The paper presents results from an experiment focused on the establishment of total grass biomass amount grown in the house garden during the growing season and volume of the domestic composter required for biomass treatment.Grass in the experimental part of the garden (area 43.75 m2) was cut at regular intervals (1x2 weeks) during the growing season. The cut green biomass was mixed with wood shavings at a volume ratio of 3:1 and the mixed material was placed inside a home composter (volume 300 dm3). During the composting process, the blended biomass was mixed and aerated for 1x4 weeks.The total amount of grass biomass from the experimental plot was 44.8 kg; the amount of added wood shavings was 13.9 kg. The total volume of raw mixture (fresh) was nearly 370 dm3 but due to the composting process during the growing season, the volume of composted raw materials was reduced at the end of the growing season to about 168 dm3.The measured and calculated values show that the composter volume required for the treatment of grown-up and cut grass biomass per 1m2 of garden lawn is 3.83 dm3. Due to fluctuations of grass biomass production in individual years, it is recommended to increase the required composter volume to 4 dm3 per 1m2 of garden lawn.