Calcz

World Index Comparison Calculator

This calculator lets you compare seven major global stock indices side by side, backtested with real weekly price data from roughly 1999 to the present. Choose a home currency, pick a lump sum (and optionally a monthly contribution), and see how each index would have grown, converted into your chosen currency.

The tool is a backtest, not a forecast. It replays the actual weekly closes of each index, including the dot-com crash of 2000-2002, the 2008 financial crisis, the 2020 pandemic drop, and the 2022 rate shock.

Which indices are included?

The calculator covers seven widely tracked markets:

  • S&P 500 (United States): the 500 largest US companies by market capitalisation, widely used as a proxy for US equities
  • FTSE 100 (United Kingdom): the 100 largest companies listed on the London Stock Exchange
  • Nikkei 225 (Japan): 225 blue-chip companies traded on the Tokyo Stock Exchange
  • CAC 40 (France): 40 of the largest French companies, a benchmark for the eurozone's second-largest economy
  • Hang Seng (Hong Kong): the main index for the Hong Kong stock exchange, with heavy exposure to mainland Chinese businesses
  • S&P/TSX Composite (Canada): the major Canadian equity benchmark, with significant weight in energy, financials, and materials
  • S&P/ASX 200 (Australia): the 200 largest companies listed on the Australian Securities Exchange

Germany's DAX is not included in version one of this tool, though it may be added in a future update.

Data sources

Index prices come from Yahoo Finance (weekly Friday closing prices, price index). FX conversion rates are drawn from the European Central Bank euro reference rates, which cover EUR/USD, EUR/GBP, EUR/JPY, EUR/HKD, EUR/CAD, and EUR/AUD cross rates back to 1999. For indices priced in a non-EUR currency, the conversion is done via the EUR cross rates.

Data history starts at approximately the first week of 1999 for most indices. All indices share a common window, trimmed to the earliest Friday where every selected index has a valid price, so the comparison is always over the same period.

Dividends

The source data are price indices, not total-return indices, so dividends are not captured directly in the weekly closes. To make comparisons fairer, the calculator applies a uniform approximate dividend add-back: each index is assigned a long-run average dividend yield estimate, and that yield is reinvested weekly into the index. This is an approximation. Real dividends vary quarter to quarter, and actual reinvestment tax treatment differs by country and investor type. The "dividends reinvested" toggle lets you switch this add-back on or off so you can see the effect.

Currency effect

The same index can produce very different returns depending on your home currency, because each index is priced in its local currency, and exchange rates shift independently of prices. A UK investor holding the S&P 500 over a period when the dollar fell against sterling would earn less in GBP terms than the dollar return suggests. Conversely, dollar weakness can amplify returns for US investors holding overseas indices.

The calculator converts each weekly index value from its local currency into your chosen home currency (USD, GBP, or EUR) using the ECB rates for that week. This means the chart reflects the total currency-adjusted return a home-currency investor would have seen, not just the index's own-currency performance.

Inflation adjustment

Toggling inflation adjustment converts all values into real (constant) purchasing-power terms using the home currency's CPI. This makes it easier to see what a return actually bought, rather than what it nominally accumulated. Nominal returns look larger, but a portion of any gain is simply keeping pace with rising prices; real returns strip that out.

How the backtest works

  1. On each Friday from the start week to the present, the calculator knows the local-currency close of every selected index and the ECB cross-rates for that week.
  2. Your lump sum is converted from the home currency into units of each index at week one. Monthly contributions buy additional units at each monthly interval.
  3. At every subsequent weekly close, each holding is revalued in home-currency terms: local-currency price multiplied by that week's FX rate.
  4. If dividends reinvested is on, the weekly fraction of the annual yield estimate is credited as additional units at each weekly step.
  5. The final chart plots all selected indices on the same axis, with the winner labelled.

The compound annual growth rate (CAGR) shown for each index is calculated over the full backtested window.

Limitations

  • Approximate dividends. Per-index yield estimates are fixed long-run averages, not actual historical quarterly payouts. Real dividend histories would require licensed total-return index data for each market.
  • History starts around 1999. ECB reference rates in the standard public dataset begin in January 1999. Some index data from Yahoo Finance may be missing for a handful of weeks, particularly around market holidays, and those gaps are filled by carrying the previous close forward.
  • Germany not included. The DAX is a total-return index (dividends already inside the price), which would make a like-for-like dividend add-back comparison with the other price indices misleading. It is excluded from version one to keep the methodology consistent.
  • No taxes or fees. Index fund products tracking these benchmarks charge ongoing fees (typically 0.05% to 0.25% per year) and may distribute dividends differently. Tax on dividends and capital gains varies by jurisdiction and is not modelled.
  • Past performance is not a guide to future results. A period of strong returns for one index may or may not repeat, and a 25-year backtest says nothing certain about the next 25 years.

How to use it

  1. Select the indices you want to compare. You can pick between two and four of the seven at a time, so the chart stays readable.
  2. Choose your home currency (USD, GBP, or EUR). This controls which FX rates are used and how results are formatted.
  3. Set a lump-sum amount, and optionally a regular monthly contribution.
  4. Toggle dividends reinvested and inflation adjustment to taste.
  5. Read the final values and CAGR from the summary row, or explore the chart to see how relative performance shifted through crashes and recoveries.

Comparing a global spread of markets over the same period quickly shows how much home-market bias can cost, and how dramatically currency moves amplify or dampen returns across borders.