ABSTRACT This study compares the fracture parameters of self-compacting lightweight concrete (SCLC) obtained from two-parameter model (TPM) and size effect method (SEM). Moreover, the influence of using silica fume and nano-silica on the fracture parameters and mechanical properties of SCLC was evaluated. For this purpose, eight mix designs were made by replacing 0, 1, 3, and 5% of the cement weight with nano-silica and using 0 and 10% of the cement weight with silica fume. The SCLC incorporating 3% nano-silica and 10% silica fume was the best mix design. This mix enhanced the compressive strength, tensile strength, and elasticity modulus of SCLC by about 36, 17, and 18%, respectively. Based on SEM, this mix increased the fracture energy and fracture toughness by about 32% and 25%, respectively. According to TPM, this mix improved the mentioned parameters by approximately 33 and 25%, respectively. The average value of differences in the fracture energy and fracture toughness attained from SEM and TPM were about 2% and 1%, respectively. The average difference in the critical crack tip opening displacement (CTODc) results was about 6%.