We are reporting on research and development in the field of thin-layer planar silicon avalanche photodiodes operated as photon counters in a Geiger mode. We have developed and tested a technique, which permits an estimation of the photon number initiated a detection process. It can be applied in a time correlated photon counting experiment simultaneously with originally required time interval estimation. The principal limitation is a using of laser pulse with width below 30 ps to achieve detection concurrent in compare with carrier multiplication speed. The number of photons which triggered the avalanche is estimated on the basis of the effective rise-time difference of the avalanche current. The active quenching and gating circuit provides two uniform electrical pulses, and the time interval between them is related to the number of photons detected. The strong temporal correlation between avalanche start and one of pulses is preserved. Employing the picosecond event timing device, the photon number can be estimated within the dynamical range from 1 up to 1000 photons with the resolution better than a factor of three. The avalanche structure is operated on temperature achievable by thermo-electrical cooling. The applications of presented technique are in any time correlated photon counting (TCPC) measurement where the additional information about signal strength, i.e. statistical number of photons in laser pulse, is interesting. Other applications in the testing of quantum-well-based single photon light sources or squeezed light sources are expected.