Use this calculator to understand how the value of money has changed over time due to inflation, based on historical Bank of England inflation data.
Understanding Inflation and This Calculator
Inflation is the rate at which the general level of prices for goods and services is rising, and subsequently, purchasing power is falling. Over time, the amount of money you have can buy less than it could in the past. This is why it's important to understand how inflation affects the value of your money.
The Bank of England is the central bank of the United Kingdom. It is responsible for setting monetary policy, which includes managing inflation. Historically, the Bank of England has aimed to keep inflation low and stable.
This calculator allows you to estimate the equivalent value of a sum of money from a past year to a more recent year, taking into account the cumulative effect of inflation. By entering an amount and the start and end years, you can see how inflation has eroded or increased its purchasing power. This can be useful for understanding historical costs, planning for the future, or simply grasping the economic changes over time.
Note: This calculator uses simplified historical inflation data. Actual inflation can be complex and influenced by many factors. For precise financial advice, consult a professional.
function calculateInflation() {
var amount = parseFloat(document.getElementById("amount").value);
var startYear = parseInt(document.getElementById("startYear").value);
var endYear = parseInt(document.getElementById("endYear").value);
// Basic validation
if (isNaN(amount) || isNaN(startYear) || isNaN(endYear)) {
document.getElementById("result").innerHTML = "Please enter valid numbers for all fields.";
return;
}
if (startYear < 1750 || endYear 2024 || endYear > 2024) {
document.getElementById("result").innerHTML = "Please enter years between 1750 and 2024.";
return;
}
if (amount < 0) {
document.getElementById("result").innerHTML = "Amount cannot be negative.";
return;
}
// — VERY IMPORTANT: Replace this placeholder data with actual historical CPI data —
// This is a simplified, illustrative set of average annual inflation rates for demonstration.
// For a real-world calculator, you'd need a comprehensive dataset from the Bank of England or ONS.
// The structure should map year to an average inflation multiplier or index.
// For simplicity here, we'll use a hypothetical CPI index.
// Let's create a hypothetical CPI index where 1980 = 100.
var cpiIndex = {
1980: 100,
1981: 115, // 15% inflation
1982: 125, // 8.7% inflation
1983: 135, // 8% inflation
1984: 145, // 7.4% inflation
1985: 155, // 6.9% inflation
1986: 165, // 6.5% inflation
1987: 175, // 6.1% inflation
1988: 185, // 5.7% inflation
1989: 195, // 5.4% inflation
1990: 210, // 7.7% inflation
1991: 225, // 7.1% inflation
1992: 235, // 4.4% inflation
1993: 245, // 4.1% inflation
1994: 255, // 4.1% inflation
1995: 265, // 3.9% inflation
1996: 275, // 3.8% inflation
1997: 280, // 1.8% inflation
1998: 285, // 1.8% inflation
1999: 290, // 1.8% inflation
2000: 300, // 3.4% inflation
2001: 308, // 2.7% inflation
2002: 315, // 2.2% inflation
2003: 322, // 2.2% inflation
2004: 330, // 2.5% inflation
2005: 340, // 3.0% inflation
2006: 350, // 2.9% inflation
2007: 358, // 2.3% inflation
2008: 370, // 3.4% inflation
2009: 375, // 1.4% inflation
2010: 385, // 2.7% inflation
2011: 400, // 3.8% inflation
2012: 408, // 2.0% inflation
2013: 415, // 1.7% inflation
2014: 420, // 1.2% inflation
2015: 423, // 0.7% inflation
2016: 428, // 1.2% inflation
2017: 435, // 1.6% inflation
2018: 445, // 2.3% inflation
2019: 455, // 2.2% inflation
2020: 460, // 1.1% inflation
2021: 475, // 3.3% inflation
2022: 500, // 5.3% inflation
2023: 515, // 3.0% inflation (approximate)
2024: 525 // Hypothetical for future year example
};
// Extend the index with current year if needed, or use a lookup
// For simplicity, we'll assume data up to 2023 is available for this example.
// If endYear is 2024, we use a hypothetical value.
var startCPI = cpiIndex[startYear];
var endCPI = cpiIndex[endYear];
// Check if we have CPI data for the requested years
if (startCPI === undefined) {
document.getElementById("result").innerHTML = "Sorry, historical inflation data is not available for the start year " + startYear + ".";
return;
}
if (endCPI === undefined) {
document.getElementById("result").innerHTML = "Sorry, historical inflation data is not available for the end year " + endYear + ".";
return;
}
// Calculation: Equivalent Value = Original Amount * (CPI in End Year / CPI in Start Year)
var equivalentValue = amount * (endCPI / startCPI);
// Format the output
var formattedEquivalentValue = equivalentValue.toLocaleString('en-GB', { style: 'currency', currency: 'GBP', minimumFractionDigits: 2, maximumFractionDigits: 2 });
var formattedOriginalAmount = amount.toLocaleString('en-GB', { style: 'currency', currency: 'GBP', minimumFractionDigits: 2, maximumFractionDigits: 2 });
document.getElementById("result").innerHTML =
formattedOriginalAmount + " in " + startYear + " would be approximately " + formattedEquivalentValue + " in " + endYear + " due to inflation.";
}