Funnily enough, there was a Science article published on this (see here).
In their sample of university students, Mehl et al. had participants wear a specialized device that recorded audio samples from daily life (The EAR). They report that (emphasis mine):
The data suggest that women spoke on average 16,215 (SD = 7301) words and men 15,669 (SD = 8633) words over an assumed period of, on average, 17 waking hours. Expressed in a common effect-size metric (Cohen’s d = 0.07), this sex difference in daily word use (546 words) is equal to only 7% of the standardized variability among women and men. Further, the difference does not meet conventional thresholds for statistical significance (P = 0.248, one-sided test). Thus, the data fail to reveal a reliable sex difference in daily word use. Women and men both use on average about 16,000 words per day, with very large individual differences around this mean.
Although, it's possible that we might see systematic differences depending on factors other than sex (e.g., SES, age).
References
- Mehl, M. R., Vazire, S., Ramírez-Esparza, N., Slatcher, R. B., & Pennebaker, J. W. (2007). Are women really more talkative than men?. Science, 317(5834), 82-82.