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December 7, 2015

The Long-Run Natural Rate of Interest
Charles T. Carlstrom and Timothy Stehulak

There has been a lot of speculation lately about
whether the natural rate of interest has fallen, and if
so, by how much. There are many related definitions
of the natural rate, but we will define it as the real
(inflation-adjusted) safe interest rate that the economy
will converge to over time. This can be thought of as
the neutral interest rate in the long term, that is, the
real interest rate consistent with the central bank’s
inflation and employment mandates. It is important to
remember that this interest rate is not a policy choice
but instead is governed by factors such as world savings and interest rates, productivity growth, and demographics. We will look at estimates of long-term real
interest rates and the preceding factors.
One way to estimate the natural rate is to take the
long-range federal funds rate projection of Federal
Open Market Committee members as a measure of
the long-term nominal interest rate, and subtract the
Committee’s inflation objective, since it is anchoring
longer-run inflation expectations. In January 2012, the
median forecast of Committee members for the funds
rate in the longer run was 4.25 percent. In September

Survey of Economic Projections: Long-Run
Fed Funds Rate
Fed funds rate
5.0
4.5
4.0
3.5
3.0
2.5
January 2012

September 2015

Source: Board of Governors of the Federal Reserve System.

2015, it had fallen to 3.5 percent, a 75 basis point
decline. Subtracting the Committee’s inflation objective of 2 percent from each of these forecasts means
the long-run real interest rate fell from 2.25 percent to
1.5 percent.
Another way of estimating what real interest rates are
expected to be in the longer run is to calculate what
markets expect them to be on average between five
and ten years from now. We use five- and ten-year
government bonds to estimate the longer-term nominal interest rate, which we then adjust for expected inflation using estimates from a model developed by the
Federal Reserve Bank of Cleveland. This calculation
also suggests a decline in the natural rate of interest.
Prior to 2012 this measure of long-term real interest
rates averaged more than 2 percent. Recently, however, it has averaged less than 1.5 percent. The decline
is around 75 basis points.

Real Five to Ten-Year Forward Rate for
Government Bonds
Real forward rate
3.0
2.5
2.0
1.5
1.0
0.5
2000

2005

2010

2015

Sources: Board of Governors of the Federal Reserve System, Federal Reserve
Bank of Cleveland.

Ten-Year Interest Rate on European Government
Bonds
Average interest rate

One factor that may affect long-run real interest rates
is long-run global interest rates. We see that the
decline in interest rates has not been confined to the
United States. There have been even more dramatic
declines in Germany, France, and the United Kingdom. Before the recession, nominal interest rates in
these countries were around 4 percent. These fell
around 2 percentage points to 2 percent after the start
of the recession, and currently they are even lower,
around 1 percent. Though these figures are not adjusted for inflation expectations, they still suggest that
the natural rate of interest may have fallen in these
countries as well. Lower world-wide interest rates feed
into lower domestic interest rates.
Another factor influencing the real natural rate of
interest is productivity growth. Before the recession, it
averaged 1.4 percent, but since the start of the recession, it has averaged only 0.4 percent—a full percentage point decline. Lower productivity growth depresses the real interest rate, all else equal.
Yet another factor influencing real interest rates is
population growth. Since 2000, population growth has
declined approximately 0.4 percent from 1.1 percent
to 0.7 percent. Lower population growth tends to lower
the real interest rate.

6
5
4
3
2
1
2000

2005

2010

2015

Note: Simple average of 10-year bonds from UK, France, and Germany.
Source: Bloomberg.

Total Factor Productivity Growth
Four quarter percent change
4

2

0

−2

−4
2000

2005

Note: Total factor productivity for business sector.
Source: Federal Reserve Bank of San Francisco.

2010

2015

By every measure we have considered, it appears
that long-term real interest rates have declined. On
average since the recession, this decline is probably in the neighborhood of a full percentage point.
In terms of monetary policy, this result does not bear
so much on the argument about whether or not to
increase interest rates shortly. But it does suggest that
interest rates will increase more gradually than in past
recoveries.

United States Population Growth Rate
Annual growth rate in percent
1.1

1.0

0.9

0.8

0.7
2000

2005

2010

2015

Source: US Census Bureau.

Charles Carlstrom is a senior economic advisor in the Research Department of the Federal Reserve Bank of Cleveland. In this role, he
conducts research and authors articles on monetary economics and public finance.
Timothy Stehulak is a research analyst in the Research Department at the Federal Reserve Bank of Cleveland. His primary interests
include applied microeconomics, economics of education, labor economics, and the regional economy.
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