How to calculate the capacitance of a capacitor?

Question

Electronics

Task: put a capacitor of the nth capacity in the power circuit so that it can support the operation of the device for time t.
Given: Consumer current I=500mA;
Required voltage: 4V;
Required conder operation time t=1-2 s;
Help count.
PS if interested: this is a gps tracker that will certainly send an emergency text message to the user if it loses power.
Please do not offer batteries and accumulators. Need cheapness

Answer 1

3 * current * time / voltage = capacitance

Answer 2

This will be a few farads, and not at all cheaper than a battery / battery.
Formulas can be viewed for example here: tel-spb.ru/tau.html