つもり vs Simple Future


Several resources I've looked over define つもり as (often) being used to say "I
intend to ~", such as this example sentence from Genki I:

> 週末にたけしさんとテニスをする **つもり** です。 "I **intend to** play tennis with Takeshi this
> weekend"

To say in English that you intend to do something feels both more formal in
register and somewhat weaker than using the simple future "I will ~". Asking
about someone's plans for the night/vacation/project/etc is something that
comes up all the time, and I absolutely do not hear "I intend to do ~" under
most circumstances. That said, Genki introduces this construction quite early,
which makes me believe it must be more common in Japanese.

In what situations is it appropriate to say するつもり where it would not be
appropriate to say します? Is this a common construction for casual conversation,
or is it reserved for more polite and formal situations?




週末にたけしさんとテニスをします is an affirmation that you are going to play tennis on the
weekend. It is definite. Note that there is no such thing as a future tense or
an auxiliary verb that would correspond to English “will” in Japanese. It’s
just that the present (or non-past) affirmative form of a verb is used with an
expression that can be interpreted as referring to a future time. The same
sentence could be understood as describing what you do every weekend.

週末にたけしさんとテニスをするつもりです is more like saying you are planning on playing tennis
with Takeshi on the weekend. It is possible that you haven’t even talked to
Takeshi about it. It is only your intention and you know it might not happen
as you plan. Depending on the context, you could sound like you are
deliberately avoiding commitment.

週末にたけしさんとテニスをする予定です sounds more definite. It is likely that playing tennis
with Takeshi is already scheduled for the weekend.

The three sentences above are all neutral in register.

