How to translate "evaluate, estimate" [time for smt.]? There are lots of synonims in Chinese for &quot;evaluate, estimate&quot;, so my question is: what is the best match for &quot;evaluate/estimate time needed for something&quot;
E.g.

I want to estimate how long it will take me to prepare for examination.
我要 [评定] 准备好去应考需要多少时间。


UPDATE (15.01.2018)
Till now there are four answers and comments and all of them give different versions:

@Diaph - 估计 or 评估 (我想要[评估]准备应考需要多少时间?)
@user6065 - 计算、估算，琢磨
@Pedroski - 预测 (我想预测准备这场考试要多长时间。)
@dan - 预估 (我想预估一下我要花多长时间来备考。)

So please provide some prove or explanation why this translation is used in your answer.

UPDATE (some examples from internet; English translation is mine):
估计 [gūjì] is mostly used as a noun:

时间估计能准确一些 (Time estimation could be more precise)

But also:

估计备份处理时间 (Estimate backup processing time)
正在估计时间 (Estimating time...)
I want to estimate how long it will take me to prepare for examination


In this case, I will use 预估. 
我想预估一下我要花多长时间来备考。 备考 is short for 准备考试.