| singular | plural |
| Infinitive | | |
| underestimate | |
| present simple | | |
| 1 | I underestimate | we underestimate |
| 2 | you underestimate | you underestimate |
| 3 | he/she/it underestimates | they underestimate |
| past simple | | |
| 1 | I underestimated | we underestimated |
| 2 | you underestimated | you underestimated |
| 3 | he/she/it underestimated | they underestimated |
| future simple | | |
| 1 | I will/shall underestimate | we will/shall underestimate |
| 2 | you will/shall underestimate | you will/shall underestimate |
| 3 | he/she/it will/shall underestimate | they will/shall underestimate |
| conditional simple | | |
| 1 | I would underestimate | we would underestimate |
| 2 | you would underestimate | you would underestimate |
| 3 | he/she/it would underestimate | they would underestimate |
| present continuous | | |
| 1 | I am underestimating | we are underestimating |
| 2 | you are underestimating | you are underestimating |
| 3 | he/she/it is underestimating | they are underestimating |
| past continuous | | |
| 1 | I was underestimating | we were underestimating |
| 2 | you were underestimating | you were underestimating |
| 3 | he/she/it was underestimating | they were underestimating |
| future continuous | | |
| 1 | I will be underestimating | we will be underestimating |
| 2 | you will be underestimating | you will be underestimating |
| 3 | he/she/it will be underestimating | they will be underestimating |
| conditional continuous | | |
| 1 | I would be underestimating | we would be underestimating |
| 2 | you would be underestimating | you would be underestimating |
| 3 | he/she/it would be underestimating | they would be underestimating |
| present perfect | | |
| 1 | I have underestimated | we have underestimated |
| 2 | you have underestimated | you have underestimated |
| 3 | he/she/it has underestimated | they have underestimated |
| past perfect | | |
| 1 | I had underestimated | we had underestimated |
| 2 | you had underestimated | you had underestimated |
| 3 | he/she/it had underestimated | they had underestimated |
| future perfect | | |
| 1 | I will have underestimated | we will have underestimated |
| 2 | you will have underestimated | you will have underestimated |
| 3 | he/she/it will have underestimated | they will have underestimated |
| conditional perfect | | |
| 1 | I would have underestimated | we would have underestimated |
| 2 | you would have underestimated | you would have underestimated |
| 3 | he/she/it would have underestimated | they would have underestimated |
