Skip to content
marketsetupsdesk.online / Resources
Practical market worksheet

Compounded Return Series Calculator

See how a sequence of supplied percentage returns compounds into an index.

Your inputsBrowser calculationCSV export

Starting at a hypothetical index of 100, +10% produces 110, −10% produces 99, and +5% produces 103.95. Cumulative return is +3.95%. The arithmetic average is about 1.6667% per period, while the geometric average is about 1.2997%; the two averages describe different calculations.

What this helps you check

Averaging percentage returns does not reproduce the change in wealth. This worksheet multiplies each period's growth factor, follows an index from your chosen starting level, and reports cumulative return alongside arithmetic and geometric period averages.

These means use the periods you supply and are not automatically annualized. A −100% period sends the index to zero; later percentage returns relative to zero do not define a recovery. Returns below −100% are outside this nonnegative-wealth index model.

Your worksheet

No account connection required

Inputs are processed in your browser by this calculator. There is no quote lookup or file upload for the calculation. Site measurement and consent are handled separately by the site's privacy and consent controls.

CSV schema: period (text), return_pct (number). Header required; comma delimiter. Numeric fields use decimal points. Timestamps require Z or a numeric UTC offset. The original input remains unchanged.

Unit: index. Use a decimal point; do not use thousands separators.
Comma-separated CSV with a header. Maximum 500 rows and 200,000 characters.

Interactive calculation requires JavaScript. The method and hypothetical worked example below remain readable.

Hypothetical worked example

Check the example by hand

Starting at a hypothetical index of 100, +10% produces 110, −10% produces 99, and +5% produces 103.95. Cumulative return is +3.95%. The arithmetic average is about 1.6667% per period, while the geometric average is about 1.2997%; the two averages describe different calculations.

Ending index
103.95index
Compounded return
3.95%
Arithmetic mean
1.66666666667% per period
Geometric mean
1.29970125041% per period
Exact example inputs
{
  "starting_index": "100",
  "csv": "period,return_pct\n1,10\n2,-10\n3,5"
}

The example is invented to demonstrate the method. It is not a current market quote, a provider's fee schedule or verified trading performance.

How the worksheet works

  1. factor_i=1+return_pct_i/100; reject returns<-100%.
  2. ending_index=starting_index*product(factor_i).
  3. compounded_pct=100*(product(factors)-1); arithmetic_mean=sum(return_pct)/n.
  4. geometric_mean_pct=100*(product(factors)^(1/n)-1).
  5. For a -100% row the index reaches zero; warn that later returns relative to zero are not defined. Retain zero compounded wealth rather than implying recovery.

These means use the periods you supply and are not automatically annualized. A −100% period sends the index to zero; later percentage returns relative to zero do not define a recovery. Returns below −100% are outside this nonnegative-wealth index model.

Boundaries to keep in view

  • Periods must use the same definition and externally supplied returns must already treat cash flows correctly.
  • No annualization, forecast or recommended return target.
  • Do not interpret raw deposits as period return.

Compare resources for this task

A return-series review starts with period and cash-flow definitions. Record tools, chart exports and spreadsheets can support analysis, but the sequence should not be inferred merely from a chart's visual slope or scale.

10 Services for Reviewing Return Series

Official sources and scope

The sources document formats, mechanisms or record workflows. The arithmetic and editorial comparison on this page use the supplied worksheet definitions.

  • Microsoft Excel CSV import/export

    CSV import/export and explicit column interpretation; opening CSV applies default formats.

    Reference checked 2026-10-01. Consult the source for current product rules.
  • Google Sheets data ingestion

    CSV ingestion and spreadsheet analysis; file size and format limitations apply.

    Reference checked 2026-10-01. Consult the source for current product rules.
  • TraderSync trade file import

    Trade file imports with explicit date format and time zone.

    Reference checked 2026-10-01. Consult the source for current product rules.