Sensor Measurement Lists (SenML)

Created
2018-06-01
Last Updated
2026-02-02
Note
In SDF [RFC 9880], a URI unit name is distinguished from a 
registered unit name by the presence of a colon; any registered unit 
name that contains a colon can therefore not be directly used in SDF.
Available Formats

XML
HTML
TXT

Registries Included Below

SenML Units

Registration Procedure(s)
Expert Review
Expert(s)
Ari Keränen
Reference
[RFC 8428]
Note
Units marked with an asterisk are NOT RECOMMENDED to be 
produced by new implementations but are in active use and 
SHOULD be implemented by consumers that can use the 
corresponding SenML units that are closer to the unscaled SI
units.
Available Formats

CSV
Symbol Description Type Reference
m meter float [RFC 8428]
kg kilogram float [RFC 8428]
g gram* float [RFC 8428]
s second float [RFC 8428]
A ampere float [RFC 8428]
K kelvin float [RFC 8428]
cd candela float [RFC 8428]
mol mole float [RFC 8428]
Hz hertz float [RFC 8428]
rad radian float [RFC 8428]
sr steradian float [RFC 8428]
N newton float [RFC 8428]
Pa pascal float [RFC 8428]
J joule float [RFC 8428]
W watt float [RFC 8428]
C coulomb float [RFC 8428]
V volt float [RFC 8428]
F farad float [RFC 8428]
Ohm ohm float [RFC 8428]
S siemens float [RFC 8428]
Wb weber float [RFC 8428]
T tesla float [RFC 8428]
H henry float [RFC 8428]
Cel degrees Celsius float [RFC 8428]
lm lumen float [RFC 8428]
lx lux float [RFC 8428]
Bq becquerel float [RFC 8428]
Gy gray float [RFC 8428]
Sv sievert float [RFC 8428]
kat katal float [RFC 8428]
m2 square meter (area) float [RFC 8428]
m3 cubic meter (volume) float [RFC 8428]
l liter (volume)* float [RFC 8428]
m/s meter per second (velocity) float [RFC 8428]
m/s2 meter per square second (acceleration) float [RFC 8428]
m3/s cubic meter per second (flow rate) float [RFC 8428]
l/s liter per second (flow rate)* float [RFC 8428]
W/m2 watt per square meter (irradiance) float [RFC 8428]
cd/m2 candela per square meter (luminance) float [RFC 8428]
bit bit (information content) float [RFC 8428]
bit/s bit per second (data rate) float [RFC 8428]
lat degrees latitude[1] float [RFC 8428]
lon degrees longitude[1] float [RFC 8428]
pH pH value (acidity; logarithmic quantity) float [RFC 8428]
dB decibel (logarithmic quantity) float [RFC 8428]
dBW decibel relative to 1 W (power level) float [RFC 8428]
Bspl bel (sound pressure level; logarithmic quantity)* float [RFC 8428]
count 1 (counter value) float [RFC 8428]
/ 1 (ratio e.g., value of a switch; [2]) float [RFC 8428]
% 1 (ratio e.g., value of a switch; [2])* float [RFC 8428]
%RH Percentage (Relative Humidity) float [RFC 8428]
%EL Percentage (remaining battery energy level) float [RFC 8428]
EL seconds (remaining battery energy level) float [RFC 8428]
1/s 1 per second (event rate) float [RFC 8428]
1/min 1 per minute (event rate, "rpm")* float [RFC 8428]
beat/min 1 per minute (heart rate in beats per minute)* float [RFC 8428]
beats 1 (Cumulative number of heart beats)* float [RFC 8428]
S/m Siemens per meter (conductivity) float [RFC 8428]
B Byte (information content) float [RFC 8798]
VA volt-ampere (Apparent Power) float [RFC 8798]
VAs volt-ampere second (Apparent Energy) float [RFC 8798]
var volt-ampere reactive (Reactive Power) float [RFC 8798]
vars volt-ampere-reactive second (Reactive Energy) float [RFC 8798]
J/m joule per meter (Energy per distance) float [RFC 8798]
kg/m3 kilogram per cubic meter (mass density, mass concentration) float [RFC 8798]
deg degree (angle)* float [RFC 8798]
NTU Nephelometric Turbidity Unit float [ISO 7027-1:2016]

SenML Labels

Registration Procedure(s)
Expert Review
Expert(s)
Ari Keränen
Reference
[RFC 8428]
Available Formats

CSV
Name Label CBOR Label JSON Type XML Type EXI ID Reference Note
Base Name bn -2 String string a [RFC 8428]
Base Time bt -3 Number double a [RFC 8428]
Base Unit bu -4 String string a [RFC 8428]
Base Value bv -5 Number double a [RFC 8428]
Base Sum bs -6 Number double a [RFC 8428]
Base Version bver -1 Number int a [RFC 8428]
Name n 0 String string a [RFC 8428]
Unit u 1 String string a [RFC 8428]
Value v 2 Number double a [RFC 8428]
String Value vs 3 String string a [RFC 8428]
Boolean Value vb 4 Boolean boolean a [RFC 8428]
Data Value vd 8 String (*) string (*) a [RFC 8428] (*) Data Value is a base64-encoded string with the URL-safe alphabet as defined in Section 5 of [RFC 4648], with padding omitted. (In CBOR, the octets in the Data Value are encoded using a definite-length byte string, major type 2.)
Sum s 5 Number double a [RFC 8428]
Time t 6 Number double a [RFC 8428]
Update Time ut 7 Number double a [RFC 8428]
LwM2M Object Link vlo String string [OMA-TS-LightweightM2M_Core-V1_1_1-20190617-A] Section 7.4.5 of the OMA LwM2M 1.1 Core Technical Specification
Base Content-Format bct String string [RFC 9193]
Content-Format ct String string [RFC 9193]

Secondary Units

Registration Procedure(s)
Expert Review
Expert(s)
Ari Keränen
Reference
[RFC 8798]
Available Formats

CSV
Secondary Unit Description SenML Unit Scale Offset Reference
ms millisecond s 1/1000 0 [RFC 8798]
min minute s 60 0 [RFC 8798]
h hour s 3600 0 [RFC 8798]
MHz megahertz Hz 1000000 0 [RFC 8798]
kW kilowatt W 1000 0 [RFC 8798]
kVA kilovolt-ampere VA 1000 0 [RFC 8798]
kvar kilovar var 1000 0 [RFC 8798]
Ah ampere-hour C 3600 0 [RFC 8798]
Wh watt-hour J 3600 0 [RFC 8798]
kWh kilowatt-hour J 3600000 0 [RFC 8798]
varh var-hour vars 3600 0 [RFC 8798]
kvarh kilovar-hour vars 3600000 0 [RFC 8798]
kVAh kilovolt-ampere-hour VAs 3600000 0 [RFC 8798]
Wh/km watt-hour per kilometer J/m 3.6 0 [RFC 8798]
KiB kibibyte B 1024 0 [RFC 8798]
GB gigabyte B 1e9 0 [RFC 8798]
Mbit/s megabit per second bit/s 1000000 0 [RFC 8798]
B/s byte per second bit/s 8 0 [RFC 8798]
MB/s megabyte per second bit/s 8000000 0 [RFC 8798]
mV millivolt V 1/1000 0 [RFC 8798]
mA milliampere A 1/1000 0 [RFC 8798]
dBm decibel (milliwatt) dBW 1 -30 [RFC 8798]
ug/m3 microgram per cubic meter kg/m3 1e-9 0 [RFC 8798]
mm/h millimeter per hour m/s 1/3600000 0 [RFC 8798]
m/h meter per hour m/s 1/3600 0 [RFC 8798]
ppm parts per million / 1e-6 0 [RFC 8798]
/100 percent[3] / 1/100 0 [RFC 8798]
/1000 permille / 1/1000 0 [RFC 8798]
hPa hectopascal Pa 100 0 [RFC 8798]
mm millimeter m 1/1000 0 [RFC 8798]
cm centimeter m 1/100 0 [RFC 8798]
km kilometer m 1000 0 [RFC 8798]
km/h kilometer per hour m/s 1/3.6 0 [RFC 8798]
ppb parts per billion / 1e-9 0 [CoRE-1]
ppt parts per trillion / 1e-12 0 [CoRE-1]
VAh volt-ampere-hour VAs 3600 0 [CoRE-1]
mg/l milligram per liter kg/m3 1/1000 0 [CoRE-1]
ug/l microgram per liter kg/m3 1e-6 0 [CoRE-1]
g/l gram per liter kg/m3 1 0 [CoRE-1]

SenML Features

Registration Procedure(s)
Specification Required
Expert(s)
Ari Keränen (primary), Carsten Bormann (secondary)
Reference
[RFC 9100]
Available Formats

CSV
Feature Code Feature Name Reference
0 Reserved0 [RFC 9100]
1 Reserved1 [RFC 9100]
2 Reserved2 [RFC 9100]
3 Reserved3 [RFC 9100]
4 Secondary Units [RFC 9100][RFC 8798]
5-52 Unassigned

Footnotes

[1] 
Assumed to be in World Geodetic System 1984 (WGS84),
unless another reference frame is known for the sensor.
[2] 
A value of 0.0 indicates the switch is off, 1.0 indicates
on, and 0.5 indicates half on. The preferred name of this unit is
"/". For historical reasons, the name "%" is also provided for
the same unit, but note that while that name strongly suggests a
percentage (0..100), it is NOT a percentage but the absolute
ratio!
[3] 
This registration does not use the obvious name "%" because 
this name has been taken in [RFC 8428] already, where it is a 
NOT RECOMMENDED synonym for "/" (unity) for legacy reasons. 
Note that the presence of both "%" and "/100" with different 
meanings is likely to create confusion, so 
[RFC 8798] adds some weight 
to the recommendation against using the counterintuitive unit 
name "%".