What This Tool Converts

This free scientific unit converter covers ten categories used across agriculture, soil science, environmental research, and everyday fieldwork: mass, area, volume, pressure, temperature, concentration, elemental-to-oxide nutrient conversion, fertilizer application rate, greenhouse gas (GHG) flux, and soil bulk density. Every conversion factor and formula below is a standard, publicly documented method — not an invented number — but this is still a calculation aid, not a certified laboratory instrument.

Every Conversion This Tool Supports

Whether you need a quick unit converter for a lab report or a full scientific unit converter for agriculture and soil science, here’s everything covered:

• Mass converter — kg to lb, mg to g, tonne to kg, quintal to kg, and a maund to kg converter for Pakistani and Indian agricultural weights, plus teragram and petagram for large-scale mass figures.
• Area converter — acre to hectare, hectare to acre, a kanal to marla converter and marla to kanal converter for Pakistani land measurements, plus m² and ft² conversions.
• Volume converter — liters to gallons, an acre-foot to liters converter and acre-inch converter for irrigation water volume calculations.
• Pressure unit converter — a psi to kPa converter, bar to atm, and mmHg/Torr conversions, useful for soil water potential (field capacity and wilting point).
• Celsius to Fahrenheit converter and Fahrenheit to Celsius converter, plus Kelvin conversions.
• Concentration converter — a ppm to mg/L converter, ppm to percent converter, mg/kg to ppm converter, and a mol/L to mg/L converter for molar concentrations.
• Elemental to oxide converter — a P to P2O5 converter and K to K2O converter for fertilizer nutrient analysis, plus Ca to CaO and Mg to MgO.
• Fertilizer application rate calculator — a kg/ha to kg/acre converter and lb/acre to kg/ha converter, including Pakistani units like kg/kanal and 50kg-bag/acre.
• GHG flux calculator — an N2O to N2O-N converter for greenhouse gas emission reporting, converting between ng m⁻² s⁻¹, µg m⁻² h⁻¹, and kg ha⁻¹ yr⁻¹.
• Soil bulk density calculator and soil carbon stock calculator — a mg/kg to kg/ha converter using bulk density and sampling depth.

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Mass, Area, Volume, Pressure & Application Rate

These five categories all work the same simple way: every unit is defined as a multiple of one base unit (grams for mass, square meters for area, liters for volume, Pascals for pressure, kg/ha for application rate), so converting between any two units is one calculation.

This tool includes several units that are easy to mix up or hard to find elsewhere in one place:

• Maund (the standard Pakistan/India mass unit, ≈37.32 kg) alongside metric and imperial mass units
• Kanal and marla (Pakistani land units) alongside acres, hectares, and other area units
• Teragram (Tg) and petagram (Pg) for large-scale mass figures, such as national or global totals
• Acre-inch and acre-foot, the standard irrigation-volume units used in water requirement calculations
• Kilopascals and bar, commonly used for soil water potential (field capacity, wilting point)
• Kg/kanal, kg/marla, and 50kg-bag/acre for fertilizer and amendment rates as commonly written on Pakistani farm inputs

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Temperature

Temperature can’t use the simple multiply-and-divide method above, since none of the three common scales start at the same zero point. This tool converts through Celsius as a fixed reference point:

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Concentration

Concentration conversions fall into three groups, and mixing them up is one of the most common sources of error in lab and field reporting.

Mass-basis units (exact, no assumptions)

ppm, mg/kg, and µg/g are exact synonyms — 1 ppm always equals 1 mg/kg always equals 1 µg/g, with no conversion factor needed, because all three describe a mass of substance per mass of sample.

Volume-basis units (require a density assumption)

Units like mg/L, µg/mL, and g/L describe mass per volume of solution, not per mass of solution — so converting between a mass-basis unit and a volume-basis unit technically requires knowing the solution’s density.

Molar and charge-equivalent units

mol/L and mmol/L can’t convert to a mass-based unit without knowing the substance’s molar mass:

meq/L (milliequivalents per liter — common in soil cation exchange and water hardness reporting) additionally needs the ion’s valence (charge):

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Elemental ↔ Oxide Conversion

Fertilizer nutrient content is reported two different ways depending on the country and lab: as the pure element, or as its oxide form. This tool converts between them using each nutrient’s exact molecular weight ratio:

Elemental	Oxide	Elemental → Oxide	Oxide → Elemental
P (Phosphorus)	P₂O₅	× 2.2913	× 0.4364
K (Potassium)	K₂O	× 1.2046	× 0.8302
Ca (Calcium)	CaO	× 1.3992	× 0.7147
Mg (Magnesium)	MgO	× 1.6583	× 0.6030

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GHG Flux Conversion

Greenhouse gas flux measurements (from chamber-based sampling with GC, Picarro, or LI-COR systems) vary along two separate dimensions, and this tool lets you convert both at once.

Element basis vs. whole-molecule basis

N₂O flux is usually reported as N₂O-N (the mass of nitrogen only), not the mass of the whole N₂O molecule — the same applies to CH₄-C and CO₂-C. Converting between the two uses each gas’s exact molecular weight ratio:

Gas	Element → Molecule	Molecule → Element
N₂O (as N₂O-N)	× 1.5711	× 0.6365
CH₄ (as CH₄-C)	× 1.3354	× 0.7488
CO₂ (as CO₂-C)	× 3.6641	× 0.2729

Time and area basis

Flux is also reported across very different time/area scales — from a chamber measurement in ng m⁻² s⁻¹ up to a cumulative annual figure in kg ha⁻¹ yr⁻¹. This tool converts between all of them using µg m⁻² h⁻¹ as the internal reference point.

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Bulk Density Calculator (Soil Stock Estimation)

This calculator converts a lab-reported soil concentration into a per-hectare stock — the standard way to express nutrient or carbon stocks in soil science:

This is the same “furrow slice” style formula used throughout soil science for calculating nutrient and soil organic carbon stocks — the 0.1 constant comes directly from converting the soil column’s volume and mass units into a per-hectare basis.

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Why These Are Estimates

Every formula and factor in this tool is a standard, published method — not a made-up number — but results should still be treated as working estimates for planning and coursework, not as calibrated laboratory or legal-grade figures. Where a formula depends on an assumption (solution density in Concentration, the 365-day year in GHG Flux), that assumption is stated clearly wherever it applies.