Developer Utilities
Small developer utilities that save a trip to a random website. Encode and decode Base64, explain a regex, build UTM links, generate QR codes and vCards, and more — the everyday helpers. Free in your browser, and available by API when you need them in a script.
Developer Utilities
Subtract two HMS durations
hours, minutes and seconds calculator
POST /date/hms-subtract$0.002Developer Utilities
Hours minutes seconds to seconds
clock duration converter
POST /date/hms-to-seconds$0.002Developer Utilities
Total duration of time intervals
merge overlaps in UTC
POST /date/intervals-total-duration$0.002Developer Utilities
Add two ISO 8601 durations
combine and normalize PnYnMnDTnHnMnS
POST /date/iso-duration-add$0.002Developer Utilities
Overlapping time of two intervals calculator
POST /date/overlap-duration$0.002Developer Utilities
Stopwatch split times
cumulative splits to lap durations
POST /date/stopwatch-split-times$0.002Developer Utilities
Clock time to decimal minutes
minutes past midnight calculator
POST /date/time-to-decimal-minutes$0.002Developer Utilities
Working hours between two datetimes
UTC business time calculator
POST /date/working-hours-between$0.002Developer Utilities
Age in total weeks
whole weeks lived from birth date to reference date
POST /date/age-in-weeks$0.002Developer Utilities
Weekday of a birthday in any year
POST /date/birthday-weekday$0.002Developer Utilities
Hours difference between UTC offsets
signed fixed-offset calculator
POST /date/offset-difference-hours$0.002Developer Utilities
Pregnancy week from last period
gestational age in weeks + days
POST /date/pregnancy-week-from-lmp$0.002Developer Utilities
Retirement date from birthdate
calculate your eligibility date
POST /date/retirement-date$0.002Developer Utilities
Timesheet hours total
calculate work hours minus breaks
POST /date/timesheet-total$0.002Developer Utilities
Convert time between UTC offsets
fixed offset wall clock, free
POST /date/convert-between-offsets$0.002Developer Utilities
Day fraction to clock time
hours, minutes and seconds converter
POST /date/day-fraction-to-time$0.002Developer Utilities
Length of daylight calculator by date and latitude
POST /date/day-length-approx$0.002Developer Utilities
GMT offset label formatter
turn minutes into friendly text
POST /date/gmt-offset-label$0.002Developer Utilities
JavaScript timestamp to ISO 8601 converter
POST /date/js-timestamp-to-iso$0.002Developer Utilities
Swatch Internet Time
ISO datetime to .beats (Biel Mean Time)
POST /date/swatch-internet-time$0.002Developer Utilities
Unix seconds to ISO 8601
epoch timestamp to UTC datetime
POST /date/unix-seconds-to-iso$0.002Developer Utilities
Approximate equation of time
sundial to clock offset in minutes, free
POST /date/equation-of-time-approx$0.002Developer Utilities
Moon age in days calculator for any date
POST /date/moon-age-days$0.002Developer Utilities
Power from current and resistance
P=I²R calculator, free
POST /elec/power-i2r$0.002Developer Utilities
Resistance from power and voltage calculator
R = V² / P
POST /elec/resistance-from-power-voltage$0.002Developer Utilities
Voltage drop percentage calculator
check circuit regulation
POST /elec/voltage-drop-percent$0.002Developer Utilities
Voltage from power and current calculator
watts and amps to volts
POST /elec/voltage-from-power-current$0.002Developer Utilities
Charge from current and time calculator
Q=I·t coulombs free
POST /elec/charge-current-time-q$0.002Developer Utilities
Kirchhoff voltage law calculator
single-loop KVL unknown voltage
POST /elec/kirchhoff-voltage-law$0.002Developer Utilities
Norton equivalent calculator
current source and parallel resistance
POST /elec/norton-equivalent$0.002Developer Utilities
Resistor power dissipation calculator
safe wattage with margin
POST /elec/resistor-power-dissipation$0.002Developer Utilities
EIA-96 SMD resistor code calculator
decode 2-digit + letter codes
POST /elec/resistor-smd-eia96$0.002Developer Utilities
Two resistor parallel calculator
product over sum
POST /elec/two-resistors-parallel$0.002Developer Utilities
Voltage divider resistor calculator
find R2 from Vin, Vout and R1
POST /elec/voltage-divider-resistor$0.002Developer Utilities
Capacitance to capacitor code calculator
convert values to 3 digits
POST /elec/capacitor-code-encode$0.002Developer Utilities
NTC thermistor beta resistance calculator
POST /elec/ntc-thermistor-resistance$0.002Developer Utilities
Pull-up resistor current calculator
logic-low sink current
POST /elec/pull-up-resistor$0.002Developer Utilities
Five-band resistor color code calculator
ohms and tolerance
POST /elec/resistor-color-5band$0.002Developer Utilities
Resistor tolerance range calculator
min and max ohms from %
POST /elec/resistor-tolerance-range$0.002Developer Utilities
Two capacitor series calculator
product-over-sum Ceq, free
POST /elec/two-capacitors-series$0.002Developer Utilities
Capacitive voltage divider
Vout from two series capacitors, free
POST /elec/capacitive-divider$0.002Developer Utilities
Capacitor ESR power loss calculator
ripple-current heating
POST /elec/capacitor-esr-loss$0.002Developer Utilities
Capacitor dielectric field strength calculator
breakdown safety margin
POST /elec/dielectric-field-strength$0.002Developer Utilities
RC charging voltage at time calculator
V(t)=Vs(1−e^(−t/RC)), free
POST /elec/rc-charge-voltage$0.002Developer Utilities
RC snubber design calculator
resistor and capacitor for relay or MOSFET
POST /elec/rc-snubber$0.002Developer Utilities
Series capacitor voltage sharing calculator
check individual ratings
POST /elec/series-cap-voltage-share$0.002Developer Utilities
AC real power calculator
RMS voltage, RMS current and power factor
POST /elec/ac-real-power$0.002Developer Utilities
Air core solenoid inductance calculator
L = μ₀N²A/l
POST /elec/air-solenoid-inductance$0.002Developer Utilities
Coupling coefficient calculator
mutual and self inductance
POST /elec/coupling-coefficient$0.002Developer Utilities
Series RLC impedance calculator
magnitude and phase
POST /elec/impedance-rlc-series$0.002Developer Utilities
Inductance from reactance calculator
L = XL/(2πf) in henries, free
POST /elec/inductance-from-reactance$0.002Developer Utilities
Inductor current ripple calculator
ΔI = V·D/(L·f) peak-to-peak
POST /elec/inductor-current-ripple$0.002Developer Utilities
RF choke impedance calculator
check signal blocking
POST /elec/rf-choke-impedance$0.002Developer Utilities
Sine average voltage calculator
Vavg = (2/π)·Vpeak, free
POST /elec/vavg-sine$0.002Developer Utilities
VRMS from peak voltage calculator
Vpeak ÷ √2 sine wave, free
POST /elec/vrms-from-vpeak$0.002Developer Utilities
Series RL impedance calculator
|Z| and phase from R, L, f
POST /elec/impedance-rl-series$0.002Developer Utilities
Line to phase voltage calculator
V_LL ↔ V_LN with √3 (wye)
POST /elec/line-phase-voltage$0.002Developer Utilities
Phase shift to time delay calculator
POST /elec/phase-shift-time$0.002Developer Utilities
RLC resonance Q factor calculator
series and parallel circuits
POST /elec/resonance-q-factor$0.002Developer Utilities
Shockley diode equation calculator
calculate diode current
POST /elec/shockley-diode$0.002