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Margin Of Victory Calculator

Work out margin of victory instantly with clear inputs, formula shown and shareable results.

About Margin Of Victory Calculator

Margin of victory as a percentage of valid votes is the standard measure of how safe a seat is, and it determines how much swing is needed to flip it. The winner's share of the total electorate is a separate and often sobering figure, since it accounts for non-voters.

Formulas

Margin

Margin = Winner's votes - Runner-up's votes

Margin percentage

Margin % = Margin / Total valid votes x 100

Worked example

With the default values below, Margin Of Victory Calculator returns Margin of victory of 6.23%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Winner's votes
486,200
Runner-up's votes
412,700
Total valid votes
1,180,000
Registered electors
1,850,000

Results

Margin of victory
6.23%
Margin in votes
73,500
Winner's share of the full electorate
26.28%
Seat classification
Competitive

Step by step

  1. 1Values used
  2. 2Margin
  3. 3Margin percentage
  4. 4Margin of victory= 6.23
  5. 5Margin in votes= 73,500
  6. 6Winner's share of the full electorate= 26.28
  7. 7Seat classification= Competitive

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Indicative estimate only. Fees, entitlements, limits and formulas vary by jurisdiction, statute, policy wording and the facts of the case. This is not legal, tax, insurance or financial advice — confirm with a qualified professional or the relevant authority.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Indicative estimate only. Fees, entitlements, limits and formulas vary by jurisdiction, statute, policy wording and the facts of the case. This is not legal, tax, insurance or financial advice — confirm with a qualified professional or the relevant authority.

Frequently Asked Questions

How much swing flips a seat?

Roughly half the margin percentage, since a swing moves votes from one party to the other and counts in both directions.

What counts as a marginal seat?

Conventionally a margin under 5% of valid votes, though analysts use anything from 3% to 10% depending on the system.

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