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Plagiarism Similarity Percentage Calculator

Work out plagiarism similarity percentage instantly with clear inputs, formula shown and shareable results.

About Plagiarism Similarity Percentage Calculator

A raw similarity index counts every matching string including correctly cited quotations, references and standard phrases, so it always overstates concern. 420 matched words in 6000 is 7% raw, but excluding 180 properly quoted words gives 4% adjusted. No threshold proves misconduct - the passages must be read.

Formulas

Raw similarity

raw = matched words / total words x 100

Adjusted similarity

adjusted = (matched - properly quoted) / total x 100

Worked example

With the default values below, Plagiarism Similarity Percentage Calculator returns Similarity Excluding Quotations of 4.00%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Words matching other sourcesminimum 0
420
Total words in the documentminimum 1
6,000
Words in properly attributed quotationsminimum 0
180

Results

Similarity Excluding Quotations
4.00%
Raw Similarity Index
7.00%
Unattributed Matching Words
240
Assessment
Low - typical of incidental phrase overlap

Step by step

  1. 1Values used
  2. 2Raw similarity
  3. 3Adjusted similarity
  4. 4Similarity Excluding Quotations= 4.00
  5. 5Raw Similarity Index= 7.00
  6. 6Unattributed Matching Words= 240
  7. 7Assessment= Low - typical of incidental phrase overlap

Assumptions and limits

  • The result is derived only from the 3 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.

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

Frequently Asked Questions

Is there a safe similarity percentage?

No. A 30% index of correctly cited material is fine while a 4% index containing one stolen paragraph is not. The number is a pointer, not a verdict.

Why do bibliographies inflate the score?

Because reference lists match other papers citing the same works. Most tools can exclude them, and doing so is standard practice.

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