Conversion Table

The following table provides details on how Pydantic converts data during validation in both strict and lax modes.

The "Strict" column contains checkmarks for type conversions that are allowed when validating in Strict Mode.

Field Type Input Strict Input Source Conditions
bool bool Python & JSON
bool float Python & JSON Allowed values: 0.0, 1.0.
bool int Python & JSON Allowed values: 0, 1.
bool str Python & JSON Allowed values: 'f', 'n', 'no', 'off', 'false', 'False', 't', 'y', 'on', 'yes', 'true', 'True'.
bool Decimal Python Allowed values: Decimal(0), Decimal(1).
bytes bytearray Python
bytes bytes Python
bytes str JSON
bytes str Python
callable - JSON Never valid.
callable Any Python callable() check must return True.
date bytes Python Format: YYYY-MM-DD (UTF-8).
date date Python
date datetime Python Must be exact date, eg. no H, M, S, f.
date float Python & JSON Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
date int Python & JSON Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
date str Python & JSON Format: YYYY-MM-DD.
date Decimal Python Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
datetime bytes Python Format: YYYY-MM-DDTHH:MM:SS.f. See speedate, (UTF-8).
datetime date Python
datetime datetime Python
datetime float Python & JSON Interpreted as seconds or ms from epoch, see speedate.
datetime int Python & JSON Interpreted as seconds or ms from epoch, see speedate.
datetime str Python & JSON Format: YYYY-MM-DDTHH:MM:SS.f. See speedate.
datetime Decimal Python Interpreted as seconds or ms from epoch, see speedate.
deque deque Python
deque frozenset Python
deque list Python
deque set Python
deque tuple Python
deque Array JSON
dict dict Python
dict Mapping Python Must implement the mapping interface and have an items() method.
dict Object JSON
float bool Python & JSON
float bytes Python Must match [0-9]+(\.[0-9]+)?.
float float Python & JSON bool is explicitly forbidden.
float int Python & JSON
float str Python & JSON Must match [0-9]+(\.[0-9]+)?.
float Decimal Python
frozenset deque Python
frozenset dict_keys Python
frozenset dict_values Python
frozenset frozenset Python
frozenset list Python
frozenset set Python
frozenset tuple Python
frozenset Array JSON
int bool Python & JSON
int bytes Python i64, Must be numeric only, e.g. [0-9]+.
int float Python & JSON i64, Must be exact int, e.g. val % 1 == 0, raises error for nan, inf.
int int Python & JSON Max abs value 2^64 as i64 is used internally; bool is explicitly forbidden.
int int Python & JSON i64. Limits numbers > (2 ^ 63) - 1 to (2 ^ 63) - 1.
int str Python & JSON i64, Must be numeric only, e.g. [0-9]+.
int Decimal Python i64, Must be exact int, e.g. val % 1 == 0.
list deque Python
list dict_keys Python
list dict_values Python
list frozenset Python
list list Python
list set Python
list tuple Python
list Array JSON
namedtuple dict Python
namedtuple list Python
namedtuple namedtuple Python
namedtuple tuple Python
namedtuple Array JSON
namedtuple NamedTuple Python
set deque Python
set dict_keys Python
set dict_values Python
set frozenset Python
set list Python
set set Python
set tuple Python
set Array JSON
str bytearray Python Assumes UTF-8, error on unicode decoding error.
str bytes Python Assumes UTF-8, error on unicode decoding error.
str str Python & JSON
time bytes Python Format: HH:MM:SS.FFFFFF. See speedate.
time float Python & JSON Interpreted as seconds, range 0 - 86399.9*.
time int Python & JSON Interpreted as seconds, range 0 - 86399.
time str Python & JSON Format: HH:MM:SS.FFFFFF. See speedate.
time time Python
time Decimal Python Interpreted as seconds, range 0 - 86399.9*.
timedelta bytes Python Format: ISO8601. See speedate, (UTF-8).
timedelta float Python & JSON Interpreted as seconds.
timedelta int Python & JSON Interpreted as seconds.
timedelta str Python & JSON Format: ISO8601. See speedate.
timedelta timedelta Python
timedelta Decimal Python Interpreted as seconds.
tuple deque Python
tuple dict_keys Python
tuple dict_values Python
tuple frozenset Python
tuple list Python
tuple set Python
tuple tuple Python
tuple Array JSON
Any Any Python & JSON
ByteSize float Python & JSON
ByteSize int Python & JSON
ByteSize str Python & JSON
ByteSize Decimal Python
Decimal float JSON
Decimal float Python & JSON
Decimal int JSON
Decimal int Python & JSON
Decimal str JSON
Decimal str Python & JSON Must match [0-9]+(\.[0-9]+)?.
Decimal Decimal Python
Enum Any JSON Input value must be convertible to enum values.
Enum Any Python Input value must be convertible to enum values.
Enum Enum Python
IPv4Address bytes Python
IPv4Address int Python integer representing the IP address, must be less than 2**32
IPv4Address str JSON
IPv4Address str Python & JSON
IPv4Address IPv4Address Python
IPv4Address IPv4Interface Python
IPv4Interface bytes Python
IPv4Interface int Python integer representing the IP address, must be less than 2**32
IPv4Interface str JSON
IPv4Interface str Python & JSON
IPv4Interface tuple Python
IPv4Interface IPv4Address Python
IPv4Interface IPv4Interface Python
IPv4Network bytes Python
IPv4Network int Python integer representing the IP network, must be less than 2**32
IPv4Network str JSON
IPv4Network str Python & JSON
IPv4Network IPv4Address Python
IPv4Network IPv4Interface Python
IPv4Network IPv4Network Python
IPv6Address bytes Python
IPv6Address int Python integer representing the IP address, must be less than 2**128
IPv6Address str JSON
IPv6Address str Python & JSON
IPv6Address IPv6Address Python
IPv6Address IPv6Interface Python
IPv6Interface bytes Python
IPv6Interface int Python integer representing the IP address, must be less than 2**128
IPv6Interface str JSON
IPv6Interface str Python & JSON
IPv6Interface tuple Python
IPv6Interface IPv6Address Python
IPv6Interface IPv6Interface Python
IPv6Network bytes Python
IPv6Network int Python integer representing the IP address, must be less than 2**128
IPv6Network str JSON
IPv6Network str Python & JSON
IPv6Network IPv6Address Python
IPv6Network IPv6Interface Python
IPv6Network IPv6Network Python
InstanceOf - JSON Never valid.
InstanceOf Any Python isinstance() check must return True.
IntEnum Any JSON Input value must be convertible to enum values.
IntEnum Any Python Input value must be convertible to enum values.
IntEnum IntEnum Python
Iterable deque Python
Iterable frozenset Python
Iterable list Python
Iterable set Python
Iterable tuple Python
Iterable Array JSON
NamedTuple dict Python
NamedTuple list Python
NamedTuple namedtuple Python
NamedTuple tuple Python
NamedTuple Array JSON
NamedTuple NamedTuple Python
None None Python & JSON
Path str JSON
Path str Python
Path Path Python
Pattern bytes Python Input must be a valid pattern.
Pattern str Python & JSON Input must be a valid pattern.
Sequence deque Python
Sequence list Python
Sequence tuple Python
Sequence Array JSON
Type Type Python
TypedDict dict Python
TypedDict Any Python
TypedDict Mapping Python Must implement the mapping interface and have an items() method.
TypedDict Object JSON
UUID str JSON
UUID str Python
UUID UUID Python
Field Type Input Strict Input Source Conditions
bool bool Python & JSON
bool float Python & JSON Allowed values: 0.0, 1.0.
bool int Python & JSON Allowed values: 0, 1.
bool str Python & JSON Allowed values: 'f', 'n', 'no', 'off', 'false', 'False', 't', 'y', 'on', 'yes', 'true', 'True'.
bytes str JSON
callable - JSON Never valid.
date float Python & JSON Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
date int Python & JSON Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
date str Python & JSON Format: YYYY-MM-DD.
datetime float Python & JSON Interpreted as seconds or ms from epoch, see speedate.
datetime int Python & JSON Interpreted as seconds or ms from epoch, see speedate.
datetime str Python & JSON Format: YYYY-MM-DDTHH:MM:SS.f. See speedate.
deque Array JSON
dict Object JSON
float bool Python & JSON
float float Python & JSON bool is explicitly forbidden.
float int Python & JSON
float str Python & JSON Must match [0-9]+(\.[0-9]+)?.
frozenset Array JSON
int bool Python & JSON
int float Python & JSON i64, Must be exact int, e.g. val % 1 == 0, raises error for nan, inf.
int int Python & JSON Max abs value 2^64 as i64 is used internally; bool is explicitly forbidden.
int int Python & JSON i64. Limits numbers > (2 ^ 63) - 1 to (2 ^ 63) - 1.
int str Python & JSON i64, Must be numeric only, e.g. [0-9]+.
list Array JSON
namedtuple Array JSON
set Array JSON
str str Python & JSON
time float Python & JSON Interpreted as seconds, range 0 - 86399.9*.
time int Python & JSON Interpreted as seconds, range 0 - 86399.
time str Python & JSON Format: HH:MM:SS.FFFFFF. See speedate.
timedelta float Python & JSON Interpreted as seconds.
timedelta int Python & JSON Interpreted as seconds.
timedelta str Python & JSON Format: ISO8601. See speedate.
tuple Array JSON
Any Any Python & JSON
ByteSize float Python & JSON
ByteSize int Python & JSON
ByteSize str Python & JSON
Decimal float JSON
Decimal float Python & JSON
Decimal int JSON
Decimal int Python & JSON
Decimal str JSON
Decimal str Python & JSON Must match [0-9]+(\.[0-9]+)?.
Enum Any JSON Input value must be convertible to enum values.
IPv4Address str JSON
IPv4Address str Python & JSON
IPv4Interface str JSON
IPv4Interface str Python & JSON
IPv4Network str JSON
IPv4Network str Python & JSON
IPv6Address str JSON
IPv6Address str Python & JSON
IPv6Interface str JSON
IPv6Interface str Python & JSON
IPv6Network str JSON
IPv6Network str Python & JSON
InstanceOf - JSON Never valid.
IntEnum Any JSON Input value must be convertible to enum values.
Iterable Array JSON
NamedTuple Array JSON
None None Python & JSON
Path str JSON
Pattern str Python & JSON Input must be a valid pattern.
Sequence Array JSON
TypedDict Object JSON
UUID str JSON
Field Type Input Strict Input Source Conditions
bool bool Python & JSON
bytes str JSON
deque Array JSON
dict Object JSON
float float Python & JSON bool is explicitly forbidden.
float int Python & JSON
frozenset Array JSON
int int Python & JSON Max abs value 2^64 as i64 is used internally; bool is explicitly forbidden.
list Array JSON
namedtuple Array JSON
set Array JSON
str str Python & JSON
tuple Array JSON
Any Any Python & JSON
ByteSize float Python & JSON
ByteSize int Python & JSON
ByteSize str Python & JSON
Decimal float JSON
Decimal int JSON
Decimal str JSON
Enum Any JSON Input value must be convertible to enum values.
IPv4Address str JSON
IPv4Interface str JSON
IPv4Network str JSON
IPv6Address str JSON
IPv6Interface str JSON
IPv6Network str JSON
IntEnum Any JSON Input value must be convertible to enum values.
Iterable Array JSON
NamedTuple Array JSON
None None Python & JSON
Path str JSON
Pattern str Python & JSON Input must be a valid pattern.
Sequence Array JSON
TypedDict Object JSON
UUID str JSON
Field Type Input Strict Input Source Conditions
bool bool Python & JSON
bool float Python & JSON Allowed values: 0.0, 1.0.
bool int Python & JSON Allowed values: 0, 1.
bool str Python & JSON Allowed values: 'f', 'n', 'no', 'off', 'false', 'False', 't', 'y', 'on', 'yes', 'true', 'True'.
bool Decimal Python Allowed values: Decimal(0), Decimal(1).
bytes bytearray Python
bytes bytes Python
bytes str Python
callable Any Python callable() check must return True.
date bytes Python Format: YYYY-MM-DD (UTF-8).
date date Python
date datetime Python Must be exact date, eg. no H, M, S, f.
date float Python & JSON Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
date int Python & JSON Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
date str Python & JSON Format: YYYY-MM-DD.
date Decimal Python Interpreted as seconds or ms from epoch. See speedate. Must be exact date.
datetime bytes Python Format: YYYY-MM-DDTHH:MM:SS.f. See speedate, (UTF-8).
datetime date Python
datetime datetime Python
datetime float Python & JSON Interpreted as seconds or ms from epoch, see speedate.
datetime int Python & JSON Interpreted as seconds or ms from epoch, see speedate.
datetime str Python & JSON Format: YYYY-MM-DDTHH:MM:SS.f. See speedate.
datetime Decimal Python Interpreted as seconds or ms from epoch, see speedate.
deque deque Python
deque frozenset Python
deque list Python
deque set Python
deque tuple Python
dict dict Python
dict Mapping Python Must implement the mapping interface and have an items() method.
float bool Python & JSON
float bytes Python Must match [0-9]+(\.[0-9]+)?.
float float Python & JSON bool is explicitly forbidden.
float int Python & JSON
float str Python & JSON Must match [0-9]+(\.[0-9]+)?.
float Decimal Python
frozenset deque Python
frozenset dict_keys Python
frozenset dict_values Python
frozenset frozenset Python
frozenset list Python
frozenset set Python
frozenset tuple Python
int bool Python & JSON
int bytes Python i64, Must be numeric only, e.g. [0-9]+.
int float Python & JSON i64, Must be exact int, e.g. val % 1 == 0, raises error for nan, inf.
int int Python & JSON Max abs value 2^64 as i64 is used internally; bool is explicitly forbidden.
int int Python & JSON i64. Limits numbers > (2 ^ 63) - 1 to (2 ^ 63) - 1.
int str Python & JSON i64, Must be numeric only, e.g. [0-9]+.
int Decimal Python i64, Must be exact int, e.g. val % 1 == 0.
list deque Python
list dict_keys Python
list dict_values Python
list frozenset Python
list list Python
list set Python
list tuple Python
namedtuple dict Python
namedtuple list Python
namedtuple namedtuple Python
namedtuple tuple Python
namedtuple NamedTuple Python
set deque Python
set dict_keys Python
set dict_values Python
set frozenset Python
set list Python
set set Python
set tuple Python
str bytearray Python Assumes UTF-8, error on unicode decoding error.
str bytes Python Assumes UTF-8, error on unicode decoding error.
str str Python & JSON
time bytes Python Format: HH:MM:SS.FFFFFF. See speedate.
time float Python & JSON Interpreted as seconds, range 0 - 86399.9*.
time int Python & JSON Interpreted as seconds, range 0 - 86399.
time str Python & JSON Format: HH:MM:SS.FFFFFF. See speedate.
time time Python
time Decimal Python Interpreted as seconds, range 0 - 86399.9*.
timedelta bytes Python Format: ISO8601. See speedate, (UTF-8).
timedelta float Python & JSON Interpreted as seconds.
timedelta int Python & JSON Interpreted as seconds.
timedelta str Python & JSON Format: ISO8601. See speedate.
timedelta timedelta Python
timedelta Decimal Python Interpreted as seconds.
tuple deque Python
tuple dict_keys Python
tuple dict_values Python
tuple frozenset Python
tuple list Python
tuple set Python
tuple tuple Python
Any Any Python & JSON
ByteSize float Python & JSON
ByteSize int Python & JSON
ByteSize str Python & JSON
ByteSize Decimal Python
Decimal float Python & JSON
Decimal int Python & JSON
Decimal str Python & JSON Must match [0-9]+(\.[0-9]+)?.
Decimal Decimal Python
Enum Any Python Input value must be convertible to enum values.
Enum Enum Python
IPv4Address bytes Python
IPv4Address int Python integer representing the IP address, must be less than 2**32
IPv4Address str Python & JSON
IPv4Address IPv4Address Python
IPv4Address IPv4Interface Python
IPv4Interface bytes Python
IPv4Interface int Python integer representing the IP address, must be less than 2**32
IPv4Interface str Python & JSON
IPv4Interface tuple Python
IPv4Interface IPv4Address Python
IPv4Interface IPv4Interface Python
IPv4Network bytes Python
IPv4Network int Python integer representing the IP network, must be less than 2**32
IPv4Network str Python & JSON
IPv4Network IPv4Address Python
IPv4Network IPv4Interface Python
IPv4Network IPv4Network Python
IPv6Address bytes Python
IPv6Address int Python integer representing the IP address, must be less than 2**128
IPv6Address str Python & JSON
IPv6Address IPv6Address Python
IPv6Address IPv6Interface Python
IPv6Interface bytes Python
IPv6Interface int Python integer representing the IP address, must be less than 2**128
IPv6Interface str Python & JSON
IPv6Interface tuple Python
IPv6Interface IPv6Address Python
IPv6Interface IPv6Interface Python
IPv6Network bytes Python
IPv6Network int Python integer representing the IP address, must be less than 2**128
IPv6Network str Python & JSON
IPv6Network IPv6Address Python
IPv6Network IPv6Interface Python
IPv6Network IPv6Network Python
InstanceOf Any Python isinstance() check must return True.
IntEnum Any Python Input value must be convertible to enum values.
IntEnum IntEnum Python
Iterable deque Python
Iterable frozenset Python
Iterable list Python
Iterable set Python
Iterable tuple Python
NamedTuple dict Python
NamedTuple list Python
NamedTuple namedtuple Python
NamedTuple tuple Python
NamedTuple NamedTuple Python
None None Python & JSON
Path str Python
Path Path Python
Pattern bytes Python Input must be a valid pattern.
Pattern str Python & JSON Input must be a valid pattern.
Sequence deque Python
Sequence list Python
Sequence tuple Python
Type Type Python
TypedDict dict Python
TypedDict Any Python
TypedDict Mapping Python Must implement the mapping interface and have an items() method.
UUID str Python
UUID UUID Python
Field Type Input Strict Input Source Conditions
bool bool Python & JSON
bytes bytes Python
callable Any Python callable() check must return True.
date date Python
datetime datetime Python
deque deque Python
dict dict Python
float float Python & JSON bool is explicitly forbidden.
float int Python & JSON
frozenset frozenset Python
int int Python & JSON Max abs value 2^64 as i64 is used internally; bool is explicitly forbidden.
list list Python
namedtuple dict Python
namedtuple list Python
namedtuple namedtuple Python
namedtuple tuple Python
namedtuple NamedTuple Python
set set Python
str str Python & JSON
time time Python
timedelta timedelta Python
tuple tuple Python
Any Any Python & JSON
ByteSize float Python & JSON
ByteSize int Python & JSON
ByteSize str Python & JSON
ByteSize Decimal Python
Decimal Decimal Python
Enum Enum Python
IPv4Address IPv4Address Python
IPv4Address IPv4Interface Python
IPv4Interface IPv4Interface Python
IPv4Network IPv4Network Python
IPv6Address IPv6Address Python
IPv6Address IPv6Interface Python
IPv6Interface IPv6Interface Python
IPv6Network IPv6Network Python
InstanceOf Any Python isinstance() check must return True.
IntEnum IntEnum Python
Iterable deque Python
Iterable frozenset Python
Iterable list Python
Iterable set Python
Iterable tuple Python
NamedTuple dict Python
NamedTuple list Python
NamedTuple namedtuple Python
NamedTuple tuple Python
NamedTuple NamedTuple Python
None None Python & JSON
Path Path Python
Pattern bytes Python Input must be a valid pattern.
Pattern str Python & JSON Input must be a valid pattern.
Sequence list Python
Type Type Python
TypedDict dict Python
TypedDict Any Python
UUID UUID Python