等額本息還貸,利息是怎麼算的

我在建行貸款127000元，按等額本息還貸，月供1452.38元,為什麼每月只還了770幾元本金,除了扣除利息還有什麼其他費用嗎,請知道的指點指點,非常感謝!!!!

等額本息還款名詞解釋:把按揭貸款的本金總額與利息總額相加,然後平均分攤到還款期限的每個月中。

底下我用1萬用3年期（36個月），按照7.20的利率做個案例算一個給你看，你就會比較明白了。

期數月供月供本金月供利息本金余額
1309.69249.6960.009750.31
2309.69251.1958.509499.13
3309.69252.7056.999246.44
4309.69254.2155.488992.23
5309.69255.7453.958736.50
6309.69257.2752.428479.23
7309.69258.8250.888220.42
8309.69260.3749.327960.06
9309.69261.9347.767698.13
10309.69263.5046.197434.63
11309.69265.0844.617169.55
12309.69266.6743.026902.89
13309.69268.2741.426634.62
14309.69269.8839.816364.74
15309.69271.5038.196093.24
16309.69273.1336.565820.11
17309.69274.7734.925545.35
18309.69276.4233.275268.93
19309.69278.0831.614990.86
20309.69279.7529.954711.12
21309.69281.4228.274429.70
22309.69283.1126.584146.59
23309.69284.8124.883861.79
24309.69286.5223.173575.27
25309.69288.2421.453287.04
26309.69289.9719.722997.07
27309.69291.7117.982705.37
28309.69293.4616.232411.91
29309.69295.2214.472116.70
30309.69296.9912.701819.71
31309.69298.7710.921520.94
32309.69300.579.131220.38
33309.69302.377.32918.02
34309.69304.185.51613.84
35309.69306.013.68307.84
36309.69307.841.8500.00
總計11148.7010000.011148.70--

而且當你的貸款年限越長，一開始的本金和利息比，相差是越大的（本金少，利息多）