Money Supply Calculator — Money Multiplier & M2 Estimate
Model how fractional-reserve banking expands the monetary base: enter the M0 base and the reserve requirement ratio to see the money multiplier, the theoretical broad money supply (M2 estimate), and how much new deposit money is created through lending.
%
Monetary base × money multiplier — the theoretical maximum
- 1
Reserve ratio as decimal
10% ÷ 100 = 0.1 - 2
Money multiplier
1 ÷ 0.1 = 10 - 3
Broad money supply
1,000,000 × 10 = 10,000,000Monetary base × money multiplier gives the theoretical maximum broad money.
How does this calculator work?
Money multiplier = 1 ÷ reserve ratio. Broad money supply = monetary base × multiplier. A $1M base with a 10% reserve requirement can theoretically support $10M in deposits. In practice, excess reserves, public cash-holdings, and regulatory changes mean actual money supply differs from this theoretical maximum.
Formula
How this is calculated
In a fractional-reserve banking system, banks are required to keep only a fraction of each deposit in reserve and can lend the rest. Each loan becomes a new deposit elsewhere, which can be re-lent again, multiplying the initial base money into a much larger supply of broad money. The simple money multiplier — 1 divided by the reserve ratio — gives the theoretical maximum for this expansion.
For example, with a 10% reserve requirement and a $1,000,000 monetary base, the multiplier is 10× and the theoretical money supply is $10,000,000. The initial $1,000,000 in reserves supports $9,000,000 of new deposits created by repeated rounds of lending.
This model has important limitations: in practice, banks hold excess reserves (especially post-2008), the public holds some cash outside the banking system, and central banks manage money through open-market operations rather than simply setting a reserve ratio. Many advanced economies (including the US since 2020 and the UK) no longer impose a formal reserve requirement. Treat this as a theoretical illustration of the mechanics, not a precise prediction of a country's actual money supply.
Frequently asked questions
The money multiplier (1 ÷ reserve ratio) shows the maximum number of dollars of broad money that can be created from each dollar of base money. A 10% reserve ratio gives a multiplier of 10: a $1 base can theoretically support $10 in deposits.
Banks voluntarily hold excess reserves (cash cushion beyond the legal minimum), the public keeps some cash outside banks, and central banks adjust conditions through other tools. The simple multiplier is an upper bound, not a precise forecast.
No. The Federal Reserve reduced reserve requirements to zero in March 2020. However, the conceptual model remains useful for understanding how fractional-reserve banking amplifies money creation — central banks now manage conditions primarily through interest rates and open-market operations.
Also known as
TG we-Calculate Editorial Team. (2026). Money Supply Calculator — Money Multiplier & M2 Estimate [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/money-supply-calculator
TG we-Calculate Editorial Team. "Money Supply Calculator — Money Multiplier & M2 Estimate." TG we-Calculate. 2026. https://we-calculate.com/calculator/money-supply-calculator.
TG we-Calculate Editorial Team, "Money Supply Calculator — Money Multiplier & M2 Estimate," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/money-supply-calculator
@misc{wecalculate_money_supply_calculator, title = {Money Supply Calculator — Money Multiplier & M2 Estimate}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/money-supply-calculator}}, year = {2026}, note = {TG we-Calculate} }
Did this calculator help you?