WhitmanTrading

What Inflation Does to Savings

Inflation is a fall in what money buys rather than a rise in prices, and it compounds the way interest does. At 3% a year the effect is large enough that savings held in cash lose more than a third of their purchasing power inside two decades.

How it works

Inflation is usually described as prices going up. It is more useful to describe it as money buying less. The two are the same event, but the second framing puts the change where it actually happens — in the money you already hold.

And it compounds. Each year’s fall applies to what is left after the previous year’s, exactly like compound interest running in reverse.

The measurement

One unit of money, held as cash, at three rates:

Rate After 10 years After 20 years After 30 years
2% $0.82 (−18%) $0.67 (−33%) $0.55 (−45%)
3% $0.74 (−26%) $0.55 (−45%) $0.41 (−59%)
5% $0.61 (−39%) $0.38 (−62%) $0.23 (−77%)

At a modest 3%, holding cash for thirty years loses 59% of its purchasing power. No statement ever shows that loss. The balance is unchanged; the thing it buys is not.

The gap between the rows is the part worth noticing. Two percentage points of inflation is the difference between keeping 55 cents and keeping 23 cents over the same thirty years.

Cash is therefore not a neutral position. It is a position with a small, reliable negative real return, which is a very different thing from doing nothing.

In practice: the real return

Subtract inflation from every return you are quoted. A savings account paying 2% in a 3% year is losing 1% a year in the only terms that matter. A 5% return in the same year is a 2% real return.

Standing still requires earning the inflation rate. That is the hurdle every savings decision clears or fails, and it is why “keeping money safe” and “keeping money” are not the same instruction.

Income adjusts late. Prices move continuously and pay reviews happen annually at best, so the gap opens first and closes afterwards, if it closes.

One thing it helps: fixed-rate debt. A mortgage fixed at a set payment is repaid in money worth less each year, so inflation transfers value from the lender to the borrower. That is the only place on this page where the arithmetic runs in your favor, and it applies only to fixed rates.

Over a retirement-length horizon, this is frequently the biggest single factor. Larger than the fee, larger than most of the return difference between reasonable strategies, and almost never modeled by the people it affects most.

Bar diagram of real returns in a 3% inflation year: savings at 2% lose 1%, a 5% return gains 2%.
A diagram of this page's real-return arithmetic.

What inflation is not

It is not the headline rate. The published figure describes an average basket. Your rate depends on what you actually buy — rent, energy, food and healthcare move differently from the average, and frequently faster.

It is not the same as a price rise. A single item getting more expensive is a price change. Inflation is the general fall in what money buys, and confusing the two makes it look like a series of unrelated annoyances.

It is not a reason to avoid cash entirely. An emergency fund buys certainty, and paying a small real cost for certainty is a reasonable trade — as long as it is a trade you made deliberately.

And it is not always positive. Prices can fall too, which sounds pleasant and is generally worse: it makes debt heavier in real terms and gives everyone a reason to postpone spending.

How this connects

The headline figure usually comes from the consumer price index, a weighted basket that may differ a great deal from any one household’s spending.

Cash-like holdings narrow the gap without closing it. A treasury bill, a certificate of deposit or a money market fund typically pays close to prevailing short rates, which can sit above or below inflation depending on where central banks are in the cycle.

Longer money needs assets that can grow. Stocks, an index fund or dividend growth holdings have historically outpaced inflation over long periods, while a bond with a fixed coupon loses real value when prices rise faster than expected, and more so the longer its bond duration.

Real assets are the traditional hedge. Real estate rents tend to rise with prices, and gold or bullion is held for the same reason, though neither tracks inflation closely year to year.

The time horizon decides the mix. Asset allocation for money needed next year differs from money for a retirement account decades away.

Retirement planning builds it in. A safe withdrawal rate is normally adjusted for inflation each year, and social security in the US is indexed to it.

The rule of seventy-two runs in reverse here, estimating how quickly prices double.

And budgeting in real terms is the habit that keeps the whole problem visible.

When it fails to be noticed

The characteristic failure is that nothing happens. No alert fires, no balance falls, no statement shows a loss. The account looks exactly as it did, which is why this is the easiest financial risk to carry for a decade without noticing.

The second failure is not resizing anything. A buffer built to cover six months of costs covers fewer months every year unless it is topped up, and the same applies to any target expressed in a fixed sum.

A third is comparing across decades without adjusting. A salary, a house price or a portfolio value from twenty years ago is not comparable to today’s figure, and most casual comparisons of that kind are measuring inflation rather than progress.

And a fourth is treating a nominal gain as a gain. An account up 3% in a 3% year has made nothing, and the tax is charged on the 3% regardless — which is covered on taxes on trading.

That last one deserves spelling out, because it is the least intuitive. Tax is charged on nominal gains in most systems, so in a high-inflation year an investor can pay real tax on a gain that was not real. The account grew in dollars, lost ground in groceries, and still generated a bill.

The practical response to all of this is short. Hold cash for the job cash does — the buffer, and money with a date on it — and expect the rest to at least clear inflation. Restate long-horizon targets in today’s money rather than in a fixed future sum, and revisit any figure you set more than a few years ago. None of that requires a forecast; it only requires applying the table above to numbers you already have.

The original data

3 of the 24,971 videos measured for this site name inflation in the title, at a median of 707,096 views. Three videos, a very high median, and a topic that quietly determines whether every other number on this site means anything.

The question: Savings pays two percent, prices rise three. Hold cash?

The purchasing-power figures were computed for this page — a unit of money divided by compounding inflation at 2%, 3% and 5% over ten, twenty and thirty years. They are arithmetic rather than a forecast, and the reason to publish them is that almost nobody carries the 30-year number in their head.

Compound interest is the same mechanism working for you. The emergency fund is the cash position this page is really about. And net worth is the figure that should be read in real terms rather than nominal ones.

What I actually do

I re-check the size of an emergency fund against current prices rather than against the figure it was set up with. A fund built to cover a set number of months quietly covers fewer of them as prices rise. The months are the target, not the balance.

— Michael Whitman

This page is educational, not financial advice. Test every idea on your own charts before risking money.