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Reading Level (Lexile Estimate) Calculator

Work out reading level (lexile estimate) instantly with clear inputs, formula shown and shareable results.

About Reading Level (Lexile Estimate) Calculator

The published Lexile theoretical logit combines sentence length and word frequency, then is rescaled by 180.1295 and shifted by -366.5714 to land on the Lexile scale. Lexile ranks text by two measurable properties rather than subject matter, which is why it can rate a short-sentence science text as easier than a long-sentence picture book.

Formulas

Theoretical logit

logit = 9.82247 x ln(mean sentence length) - 2.14634 x mean log word frequency

Lexile measure

Lexile = logit x 180.1295 - 366.5714, reported to the nearest 5L

Worked example

With the default values below, Reading Level (Lexile Estimate) Calculator returns Estimated Lexile measure of 2,640. Change any input above and every figure here is recalculated in your browser.

Inputs used

Mean sentence lengthminimum 1 words
12 words
Mean log word frequencyminimum 0.1
3.6

Results

Estimated Lexile measure
2,640 L
Typical reader band
Upper secondary and above
Theoretical logit
16.6811
Unrounded measure
2,638.2

Step by step

  1. 1Values used
  2. 2Theoretical logit
  3. 3Lexile measure
  4. 4Estimated Lexile measure= 2,640 L
  5. 5Typical reader band= Upper secondary and above
  6. 6Theoretical logit= 16.6811
  7. 7Unrounded measure= 2,638.2

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax or fees or charges into account.
  • Figures are rounded for display to 4 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

How is the Reading Level (Lexile Estimate) figure worked out?

logit = 9.82247 x ln(mean sentence length) - 2.14634 x mean log word frequency. The published Lexile theoretical logit combines sentence length and word frequency, then is rescaled by 180.1295 and shifted by -366.5714 to land on the Lexile scale.

Why does this matter?

Lexile ranks text by two measurable properties rather than subject matter, which is why it can rate a short-sentence science text as easier than a long-sentence picture book.

What do I need to enter?

Enter mean sentence length, mean log word frequency. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.

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