Vocabulary Growth Rate Calculator
Calculate your vocabulary growth rate — how many new words you're learning per day, week, or month — and project future vocabulary size.
Formulas Used
1. Absolute Growth:
New Words = Vt − V0
2. Linear Growth Rate:
Rate = (Vt − V0) / t (words per day)
3. Percentage Growth Over Period:
Growth% = ((Vt − V0) / V0) × 100
4. Compound Annual Growth Rate (CAGR):
CAGR = (Vt / V0)1/tyears − 1
5. Continuous Growth Rate:
r = ln(Vt / V0) / tyears
6. Projection (Compound Model):
Vproj = Vt × erdaily × d
where rdaily = ln(Vt / V0) / tdays
Assumptions & References
- The continuous growth rate uses the natural logarithm model: r = ln(Vt/V0) / t, standard in population and learning growth models.
- Reference: Nation, I.S.P. & Waring, R. (1997). Vocabulary size, text coverage and word lists. In N. Schmitt & M. McCarthy (Eds.), Vocabulary: Description, Acquisition and Pedagogy. Cambridge University Press.