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Plant Engineering Calculator

Updated Sep 18, 2026

Boiler Steam-to-Fuel Ratio Calculator — kg Steam/kg Fuel & Specific Fuel

Calculate steam-to-fuel ratio, specific fuel consumption and optional benchmark gap from measured steam and fuel mass flows.

Live calculationWorking shownPrivate in browser

Inputs

Results

Steam/fuel 13.33 kg/kg
Specific fuel 0.0750 kg/kg
Fuel per tonne 75.0 kg/t
Benchmark gap -0.67
More actions

Shared links reopen these inputs. Recent and saved calculations stay in this browser unless you clear site data.

Formula

SFR=msteam/mfuel; SFC=mfuel/msteam.

Your calculation, step by step

These steps use the values currently entered above so the result can be checked independently.

  1. 1.Steam-to-fuel ratio = 8000.00 ÷ 600.00 = 13.3333 kg steam/kg fuel.
  2. 2.Specific fuel = reciprocal = 600.00 ÷ 8000.00 = 0.075000 kg fuel/kg steam.
  3. 3.Fuel per tonne steam = 0.075000 × 1000 = 75.000 kg/t.
  4. 4.Gap to entered benchmark 14.000 kg/kg = 13.3333 − 14.000 = -0.6667 kg/kg.

How to use this calculator

  1. Enter measured or design values using the units shown beside each field.
  2. Review the live results and the substituted calculation steps before using the estimate.
  3. Check the assumptions below, then continue to a related calculator when the next engineering decision needs another model.

Worked example

8,000 kg/h steam from 600 kg/h fuel gives 13.33 kg steam/kg fuel.

Assumptions and limits

  • Mass-flow ratio alone does not normalize fuel heating value, feedwater temperature or steam condition.
  • Use boiler efficiency/fuel-comparison tools for thermodynamic normalization.

How to interpret the result

Treat the primary result as an engineering screening value, then use the secondary outputs to understand scale, energy or operating impact. Confirm site measurements, equipment limits and applicable standards before making a design or control change.

Questions engineers ask

Why can steam/fuel ratio be misleading between different fuels?

A mass ratio does not normalize fuel heating value. One kilogram of natural gas, oil, coal or biomass can contain very different energy, so mass SFR is best used for the same boiler/fuel basis over time.

What else shifts steam-to-fuel ratio besides boiler efficiency?

Steam pressure/condition, feedwater temperature, blowdown, fuel heating value, load and measurement quality all change the ratio. Use a thermodynamic boiler-efficiency calculation for normalized comparison.

Why show specific fuel and fuel per tonne too?

They are reciprocal/normalized views of the same mass balance and are often easier for operations teams to benchmark against a fuel budget or historical tonne-of-steam target.

Continue the calculation

Use the next calculator in the same engineering workflow instead of restarting from search.

boiler efficiencyboiler fuel comparisonboiler steam output
Methodology. MAXScanner shows the governing formula, entered values and calculation outputs so the estimate is auditable. The calculator is a screening aid; assumptions and equipment-specific limits remain part of the engineering review.