**Table 2:** Filling factors of the chromospheres for the modelled stars and the parameters used to calculate the filling factors. The measured scaling factor $f_{\rm m}$ between model and flux calibrated spectrum is given as well as the theoretical scaling factor $f_{\rm th}= R^{2}/d^{2}$ .
Star	$\log L_{\rm bol}$	Radius [cm]	distance [pc]	$f_{\rm m}$	$f_{\rm th}$	Filling factor
AD Leo	31.94 ¹	$3.4 \times 10^{10}$	4.9 ¹	$3.0 \times 10^{-26}$	$5.3 \times 10^{-26}$	0.57
YZ CMi	31.69 ¹	$2.9 \times 10^{10}$	6.1 ¹	$1.7\times 10^{-26}$	$2.5 \times 10^{-26}$	0.68
CN Leo	30.55 ¹	$8.4 \times 10^{9}$	2.4 ¹	$0.7\times 10^{-26}$	$1.4 \times 10^{-26}$	0.50
DX Cnc	30.48 ¹	$8.9 \times 10^{9}$	3.6 ¹	$1.7\times 10^{-27}$	$6.6\times 10^{-27}$	0.26
LHS 3003	30.31 ²	$8.5 \times 10^{10}$	6.4 ³	$0.5\times 10^{-27}$	$1.9 \times 10^{-27}$	0.26

$\textstyle \parbox{12.5cm}{ $^{1}$\space \citet{Delfosse}, $^{2}$\space \citet{Leggett}, $^{3}$\space \citet{Dahn}.}$

	1 Introduction
	2 Observations and data analysis
	3 Model construction and calculation
	4 The influence of the model parameters
	5 Results
	6 Discussion
	7 Summary and conclusion
	References
	Online Material
	Appendix A: Identification of chromospheric emission lines