Degrees

°

minutes

seconds

Decimal degrees

°

Radians

rad

π.rad

Metric

m²

mm²

cm²

km²

ha

US

in²

ft²

mi²

Metric

mg/L

g/cm³

g/L

kg/m³

mg/mL

US

lb/in³

lb/ft³

lb/gal

Metric

J

Wh

kWh

cal

kcal

N.m

kgf.m

US

BTU (iso)

hp.h

lb/in

Eq. ton of Coal

Eq. ton of Oil

Metric

kg/s

kg/min

kg/h

kg/day

US

lb/s

lb/min

lb/h

lb/day

Metric

m³/s

m³/min

m³/h

m³/day

L/s

L/min

L/h

US

gal/s (gps)

gal/min (gpm)

gal/h (gph)

gal/day (gpd)

Mgal/day (mgd)

ft³/min (cfm)

ft³/s (cfs)

Metric

L/m².h (LMH)

m³/m².day (m/day)

m³/m².h (m/h)

US

gal/ft².day (gfd)

gal/ft².h (gfh)

gal/ft².min (gfm)

Metric

N

kN

kgf

dyn

US

lbf

pdl

mg/L CaCO3

meq/L

mmol/L

°dH

°e

°fH

gpg

Metric

m

cm

mm

µm

nm

km

US

in

mil

ft

yd

mi

Metric

kg

g

mg

µg

metric ton

US

lb

oz

ton

Metric

W (J/s)

kW

cal/s

kcal/h

kgf.m/s

US

hp

bhp

BTU/s

Metric

bar

Pa

kPa

kg/cm² (kgf)

atm

mH2O

mmHg

US

psi

ftH2O

inHg

Metric

m/s

m/min

m/h (m³/m².h)

m/day (m³/m².day)

km/h

cm/h

cm/min

cm/s

US

in/h

in/min

in/s

ft/h (ft³/ft².h)

ft/min

ft/s

mi/h (mph)

mi/min (mpm)

°C

°F

Kelvin

Composite

days

hours

minutes

seconds

Decimal

days

hours

minutes

Metric

m³

L

mL

µL

pL

US

gal

in³

ft³

fl oz

	Diameter
	mm	in
	Height
	mm	in
	Volume
	L	ft³

	Diameter
	mm	in
	Height
	mm	in
	Volume
	L	ft³

	Sides length
	mm	in
	mm	in
	mm	in
	Volume
	L	ft³

Diameter
mm	in
Radius
mm	in
Perimeter
mm	in
Area
mm²	in²
m²	ft²

	Diameter
	mm	in
	Water height
	mm	in
	Length
	mm	in
	Volume
	L	ft³

	Calculation modes
	A1, A2, A3
	S2, S3, A1
	S3, A1, A2
	Side dimensions
S1	mm	in
S2	mm	in
S3	mm	in
	Angles*
A1	°	rad
A2	°	rad
A3	°	rad
	Perimeter
	mm	in
	Area
	mm²	in²
	m²	ft²

*Angles are named according to the opposite side name (example: A1 refers to the side S1).

Nominal pipe size / DN

Wall thickness designation

Equivalent thickness designations*

None

External diameter
mm	in
Internal diameter
mm	in
Internal area
mm²	in²
Wall thickness
mm	in

*Other designations with the same diameters and wall thickness.

Nominal Pipe Size dimensions from the ASME Standards B36.10M, ASME B36.19M and ISO 6708. Valid for Stainless Steel, Ductile Iron, PVC and CPVC pipes.

	Catchment area
	m²	ft²
	km²	mi²
	Precipitation
	mm	in
	Volume
	m³	ft³

Standard US Number

Standard Tyler Mesh

Opening
mm	in

Designations and sizes according to the ASTM-E11 (2015).

	Flow
	m³/h	gpm
	Diameter
	m	ft
	Rate
	m³/m².h	ft³/ft².h

	Flow
	m³/h	gpm
	Sides length
	m	ft
	m	ft
	Rate
	m³/m².h	ft³/ft².h

	Flow
	m³/h	gpm
	Reactor or clarifier volume
	m³	ft³
	Hydraulic retention time - HRT
	min	h

	Plant flow
	m³/h	gpm
	Waste sludge flow
	m³/h	gpm
	Solids concentration in the reactor¹
	mg/L	lb/gal
	Solids returning from the clarifier²
	mg/L	lb/gal
	Solids in the clarified/product water
	mg/L	lb/gal
	Reactor volume
	m³	ft³
	Solids retention time³ (SRT)
	h	days

¹ For activated sludges this can be the MLVSS (Mixed liquor volatile suspended solids) concentration in the aeration tank.

² Solids in the recirculation return to the reactor. For activated sludges this is the concentration in the return activated sludge (RAS) or the concentration in the waste sludge.

³ Also known as Mean Cell Residence Time (MCRT).

	Clarifier influent flow
	m³/h	gpm
	Solids influent concentration¹
	mg/L	lb/gal
	Clarifier cross-sectional area
	m²	ft²
	Solids loading rate
	kg/(m².h)	lb/(ft².h)

¹ For activated sludges this can be the MLVSS (Mixed liquor volatile suspended solids) concentration from the aeration tank. For water treatment clarifiers this is usually the TSS.

	Influent flow
	m³/h	gpm
	Solids influent concentration¹
	mg/L	lb/gal
	Clarifier/reactor volume
	m³	ft³
	Volumetric solids loading rate
	kg/(m³.day)	lb/(ft³.day)

¹ For activated sludges this can be the MLVSS (Mixed liquor volatile suspended solids) load in the clarifier or the BOD load in the aeration tank. For anaerobic reactors this is usually the COD load.

	Plant flow
	m³/h	gpm
	Recirculation sludge flow
	m³/h	gpm
	Return activated sludge recycle ratio¹
	%
	Solids concentration in the reactor²
	mg/L	lb/gal
	Solids returning from the clarifier³
	mg/L	lb/gal

¹ This ratio can be calculated either from the flows or from the solid concentrations.

² For activated sludges this can be the MLVSS (Mixed liquor volatile suspended solids) concentration in the aeration tank.

³ Solids in the recycle activated sludge (RAS) stream.

	Particle diameter
	mm	in
	Particle density
	kg/m³	lb/ft³
	Fluid density
	kg/m³	lb/ft³
	Kinematic viscosity
	m²/s	cSt
	Sedimentation rate*
	m/h	ft/h
	Reynolds

*Equation from Stokes law valid for round particles and laminar movement (Re lower than 1).

	Solids mass
	kg	lb
	Solids density*
	kg/m³	lb/ft³
	Solids percentage
	%w/w	mg/L (ppm)
	Sludge volume
	m³	gal

*Typical biological sludge has a solids density of 1550kg/m³, mineral sludge has a density of approx. 2600kg/m³.

	Influent flow
	m³/h	gpm
	Influent suspended solids¹
	mg/L	lb/gal
	Suspended solids in the reactor²
	mg/L	lb/gal
	Reactor volume³
	m³	ft³
	Sludge age
	h	days

¹ This can be either the VSS (volatile suspended solids) or the TSS (total suspended solids).

² This can be either the MLVSS (mixed liquor volatile suspended solids) or the MLSS (mixed liquor suspended solids). If using MLVSS, the inlet concentration must be VSS.

³ For activated sludges, the reactor is the aeration tank.

	Settled volume in 30min
	mL/L
	Total suspended solids
	mg/L	lb/gal
	Sludge volume index (SVI)
	mL/g

¹ This is also referred as the MLSS (mixed liquor suspended solids).

	Influent flow
	m³/h	gpm
	Influent BOD concentration
	mg/L	lb/gal
	Mixed liquor suspended solids¹
	mg/L	lb/gal
	Reactor volume
	m³	ft³
	Food-to-microorganisms ratio (F/M)

¹ This can be either the MLVSS (mixed liquor volatile suspended solids) or the MLSS (mixed liquor suspended solids).

	Flow
	m³/h	gpm
	Pipe roughness
	mm	in
	Kinematic viscosity
	m²/s
	Length
	m	ft
	Internal diameter
	mm	in
	Head loss
	m	ft
	Speed
	m/s	ft/s

	Section geometry

	Bottom width
	mm	in
	Side slope base width¹
	mm	in
	Internal diameter
	mm	in
	Water depth
	mm	in
	Slope of the channel²
	m/m or in/in	%
	Manning coefficient³
	Kinematic viscosity
	m²/s	cSt
	Flow
	m³/h	gpm
	Average velocity
	m/s	ft/s
	Reynolds
	Froude
	Kinetic energy
	m	ft
	Specific energy
	m	ft
	Hydraulic radius
	mm	in
	Wetted perimeter
	mm	in

¹ Base of the right-angle triangle with the water depth as height and the inclined side slope as hypotenuse. The model considers both side slopes as identical.

² Inclination of the channel or the altitude loss per horizontal length.

³ Typical values from literature: 0.013 for concrete or cast iron, 0.03 for gravel and 0.01 for smooth plastic.

	Pressure reading taps¹

	Pipe internal diameter
	mm	in
	Orifice internal diameter
	mm	in
	Fluid density
	kg/m³	lb/ft³
	Dynamic viscosity (µ)
	Pa.s	cP
	Flow
	m³/h	gpm
	Discharge coefficient
	Pressure drop between taps
	m	ft
	Overall headloss for the orifice plate
	m	ft

Calculations from the ISO 5167 (2003) and from the ASME MFC-14M (2001) valid for incompressible fluids, sharp edged orifice plates; orifice diameter >=12.5mm, 1m >; pipe diameter > 25mm, 0.75 >; orifice diameter/pipe diameter > 0.1

¹ Tap type and distances from the orifice plate, upstream and downstream. D stands for the pipe internal diameter.

	Standard throat width¹

	Primary measurement head² (Ha)
	mm	in
	Secondary measurement head³ (Hb)
	mm	in
	Flow
	m³/h	gpm
	Submergence ratio

¹ Standard sizes and discharge coefficients according to the ASTM D1941 (2013).

² Head measurement in the convergence section.

³ Head measurement in the throat section. Used only for submerged flow measurements, leave blank for free flow.

Free flow calculations according to the ASTM D1941 (2003). Submerged flow calculations according to the ISO 9826 (1992).

	Measurement head¹ (h)
	mm	in
	Approach channel width (B)
	mm	in
	Throat width (b)
	mm	in
	Throat length (L)
	mm	in
	Bump height² (p)
	mm	in
	Flow
	m³/h	gpm

Discharge coefficients and variable names according to the ISO 4359 (1983). Devices also known as Venturi flumes.

¹ According to the standard, the head is measured in the approach channel.

² Leave blank if the flume has a flat bottom (typical).

	Flow
	m³/h	gpm
	Fluid density
	kg/m³	lb/ft³
	Head
	m	ft
	Mechanic eff.
	%
	Electric eff.
	%
	Power
	kW	hp

	Flow
	Nm³/h	ft³/min
	Air density at NTP
	kg/m³	lb/ft³
	Intake pressure*
	bar	psi
	Output pressure*
	bar	psi
	Temperature
	°C	°F
	Mechanic eff.
	%
	Electric eff.
	%
	Power
	kW	hp

*Absolute pressures. Use the default value (1.013 bar) for intakes at the atmosphere pressure.

Calculations from Metcalf and Eddy, Wastewater Engineering, 2003

	Reactor volume
	m³	ft³
	Dynamic viscosity (µ)
	Pa.s	cP
	Power
	kW	hp
	Velocity gradient
	1/s

	Hydraulic diameter
	mm	in
	Flow
	m³/h	gpm
	Average speed
	m/s	ft/s
	Fluid density
	kg/m³	lb/ft³
	Dynamic viscosity (µ)
	Pa.s	cP
	Reynolds

Element

Atomic number
Atomic weight
Group
Electron configuration
None
Oxidation states
None
Melting point
°C	°F
Boiling point
°C	°F
Density
kg/m³	lb/ft³
Ionization energy
eV

Cations	mg/L	CaCO3	meq/L
Aluminum Al3+
Barium Ba2+
Calcium Ca2+
Copper Cu2+
Hydrogen H+
Ferrous ion Fe2+
Ferric ion Fe3+
Magnesium Mg2+
Manganese Mn2+
Potassium K+
Sodium Na+
Strontium Sr2+
Anions	mg/L	CaCO3	meq/L
Chloride Cl-
Fluoride F-
Iodine I-
Hydroxide OH-
Nitrate NO3-
Phosphate (dibasic) PO43-
Phosphate (tribasic) HPO42-
Phosphate (mono) H2PO4-
Sulfate SO42-
Bisulfate HSO4-
Sulfite SO32-
Sulfide S2-
pH
Carbonates	mg/L	CaCO3	meq/L
Carbon dioxide CO2
Bicarbonate HCO3-
Carbonate CO32-
Alkalinity-P
Alkalinity-M
Ammonia	mg/L	CaCO3	meq/L
Total Ammonia
Ammonium NH4+
Ammonia NH3
Neutrals	mg/L	CaCO3	meq/L
Silica* SiO2

Balance
Sum cations	meq/L
Sum anions	meq/L
Sum anions+silica+CO2	meq/L
Conductivity @ 25°C (if balanced)	µS/cm
Total Dissolved Solids (TDS)	mg/L

*For ion exchange purposes SiO₂ is considered weakly ionized as H₂SiO₃(silicic acid). SiO₂ has MW=60 and is removed as monovalent SiO₂^-.

Chemical Oxygen Demand (COD)

mg/L O2

Organic Matter as Permanganate

mg/L KMnO4

Biological Oxygen Demand (BOD)

mg/L O2

Total Organic Carbon (TOC)

mg/L C

Rough organic matter conversions based on the empiric factors from DOW Water and Process Solutions Answer Center for natural waters.

	Temperature
	°C	°F
	Calcium
	mg/L CaCO3	mg/L Ca
	Alkalinity
	mg/L CaCO3	mg/L HCO3
	Total Dissolved Solids
	mg/L
	pH
	LSI

Calculations from Edstrom Industries, 1998, Scale Forming Tendency of Water MI-4170.

	Temperature
	°C	°F
	Pressure
	bar	psi
	Active membrane diameter¹
	mm	in
	Membrane area
	m²	ft²
	Average flow during cake formation²
	L/h	gal/h
	Inverse of the average flow during cake formation² (Δt/ΔV)
	s/L	s/gal
	Filtrate volume during cake formation² (ΔV)
	L	gal
	MFI
	s/L²

Standard test conditions according to the ASTM D8002 (2015) for the MFI 0.45. The MFI will be normalized in case of different temperatures, areas or pressures from the standard test conditions.

¹ 47mm diameter membrane with 0.45µm mean pore size operating at 200±2KPa (2±0.02 bar). Active membrane diameter depends on the filter holder used.

² The cake formation is the linear segment of the (t/V) vs (V) graphic where t is the time in seconds and V is the filtrate volume in liters.

	Time for the first 500mL
	s	min
	Total elapsed time (T)*
	s	min
	Time for the last 500mL
	s	min
	SDIT
	Maximum SDI for T

*Total time of 15 minutes is the default for RO/NF membranes warranty terms.

	Water flow
	m³/h	gpm
	Chemical dosage*
	mg/L (ppm)	lb/ft³
	Stock concentration
	%w/w	mg/L (ppm)
	Stock density
	kg/m³ (g/L)	lb/ft³
	Chemical flow - mass
	kg/h	lb/h
	kg/day	lb/day
	Chemical flow - volume
	L/h	gph
	L/day	gpd

*Chemical dosage as if the product is 100% concentrated.

Chemical solution

Concentration
%w/w	mg/L (ppm)
Temperature
°C	°F
Density
kg/m³ (g/L)	lb/ft³

Properties interpolated from the tables provided by the chemical suppliers and from the Perry's Chemical Engineers Handbook.

Temperature
°C	°F
Density
kg/m³	lb/ft³
Dynamic Viscosity (µ)
Pa.s	cP
Kinematic Viscosity (v)
m²/s	cSt

Properties at the atmospheric pressure (100 KPa) in the liquid form. Equations from R.C. Weast, 1983, CRC Handbook of Chemistry and Physics, 64th edition and from the David R. Maidment, 2003 Handbook of Hydrology, McGraw-Hill.

Gas

Temperature
°C	°F
Density
kg/m³	lb/ft³
Molecular weight

Properties at the atmospheric pressure (100 KPa). Equations from MWH, 2005, Water Treatment Principles and Design 2nd edition.

Temperature
°C	°F
Barometric pressure
atm	mmHg
Salinity
%w/w	mg/L (ppm)
Solubility
mg/L

Equations from Benson and Krause,1980 and 1984.

Stream 1
Flow1
	%
Concentration2
Stream 2
Flow1
	%
Concentration2
Stream 3
Flow1
	%
Concentration2
Result mixture
Total flow
Concentration

¹ Allows any unit of flow or volume (L/h, m³/h, gpm, m³, L, gal, etc...).

² Allows any unit of concentration (mg/L, ppm, ppb, %, etc...) or temperatures.

	Flow
	m³/h	gpm
	Inlet solids
	mg/L
	Outlet solids
	mg/L
	Media capacity*
	mg/L
	Media volume
	L	ft³
	Run length
	hours	days
	Run volume
	m³	gal
	Contact time
	BV/h	min

*The media capacity is expressed as mg of solute per Liter of filter media. For ion exchange, the mg/L concentrations can be replaced by meq/L values.

	Flow
	m³/h	gpm
	Media volume
	L	ft³
	Contact time
	BV/h*	min

*Bed volumes per hour.

	Media volume
	L	ft³
	Water density
	kg/m³	lb/ft³
	Stock concentration
	%w/w	mg/L (ppm)
	Stock density
	kg/m³ (g/L)	lb/ft³
	Regenerant dosage*
	g/Lresin	lb/ft³resin
	Diluted concentration
	%w/w	mg/L (ppm)
	Contact time
	min	BV/h
	Stock regenerant
	L	gal
	kg	lb
	L/h	gal/h
	Diluted regenerant
	L	gal
	kg	lb
	L/h	gal/h
	Dilution water
	L	gal
	L/h	gal/h

*Chemical dosage per liter of resin at 100% concentration.

Gross flow
m³/h	gpm
Run length
h	days
Run volume
m³	gal
Feed water Hardness
mg/L CaCO3	meq/L
Feed water Sodium concentration
mg/L	meq/L
Design temperature
°C	°F
Desired safety factor¹
Regeneration level
g/Lresin
NaCl injection concentration
%
Resin type²
Not defined
Resin volume
L	ft³
Column internal diameter
mm	in
Column cylindrical height
mm	in
Resin height
mm	in
Pressure drop at design temperature
bar	psi
Final safety factor from column design¹
Contact time
min	BV/h
Hardness leakage
mg/L CaCO3	meq/L
NaCl @ 100% for regeneration
kg	lb
Diluted NaCl volume for regeneration
L	gal
Water consumption for regeneration
m³	gal
Overall regeneration duration
min	h
Regeneration step 1 - backwash³
m³/h	gpm
min	h
Regeneration step 2 - NaCl injection³
m³/h	gpm
min	h
Regeneration step 3 - displacement³
m³/h	gpm
min	h
Regeneration step 4 - fast rinse³
m³/h	gpm
min	h

Design based in the Ion Exchange resins engineering manuals.

¹ Safety factor over the calculated resin volume. The final safety factor might be higher because the model rounds up the resin volume. Typical: 1.05 to 1.15.

² Suggested resins: Amberlite™ IR120, Amberjet™ 1200, DOWEX™ Marathon™ C or DOWEX™ HCR-S.

³ Backwash in upflow direction. Operation, injection, displacement and rinse in downflow direction.

	Flow
	m³/h	gpm
	Diameter
	mm	in
	Rate
	m/h	ft/h

	Gross permeate flow
	m³/h	gpm
	Element area
	m²	ft²
	Element quantity
	elements
	Total area
	m²	ft²
	Flux
	L/m².h	gfd

	Feed flow
	m³/h	gpm
	Net product flow
	m³/h	gpm
	Concentrate flow
	m³/h	gpm
	Recovery
	%
	Concentration factor

	Average individual element recovery
	%
	Elements in series
	Total system recovery
	%

	Current flux
	L/m².h	gfd
	Net driving pressure
	bar	psi
	Current temperature*
	°C	°F
	Reference temperature*
	°C	°F
	Normalized permeability
	lmh/bar	gfd/psi

*If "current temperature" = "reference temperature", calculates without normalization.

	Media type¹

	Filtration rate/velocity
	m/h	ft/h
	Media height
	mm	in
	Dynamic viscosity (µ)
	Pa.s	cP
	Fluid density
	kg/m³	lb/ft³
	Mean particle effective size
	mm	in
	Porosity
	%
	Ergun coefficients
	Kv	Ki
	Head loss
	m	in

¹ Input values for particle sizes, porosity and Ergun coefficients.

Equations from MWH, 2005, Water Treatment Principles and Design 2nd edition.

	Media type¹

	Media height
	mm	in
	Desired expansion
	%
	Final height
	mm	in
	Dynamic viscosity (µ)
	Pa.s	cP
	Fluid density
	kg/m³	lb/ft³
	Particle density
	kg/m³	lb/ft³
	Mean particle effective size
	mm	in
	Settled bed porosity
	%
	Ergun coefficients
	Kv	Ki
	Backwash rate/velocity
	m/h	ft/h

¹ Input values for particle sizes, porosity and Ergun coefficients.

Equations from MWH, 2005, Water Treatment Principles and Design 2nd edition based in the Akgiray and Saatçi, 2001 models.

Disinfectant

Temperature
°C	°F
Log removal
log	%
CT
min.mg/L
Dosage*
mg/L (ppm)	%w/w
Contact time*
min	h

CT stands for Concentration vs Time and is defined by the EPA Interim Enhanced Surface Water Treatment Rule (IESWTR). CT Values interpolated from the EPA Disinfection Profiling and Benchmarking Guidance Manual Appendix C, 1999. *Not required for the CT calculation.

pH
Free chlorine
mg/L (ppm)	%w/w
Temperature
°C	°F
Log removal
log	%
CT
min.mg/L
Contact time
min	h

CT stands for Concentration vs Time and is defined by the EPA Interim Enhanced Surface Water Treatment Rule (IESWTR). CT Values calculated using the regression method according to the EPA Profiling and Benchmarking Guidance Manual Appendix E, 1999.

Oxidant

Process flow
m³/h	gpm
Fe2+ concentration
mg/L
Oxidant dosage (as 100%)*
mg/L
kg/h	lb/h
kg/day	lb/day
Alkalinity consumed
mg/L
kg/h	lb/h
kg/day	lb/day
Dry sludge production
kg/h	lb/h
kg/day	lb/day

*Stoichiometric values, no safety factors. Equations from ASCE/AWWA Water Treatment Plant Design, 3rd edition, 2003.

Oxidant

Process flow
m³/h	gpm
Mn2+ concentration
mg/L
Oxidant dosage (as 100%)*
mg/L
kg/h	lb/h
kg/day	lb/day
Alkalinity consumed
mg/L
kg/h	lb/h
kg/day	lb/day
Dry sludge production
kg/h	lb/h
kg/day	lb/day

*Stoichiometric values, no safety factors. Equations from ASCE/AWWA Water Treatment Plant Design, 3rd edition, 2003.

Process flow
m³/h	gpm
Chemical dosage
Aluminium Sulfate	mg/L
Ferric Sulfate	mg/L
Ferric Chloride	mg/L
PAC	mg/L %Al
Polymer	mg/L
Turbidity removed
NTU
Dry sludge production*
kg/h	lb/h
kg/day	lb/day

*Average values from real plant data. Equations from MWH, 2005, Water Treatment Principles and Design 2nd edition.

	BOD at the time t¹
	mg/L
	Ultimate BOD
	mg/L
	Time²
	days
	Deoxygenation rate constant
	1/day

¹ Usually the BOD₅, measured in the lab.

² 5 days if using the BOD₅.

	Present value
	Future value
	Interest rate
	% per period
	Number of payments
	Payment value

Ordinary annuity: Payments are required at the end of each period, compound interests.

	Present value
	Future value
	Interest rate
	% per period
	Number of payments
	Payment value

Annuity due: Payments are required at the beginning of each period, compound interests.

	Beginning value
	End value
	Number of periods
	Compound annual growth
	% per year

Interest rate

% year

% month

% day

	Principal
	Interest rate
	% per period
	Number of periods
	Simple interest
	Total value

Operation: Fill the blank fields until the results appear. Use the dot "." as the primary decimal separator.

Export results: If your system allows, just PRINT to get a formatted output from the open calculation models.

Tip: To get results from the lowest amount of inputs, fill from the top to the bottom.

Legend:

	Input or result field. Empty fields represent the number zero in the calculations.
	Invalid input value or character. Might not appear in some systems.
	Valid input for real time calculation.
	Read only, for results.
Check	Define were the results will be evaluated.
	Shortcut for a model that might help. Use the back button in your system to return to the source model.
m³/h	Shortcut for conversions. Use the back button in your system to return to the source model.

Plutocalc by Daniel Brooke Peig is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
The calculation results can be used for any purpose, including commercial projects, for free.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS, THE SPONSORS OR THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.