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Inflation calculator (future cost and purchasing power)

Calculate what a purchase will cost after inflation, what your money will still buy, and your real return after inflation.

Cập nhật Ví dụ đã kiểm tra: 4

$
%
%
Used for the real return; enter 0 for cash kept at home
Thử
Future cost of the same purchase
$
Future cost of the same purchase: $1,343.92
Số chữ số thập phân: 2; Gần nhất; nếu cách đều thì về chữ số chẵn
What the amount will buy, in today's money
$744.09
Purchasing power lost
25.59%
Total price rise
34.39%
Real return (per year)
2.9126%
Savings at that return, in today's money
$1,332.56
Assumes the same inflation rate every year; actual price indices move unevenly and differ by basket and country.

At 3% inflation, what costs $1,000.00 today costs $1,343.92 in 10 years, and $1,000.00 kept as cash buys only $744.09 worth of today's goods. Earning 6% beats inflation: the real return is 2.913% a year.

Prices and purchasing power

$800$1,000$1,2000246810YearsToday
Cost of the purchaseBuying power of the amountSavings in today's money
Year by year Số hàng: 10
NămCost of the purchaseBuying power of the amountSavings (nominal)Savings (today's money)
1$1,030.00$970.87$1,060.00$1,029.13
2$1,060.90$942.60$1,123.60$1,059.10
3$1,092.73$915.14$1,191.02$1,089.95
4$1,125.51$888.49$1,262.48$1,121.69
5$1,159.27$862.61$1,338.23$1,154.37
6$1,194.05$837.48$1,418.52$1,187.99
7$1,229.87$813.09$1,503.63$1,222.59
8$1,266.77$789.41$1,593.85$1,258.20
9$1,304.77$766.42$1,689.48$1,294.84
10$1,343.92$744.09$1,790.85$1,332.56
Cách tính S

  1. Price growth factor

    (1+π)n=(1+0.03)10=1.343916379(1+\pi)^{n} = (1+0.03)^{10} = 1.343916379

  2. Future cost

    1,000.00×1.343916379=1,343.921{,}000.00 \times 1.343916379 = 1{,}343.92

  3. Purchasing power of the same amount

    1,000.001.343916379=744.09\frac{1{,}000.00}{1.343916379} = 744.09

  4. Real return (Fisher)

    1+0.061+0.03−1=2.9126%\frac{1+0.06}{1+0.03} - 1 = 2.9126\%

    The exact Fisher relation; the shortcut nominal − inflation overstates the real rate slightly.

Giới thiệu Inflation calculator (future cost and purchasing power)

Inflation raises prices by a percentage each year, and it compounds like interest. At a steady rate π, a purchase costing A today costs A(1 + π)^n after n years, and cash held for n years buys only A ÷ (1 + π)^n of today's goods. The real return on savings follows Irving Fisher's relation: (1 + nominal rate) ÷ (1 + inflation) − 1.

With the defaults, 1,000 and 3% inflation for 10 years, the same purchase will cost 1,343.92 and cash of 1,000 will buy 744.09 of today's goods, a 25.59% loss of purchasing power. Savings earning 6% have a real return of 2.9126% a year, not 3%, and grow to 1,332.56 in today's money.

The inflation rate is held constant. Official price indices such as the US CPI-U move unevenly and differ by basket and country, so for past prices use the index values themselves, for example through the BLS CPI inflation calculator.

Ví dụ có lời giải

1,000 at 3% inflation for 10 years, savings at 6%

Amount today
1000
Inflation rate (per year)
3%
Năm
10
Return on savings (per year)
6%
Future cost of the same purchase
1,343.92
What the amount will buy, in today's money
744.09
Purchasing power lost
25.59%
Real return (per year)
2.9126%
Savings at that return, in today's money
1,332.56

Nguồn đối chiếu: Python decimal: 1000·1.03^10 = 1343.9164; 1000/1.03^10 = 744.0939; 1.06/1.03 − 1 = 2.912621 %

Zero inflation

Amount today
1000
Inflation rate (per year)
0%
Năm
10
Return on savings (per year)
6%
Future cost of the same purchase
1,000.00
Purchasing power lost
0.00%
Real return (per year)
6.0000%
Savings at that return, in today's money
1,790.85

Nguồn đối chiếu: With π = 0 the real rate equals the nominal rate; 1000·1.06^10 = 1790.8477 (Python decimal)

Deflation of 2% for 5 years

Amount today
100
Inflation rate (per year)
-2%
Năm
5
Return on savings (per year)
1%
Future cost of the same purchase
90.39
What the amount will buy, in today's money
110.63
Real return (per year)
3.0612%

Nguồn đối chiếu: Python decimal: 100·0.98^5 = 90.3921; 100/0.98^5 = 110.6292; 1.01/0.98 − 1 = 3.0612 %

50,000 at 6.5% for 20 years

Amount today
50,000
Inflation rate (per year)
6.5%
Năm
20
Return on savings (per year)
8%
Future cost of the same purchase
176,182.25
Total price rise
252.36%
Real return (per year)
1.4085%

Nguồn đối chiếu: Python decimal: 50000·1.065^20 = 176182.2532; 1.08/1.065 − 1 = 1.40845 %

Câu hỏi

How do you calculate the future cost of something with inflation?

Multiply today's price by (1 + inflation rate) raised to the number of years. At 3% a year, something costing 1,000 today costs 1,000 × 1.03^10 = 1,343.92 in 10 years, a total price rise of 34.39%. At 3.4% a year it would cost 1,397.03.

How do you calculate the real rate of return after inflation?

Divide (1 + nominal return) by (1 + inflation) and subtract 1, the Fisher relation. Savings earning 6% while prices rise 3% have a real return of 1.06 ÷ 1.03 − 1 = 2.9126% a year. The shortcut 6% − 3% = 3% overstates it slightly, and the gap grows with higher rates.

What is the current US inflation rate?

US consumer prices (CPI-U) rose 3.4% in the 12 months to August 2026, and 2.4% excluding food and energy, according to the Bureau of Labor Statistics. The Federal Reserve's target is 2% a year, measured by the PCE price index rather than the CPI; the Bank of England and the European Central Bank also target 2%.

How long does it take inflation to halve the value of money?

ln 2 ÷ ln(1 + inflation rate) years. At 2% inflation cash loses half its purchasing power in 35.0 years, at 3% in 23.4 years and at 3.4% in 20.7 years. Even at a 2% target rate, 1,000 held as cash for 10 years loses 17.97% of what it can buy.

“Inflation calculator (future cost and purchasing power)” chính xác đến mức nào?

Độ chính xác phụ thuộc vào dữ liệu nhập và giả định của phương pháp. Phép tính thập phân dùng 50 chữ số có nghĩa, nhưng ước lượng, phương pháp số và dữ liệu nguồn có thể kém chính xác hơn; làm tròn khi hiển thị không loại bỏ các giới hạn đó. Ví dụ có lời giải đã đối chiếu với nguồn độc lập: 4. Ví dụ, “1,000 at 3% inflation for 10 years, savings at 6%” được kiểm tra bằng Python decimal: 1000·1.03^10 = 1343.9164; 1000/1.03^10 = 744.0939; 1.06/1.03 − 1 = 2.912621 %.

Phương pháp này lấy từ đâu?

U.S. Bureau of Labor Statistics — CPI inflation calculator; Fisher, I. — The Theory of Interest (1930), real vs nominal rates.

Về công cụ tính này

Future cost=A(1+π)n,Purchasing power=A(1+π)n,rreal=1+i1+π−1\text{Future cost} = A(1+\pi)^{n},\quad \text{Purchasing power} = \frac{A}{(1+\pi)^{n}},\quad r_{\text{real}} = \frac{1+i}{1+\pi} - 1

Nguồn

  1. U.S. Bureau of Labor Statistics — CPI inflation calculator
  2. Fisher, I. — The Theory of Interest (1930), real vs nominal rates

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