owns as an asset).
- The bank’s balance at a Federal Reserve Bank.
Nothing else goes into total reserves for this calculation. Treasury securities, interbank loans, and other liquid assets are not reserves in the regulatory sense, even though a bank may treat them as liquidity for its own management purposes.
What Counts in Net Transaction Account Deposits
The denominator starts with the bank’s transaction accounts and works down to a net figure. Transaction accounts are primarily demand deposits owed to the public — checking accounts and similar liquid accounts from which the depositor can make transfers or payments.
To reach the net figure, you start with total transaction accounts and then apply deductions and exclusions:1eCFR. 12 CFR Part 204 – Reserve Requirements of Depository Institutions (Regulation D)
- Exclude deposits owed to other depository institutions and to the U.S. government.
- Subtract cash items in the process of collection.
- Subtract demand balances owed by other depository institutions.
Regulation D also excludes several categories of liabilities from the definition of “deposit” entirely, so they never enter the calculation. These include trust funds properly segregated from the bank’s general assets, accounts payable, conditional or contingent obligations, and obligations whose proceeds are not used for lending or investment (such as debt issued to buy equipment or premises). Deposits payable only at offices outside the United States are also excluded.1eCFR. 12 CFR Part 204 – Reserve Requirements of Depository Institutions (Regulation D)
Time deposits (both small and large) are reported separately from transaction accounts and do not sit in the denominator of the reserve ratio calculation.
What the Percentage Tells You
A reserve ratio is a snapshot of liquidity against deposit obligations. A higher percentage means more cash is available to meet withdrawals, but less of the deposit base is deployed into loans and investments. A lower percentage means the bank is lending more of what it holds, with a thinner cash cushion.
The ratio does not, on its own, tell you whether a bank is safe or well-run. It measures one specific thing: immediately available cash against transaction deposits.
Reserve Ratio vs. Capital Adequacy Ratio
These two ratios get confused, and the distinction matters if you are analyzing a bank. The reserve ratio compares liquid cash and Federal Reserve balances to transaction deposits, so it speaks to day-to-day withdrawal capacity. The capital adequacy ratio compares a bank’s capital (equity and certain reserves) to its risk-weighted assets, so it speaks to the bank’s ability to absorb unexpected losses on loans and investments.2Federal Deposit Insurance Corporation. An Evaluation of the Denominator of the Reserve Ratio FDIC Staff Study Capital adequacy uses sophisticated risk modeling; the reserve ratio is a simpler liquidity measure.
The Current Federal Requirement Is Zero
On March 26, 2020, the Federal Reserve Board reduced the required reserve ratio to zero percent for all depository institutions across all three tiers of net transaction accounts. The Federal Reserve estimated the change freed up roughly $200 billion in reserves that banks could redirect toward lending.3Federal Reserve Board. Reserve Requirements
The zero percent requirement does not make the calculation obsolete. It means the calculated ratio is no longer measured against a mandatory minimum. The Board retains statutory authority to raise the ratio again, up to 3 percent on the lower tranche of transaction accounts and up to 14 percent on the upper tier.4Office of the Law Revision Counsel. 12 USC 461 – Reserve Requirements
The Board also continues to index two thresholds each year that would determine which tier applies if the ratios move above zero. For 2026, the reserve requirement exemption amount is $39.2 million in net transaction accounts, and the low reserve tranche is $674.1 million.5Federal Register. Regulation D: Reserve Requirements of Depository Institutions
Why Calculated Ratios Are Still Well Above Zero
Banks collectively hold approximately $2.9 trillion at the Federal Reserve as of early 2026, even though no rule requires them to hold anything. Two reasons drive the voluntary balances: they facilitate interbank payments and daily settlement, and they earn interest.
The Federal Reserve pays interest on reserve balances (the IORB rate) as a monetary policy tool.6Federal Reserve Board. Interest on Reserve Balances As of February 2026, the IORB rate is 3.65 percent, effective since December 11, 2025.7Federal Reserve Economic Data. Interest Rate on Reserve Balances (IORB Rate) Banks have little reason to lend overnight at a rate below what the Federal Reserve pays them risk-free, so IORB puts a floor under short-term rates and gives banks a direct financial incentive to keep balances parked at the Fed.
When you calculate a real bank’s reserve ratio today, expect a number well above zero. That is a business choice, not a compliance floor.