Nope.
Fingers are only on the hand, except for figurative uses such as ladyfingers (a dessert).
If you talk about the fingers on someone's foot, or a person with 20 fingers, unfortunately you'll just generate unsettling mental images.
:)
As smci points out, to refer to the ensemble, people will often say "fingers and toes".
This is a so-called " Siamese twin " phrase: the two words love to be paired and the order can't be reversed.
We do also have a single word that covers both fingers and toes: digits .
It registers as a somewhat technical term, likely something your doctor would write in a report about an injury.
I think most people would understand it in other contexts anyway, though some speakers might not realize that it can apply to toes, probably because of the influence of "finger".
(Also, someone's "digits" is a way of referring to their phone number.)
A third alternative is "appendages", which everyone will understand, but which is usually too broad (see comments below) and simply sounds funny when used of regular human body parts.
ell.stackexchange.com/users/50807/Luke Sawczak
Toes are not fingers.
The general term for fingers and toes is digits .
We have twenty digits: ten fingers and ten toes.
In French, the toes are called 'doigts de pied' ('fingers of the foot'), also 'orteils'.
Doigt nom
masculin Chacune des parties libres et mobiles qui terminent la main de l'homme :
Compter sur ses doigts.
Toe Digit Doigt (Larousse)
ell.stackexchange.com/users/46805/Michael Harvey
No, the correct term to use in your case would be digits .
This means both fingers and toes.
ell.stackexchange.com/users/89698/Mike Brockington
Heh.
There is one particular case where you could do it, but it's pretty bizarre.
If a person loses his thumb, this will have major effects on the function of the hand as a whole.
Thumbs are important .
In such cases, the preferred treatment is to transplant the big toe of the appropriate foot to substitute for the missing thumb.
Big toes are not nearly as important to proper functioning of a foot.
With time, the pad of the transplanted toe will shrink, and with use and therapy the toe joint will become more flexible.
The result is not a perfect replacement, but it's much better than the alternative.
In this case, you could talk about having 10 fingers when one of them is (or at least started out as) a toe.
You could even have two, if you're unfortunate.
Other than that, the other answers are spot on:
English makes a clear distinction between fingers and toes.
ell.stackexchange.com/users/21298/WhatRoughBeast
Can I use fingers when referring to toes?
Would saying that a human has 20 fingers make sense, in English?
No.
I don't believe there is any context in which this would be correct - not even some of the unusual ones suggested by other people.
I agree that 20 digits is correct.
We could say, "The typical human has ten fingers and toes."
ell.stackexchange.com/users/21249/chasly - reinstate Monica
You could refer to toes as fingers as a metaphor if you were describing someone with uncommon dexterity in their toes.
The crowd was amazed when the escape artist kicked off his shoes andhis newly exposed fingers untied the knot.
If you mean the toes themselves, then describing them as fingers would be wrong, and confusing.
ell.stackexchange.com/users/54464/cmm
I have only used the word 'fingers' to refer to 'toes' when looking at some pre-Renaissance and Renaissance paintings where barefoot figures looked like they had fingers for toes.
ell.stackexchange.com/users/1313/Xenson
No "fingers and toes" is what we would say in everyday speech or writing (not "digits", which is more technical/precise).
(Yes, to be pedantic, "finger" is here referring to both fingers and thumbs
) "digits" is the more technical/precise term, but you'd almost never hear that spoken, except when discussing anatomy.
ell.stackexchange.com/users/5551/smci
Humans have 10 fingers and 10 toes.
It would not be correct to say that we have 20 fingers or 20 toes.
Fingers are only on our hands, and toes are only on our feet.
However, a general word "digits" can be used to say that we have 20 digits altogether.
ell.stackexchange.com/users/44527/magnetar
In my native language, there is no word for  toes . You just use the same word for both toes and fingers. In this context, I would say a human has 20 fingers.   Recently I've heard someone saying a human has 10 fingers (without saying it out loud but assuming that the other 10 are toes and not fingers).  Can I use  fingers  when referring to  toes ? Would saying that a human has 20 fingers make sense, in English?
Can I say "fingers" when referring to toes?
ell.stackexchange.com
<word-usage><word-meaning>
ell.stackexchange.com/questions/201499
ell.stackexchange.com/users/91666/aMJay
 Fingers are only on the hand, except for figurative uses such as ladyfingers (a dessert). However, we do also have a single word that covers both fingers and toes:  digits.  English makes a clear distinction between fingers and toes. Fingers and toes are not the same thing but digits is a word that can be used t encompass both. 
Fingers and toes are not the same thing. Digits is a word that would encompass both. 