你应该用humanize。

>>> humanize.naturalsize(1000000)
'1.0 MB'
>>> humanize.naturalsize(1000000, binary=True)
'976.6 KiB'
>>> humanize.naturalsize(1000000, gnu=True)
'976.6K'

参考: https://pypi.org/project/humanize/

我喜欢senderle的十进制版本的固定精度，所以这里有一种与上面joctee的答案的混合(你知道你可以取非整数底数的对数吗?):

from math import log
def human_readable_bytes(x):
    # hybrid of https://stackoverflow.com/a/10171475/2595465
    #      with https://stackoverflow.com/a/5414105/2595465
    if x == 0: return '0'
    magnitude = int(log(abs(x),10.24))
    if magnitude > 16:
        format_str = '%iP'
        denominator_mag = 15
    else:
        float_fmt = '%2.1f' if magnitude % 3 == 1 else '%1.2f'
        illion = (magnitude + 1) // 3
        format_str = float_fmt + ['', 'K', 'M', 'G', 'T', 'P'][illion]
    return (format_str % (x * 1.0 / (1024 ** illion))).lstrip('0')

这将在几乎任何情况下做你需要做的事情，是可选参数自定义的，正如你所看到的，几乎是自文档化的:

from math import log
def pretty_size(n,pow=0,b=1024,u='B',pre=['']+[p+'i'for p in'KMGTPEZY']):
    pow,n=min(int(log(max(n*b**pow,1),b)),len(pre)-1),n*b**pow
    return "%%.%if %%s%%s"%abs(pow%(-pow-1))%(n/b**float(pow),pre[pow],u)

示例输出:

>>> pretty_size(42)
'42 B'

>>> pretty_size(2015)
'2.0 KiB'

>>> pretty_size(987654321)
'941.9 MiB'

>>> pretty_size(9876543210)
'9.2 GiB'

>>> pretty_size(0.5,pow=1)
'512 B'

>>> pretty_size(0)
'0 B'

高级定制:

>>> pretty_size(987654321,b=1000,u='bytes',pre=['','kilo','mega','giga'])
'987.7 megabytes'

>>> pretty_size(9876543210,b=1000,u='bytes',pre=['','kilo','mega','giga'])
'9.9 gigabytes'

此代码与Python 2和Python 3兼容。对读者来说，遵从PEP8是一个练习。记住，漂亮的是输出。

更新:

如果你需要数千个逗号，只需应用明显的扩展:

def prettier_size(n,pow=0,b=1024,u='B',pre=['']+[p+'i'for p in'KMGTPEZY']):
    r,f=min(int(log(max(n*b**pow,1),b)),len(pre)-1),'{:,.%if} %s%s'
    return (f%(abs(r%(-r-1)),pre[r],u)).format(n*b**pow/b**float(r))

例如:

>>> pretty_units(987654321098765432109876543210)
'816,968.5 YiB'

为了以人类可读的形式获取文件大小，我创建了这个函数:

import os

def get_size(path):
    size = os.path.getsize(path)
    if size < 1024:
        return f"{size} bytes"
    elif size < pow(1024,2):
        return f"{round(size/1024, 2)} KB"
    elif size < pow(1024,3):
        return f"{round(size/(pow(1024,2)), 2)} MB"
    elif size < pow(1024,4):
        return f"{round(size/(pow(1024,3)), 2)} GB"

>>> get_size("a.txt")
1.4KB

下面是一个使用while的选项:

def number_format(n):
   n2, n3 = n, 0
   while n2 >= 1e3:
      n2 /= 1e3
      n3 += 1
   return '%.3f' % n2 + ('', ' k', ' M', ' G')[n3]

s = number_format(9012345678)
print(s == '9.012 G')

https://docs.python.org/reference/compound_stmts.html#while

一个拥有你所寻找的所有功能的库似乎是人性化的。Humanize.naturalsize()似乎可以做您所寻找的所有事情。

示例代码(python 3.10)

import humanize

disk_sizes_list = [1, 100, 999, 1000,1024, 2000,2048, 3000, 9999, 10000, 2048000000, 9990000000, 9000000000000000000000]
for size in disk_sizes_list:
    natural_size = humanize.naturalsize(size)
    binary_size = humanize.naturalsize(size, binary=True)
    print(f" {natural_size} \t| {binary_size}\t|{size}")

输出

 1 Byte     | 1 Byte    |1
 100 Bytes  | 100 Bytes |100
 999 Bytes  | 999 Bytes |999
 1.0 kB     | 1000 Bytes    |1000
 1.0 kB     | 1.0 KiB   |1024
 2.0 kB     | 2.0 KiB   |2000
 2.0 kB     | 2.0 KiB   |2048
 3.0 kB     | 2.9 KiB   |3000
 10.0 kB    | 9.8 KiB   |9999
 10.0 kB    | 9.8 KiB   |10000
 2.0 GB     | 1.9 GiB   |2048000000
 10.0 GB    | 9.3 GiB   |9990000000
 9.0 ZB     | 7.6 ZiB   |9000000000000000000000