容(rong)積(ji)率又稱建(jian)筑面(mian)(mian)積(ji)毛(mao)密度(du)，是指一(yi)個(ge)小(xiao)區的(de)(de)地(di)上總(zong)建(jian)筑面(mian)(mian)積(ji)與用地(di)面(mian)(mian)積(ji)的(de)(de)比率。對于開發商(shang)來說(shuo)，容(rong)積(ji)率決定(ding)地(di)價(jia)成本在(zai)房屋中占的(de)(de)比例，而(er)對于住戶來說(shuo)，容(rong)積(ji)率直接涉及到居住的(de)(de)舒適(shi)度(du)。容(rong)積(ji)率項目(mu)(mu)用地(di)范圍(wei)內(nei)地(di)上總(zong)建(jian)筑面(mian)(mian)積(ji)(但必須是正負(fu)0標高以上的(de)(de)建(jian)筑面(mian)(mian)積(ji))與項目(mu)(mu)總(zong)用地(di)面(mian)(mian)積(ji)的(de)(de)比值。

容積(ji)(ji)率(lv)是(shi)(shi)衡量(liang)建設用地(di)(di)使用強度(du)(du)的(de)(de)一(yi)項重(zhong)要指標。容積(ji)(ji)率(lv)的(de)(de)值是(shi)(shi)無量(liang)綱的(de)(de)比值，通常以地(di)(di)塊面(mian)(mian)積(ji)(ji)為1，地(di)(di)塊內地(di)(di)上建筑(zhu)(zhu)物的(de)(de)總(zong)建筑(zhu)(zhu)面(mian)(mian)積(ji)(ji)對地(di)(di)塊面(mian)(mian)積(ji)(ji)的(de)(de)倍數，即為容積(ji)(ji)率(lv)的(de)(de)值。附屬建筑(zhu)(zhu)物也(ye)計(ji)算(suan)在(zai)內，但(dan)應(ying)注(zhu)(zhu)明(ming)不計(ji)算(suan)面(mian)(mian)積(ji)(ji)的(de)(de)附屬建筑(zhu)(zhu)物除外(wai)。值得注(zhu)(zhu)意的(de)(de)是(shi)(shi)，容積(ji)(ji)率(lv)越(yue)低(di)，居民的(de)(de)舒適度(du)(du)越(yue)高，反之則(ze)舒適度(du)(du)越(yue)低(di)。

一般情況下指某一基(ji)地(di)(di)(di)(di)范(fan)圍(wei)內，地(di)(di)(di)(di)面(mian)(mian)以(yi)上各類建(jian)筑的建(jian)筑面(mian)(mian)積總和與基(ji)地(di)(di)(di)(di)面(mian)(mian)積的比值。可以(yi)根據(ju)規劃和管理需要對地(di)(di)(di)(di)下建(jian)筑面(mian)(mian)積計(ji)算地(di)(di)(di)(di)下容(rong)(rong)積率(lv)。其實，一直以(yi)來(lai)都(dou)是(shi)(shi)(shi)地(di)(di)(di)(di)方(fang)政府自行規定(ding)的，關于地(di)(di)(di)(di)下室是(shi)(shi)(shi)否(fou)算容(rong)(rong)積率(lv)，地(di)(di)(di)(di)下商業建(jian)筑(商業用(yong)房(fang))算不算容(rong)(rong)積率(lv)都(dou)做了很好(hao)的探(tan)索。不算容(rong)(rong)積率(lv)是(shi)(shi)(shi)考(kao)慮到節約用(yong)地(di)(di)(di)(di)，鼓勵開(kai)發(fa)地(di)(di)(di)(di)下空間，計(ji)入(ru)容(rong)(rong)積率(lv)是(shi)(shi)(shi)規范(fan)房(fang)地(di)(di)(di)(di)產市場，防(fang)止不良房(fang)地(di)(di)(di)(di)產開(kai)發(fa)商有漏洞(dong)可鉆。容(rong)(rong)積率(lv)將直接關系(xi)到建(jian)筑用(yong)地(di)(di)(di)(di)的大小。