A study was conducted from 15th December 2019 to 25th January 2020 at Birendranagar Municipality- 12, Surkhet to determine the effect of phytase on the feed intake, growth performance and economics in cobb 500 broilers. Combined brooding was done for 10 days and then the chicks were separated into different treatments. A total of 288 broiler chicks were allocated to six different treatment groups. The experimental design was Completely Randomized Design (CRD), each treatment with four replications. And each replication had 12 birds in it. The birds in six treatments were fed with isoproteinous and isocaloric diet containing different level of phytase and wheat. T0 was the control diet containing basal diet, T1 consisted of basal diet and phytase (0.75gm/100 kg feed), T2 consisted of basal diet containing wheat (13%), T3 consisted of basal diet containing wheat (13%) and phytase (0.75gm/100 kg feed), T4 consisted of basal diet containing wheat (26%), T5 consisted of basal diet containing wheat (26%) and phytase (0.75gm/100 kg feed). Weekly average body weight, weight gain, feed consumption and feed efficiency were recorded for four weeks after the birds were allocated to different treatments. All the data recorded was statistically analyzed for Completely Randomized Design (CRD). The result showed that the overall weekly feed consumption was recorded higher (1.30 ± 0.0423 Kg) in the birds of treatment group T5. On the other significantly (P<0.01) higher (2688.46 ± 7.99 gm) cumulative live weight was recorded for the birds of treatment group T3. Likewise mean weekly weight gain was significantly (P<0.01) higher (293.53 ± 21.85 gm/week/bird) in treatment group T3 in the 1st week, significantly (P<0.05) higher (548.57 ± 4.06 gm/week/bird) in T1 in 2nd week, significantly (P<0.01) higher (649.23 ± 21.32 gm/week/bird) in T3 in 3rd week and significantly (P<0.01) higher (1122.65 ± 30.90 gm/week/bird) in T0 in 4th week. The overall FCR was significantly (P<0.01) better (1.94 ± 0.075) in the birds of treatment group T3. The benefit cost ratio was found to be highest (1.3916) from the birds in the treatment group T3. From the results of the experimental trial, it can be concluded that feed used in treatment group T3 helped in better performance and higher benefit cost ratio. Thus, 75 gm phytase in 100 kg of feed (with 13% wheat) can be safely used in the feed of broiler.