Operating cost
Steam Cost Calculator
Works out what a tonne of steam costs to produce, and compares fuels on the two numbers that matter to a plant head: how much steam you get per kilogram of fuel, and what that comes to per tonne.
Your plant
Actual evaporation, not the boiler's F&A nameplate rating.
Gauge pressure at the boiler.
Every degree hotter is a degree the fuel does not have to supply.
Lowest cost per tonne of steam
₹1,197/ tonne
on Indian steam coal — 5.43 kg of steam per kg
At 16 h/day and 26 days/month, that is about ₹9,96,210 a month, ₹1,19,54,520 a year.
Fuel comparison
| Fuel | Consumption | Steam per unit | ₹ / hour | ₹ / tonne steam |
|---|---|---|---|---|
| Indian steam coalIndicative | 368.4 kg/h | 5.43 kg / kg | ₹2,395 | ₹1,197 |
| Biomass briquetteIndicative | 407.7 kg/h | 4.91 kg / kg | ₹3,058 | ₹1,529 |
| Furnace oilIndicative | 138.5 kg/h | 14.44 kg / kg | ₹5,819 | ₹2,910 |
Indicative figures. Indicative industry figure — edit for your own fuel and contract price. Not a GyanTosh performance guarantee. Calorific values and efficiencies last reviewed 2026-08-04. Efficiency is stated on gross calorific value (GCV) basis throughout — a figure quoted on net calorific value is not comparable.
Use my own fuel prices and calorific values
Indian steam coal
Biomass briquette
Furnace oil
Behind the numbers
- Saturation temperature
- 185.5 °C
- Steam enthalpy h_g
- 2782 kJ/kg
- Feedwater enthalpy h_f
- 252 kJ/kg
- Useful heat delivered
- 12,08,420 kcal/h
This duty is equivalent to a boiler rated about 2,242 kg/h F&A 100 °C. Steam properties from IAPWS-IF97; efficiency figures are on gross calorific value basis.
How the calculation works
Four steps, from steam raised to rupees per tonne.
- 1Useful heatSteam raised, multiplied by the enthalpy rise from feedwater to saturated steam at working pressure. This is the heat the boiler must actually deliver.
- 2Heat inputUseful heat divided by boiler efficiency. The efficiency basis matters: 82% on gross calorific value is a strong number, 82% on net calorific value is unremarkable, and Indian tender disputes turn on the difference constantly. Everything here is on GCV basis and labelled as such.
- 3Fuel consumptionHeat input divided by the fuel's gross calorific value — kilograms per hour for solid and liquid fuels, standard cubic metres for gas.
- 4CostConsumption multiplied by your fuel price, then divided by tonnes of steam raised. The steam-to-fuel ratio is simply steam divided by fuel — the "kitna coal pe kitna steam" figure.
cost per tonne = (useful heat ÷ efficiency ÷ GCV) × price ÷ (steam ÷ 1000)
Common questions
What is a good steam-to-fuel ratio?
It depends almost entirely on the fuel, not on how good the boiler is. A high calorific value fuel gives a high ratio: furnace oil around 14–15 kg of steam per kg of fuel, natural gas a similar figure per standard cubic metre. Coal is typically 5–6, and wet biomass such as bagasse can be under 3. Comparing the ratio across different fuels tells you nothing about efficiency; comparing it against a benchmark for the same fuel does.
Why is the cheapest fuel per kilogram not the cheapest steam?
Because you buy fuel by weight and use it by calorific value. A fuel at half the price per kilogram but half the calorific value costs the same per tonne of steam, before allowing for the lower efficiency that wet, low-grade fuels usually bring with them. The cost per tonne of steam is the only figure that compares fuels fairly.
What is the difference between GCV and NCV efficiency?
Gross calorific value includes the latent heat of the water vapour formed when hydrogen in the fuel burns; net calorific value excludes it. Because the denominator is larger, an efficiency quoted on GCV is always the lower and more conservative number. A supplier quoting 90% without saying which basis is quoting a number that cannot be compared. Indian test methods for this are IS 13979 and IS 8753.
How much does feedwater temperature change the fuel bill?
Directly and substantially. Every degree the feedwater arrives hotter is a degree the fuel does not have to supply. Raising feedwater from 30 °C to 100 °C cuts the heat the boiler must add per kilogram of steam by roughly 12%, which is 12% off the fuel bill for the same steam output. This is why economisers, condensate recovery and deaerators pay back quickly.
What is a realistic cost of steam per tonne?
It depends on fuel price, calorific value, boiler efficiency, feedwater temperature and blowdown rate — which is why this returns a figure from your numbers rather than quoting one. Plants are routinely surprised: the cost of steam per tonne moves more with blowdown and condensate return than with the fuel contract they spend their time negotiating.