Steam Boiler Statistics

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This page holds detailed operational information about Steam Boilers.

Current (Railcraft 9.x.x.x)[edit]

In Railcraft 8.3.0.0, boilers were rebalanced, with their formulas changed significantly, most notably with fuel consumption during heat-up. Boilers no longer consume massive amounts of fuel when cold, but instead consume slightly less fuel when cold. On the other hand, boilers now produce less steam when not fully heated up, and high-pressure boilers now consume more fuel per unit steam than low-pressure boilers.

Overall, boilers are nerfed compared to the previous formula, but are still several times more efficient than tier 1 options such as the Hobbyist's Steam Engine on its own or the Generator.

Power generation[edit]

Steam engines generate 2 MJ/t for each low pressure boiler block. High pressure boiler blocks generate twice as much energy. The amount of steam, and thus power, generated is proportional to the temperature, except below 100 degrees, where no steam is produced.

Boilers Heat/c (L|H) Steam/c Steam/Heat (L|H) MJ/Heat* (L|H) EU/Heat* (L|H) RF/Heat* (L|H) Steam/t (L|H) MJ/t* (L|H) EU/t* (L|H) RF/t* (L|H)
1 10.7 12.7 160 14.95 12.60 2.99 2.52 9.35 7.87 29.91 25.20 10 20 2 4 6.25 12.50 20 40
8 80.0 96.0 1280 16.00 13.33 3.20 2.67 10.00 8.33 32.00 26.67 80 160 16 32 50.00 100.00 160 320
12 115.2 139.2 1920 16.67 13.79 3.33 2.76 10.42 8.62 33.33 27.59 120 240 24 48 75.00 150.00 240 480
18 162.0 198.0 2880 17.78 14.55 3.56 2.91 11.11 9.09 35.56 29.09 180 360 36 72 112.50 225.00 360 720
27 218.7 272.7 4320 19.75 15.84 3.95 3.17 12.35 9.90 39.51 31.68 270 540 54 108 168.75 337.50 540 1080
36 259.2 331.2 5760 22.22 17.39 4.44 3.48 13.89 10.87 44.44 34.78 360 720 72 144 225.00 450.00 720 1440

Assuming maximum temperature. Heat costs are reduced slightly when cold, but less steam is produced.

* after being converted using a Railcraft Engine (MJ/RF) or Steam Turbine (EU)

Fuel usage[edit]

Boilers Heat/t (L) Heat/t (H) Efficiency* (L) Efficiency* (H)
1 0.669 1.588 100% 84%
8 5.000 12.000 107% 89%
12 7.200 17.400 111% 92%
18 10.125 24.750 119% 97%
27 13.669 34.088 132% 106%
36 16.200 41.400 149% 116%

*Compared to 1LP Boiler


A LP boiler consumes 0.675 HU/t per boiler block, while a HP boiler consumes roughly 1.6 HU/t per boiler block. These values are reduced by 0.00625 HU/t and 0.0125 HU/t for each boiler block, respectively. Thus, a 36LP boiler consumes a third less fuel per steam (0.45 HU/t).

The formula for the amount of fuel consumed per block per boiler cycle is as follows: Fuel (hU) = 8 - 0.1*numTanks + 0.8*(heat/maxHeat) + 4*(maxHeat/1000)

The first term is a base term, while the second term is the size bonus, the third is the heat penalty, and the fourth is the pressure penalty. To get the fuel per tick, this term is multiplied by the number of boiler blocks, then divided by the length of the boiler cycle (16 for LP, 8 for HP). Note the following:

  • The pressure penalty makes HP boilers consume more fuel per steam than LP boilers, thus HP boilers are less fuel-efficient. This is compensated by the increased space and resource (iron) efficiency of HP boilers per unit power. A small LP boiler consumes 10.8 HU/cycle at full heat, while a small HP boiler consumes 12.8 HU/cycle (19% more).
  • Larger boilers are more efficient. In particular, the 36LP boiler is the most efficient boiler. A 36LP boiler consumes 7.2 HU/cycle, while a 36HP boiler consumes 9.2 HU/cycle (28% more than the 36LP).
  • Boilers consume slightly less fuel when not at full heat (0.8 HU/cycle less when cold).


The biggest change from legacy versions is that boilers no longer consume a massive amount of fuel to heat up. They still need fuel to heat up and still need the same amount of time, but it is no longer necessary to stockpile a large amount of fuel for the heatup process - one may start up a boiler as soon as fuel is being produced at a sufficient rate to maintain it at steady state.

High pressure boilers consume twice as much fuel per tick and have twice as far to heat up, so heating up a high pressure boiler take about four times as much initial fuel to hit their final temperature.

At full temperature, fuel efficiency can be further improved by not burning fuel constantly. Since the cooldown process around full temperature is 4 times faster than the heating process, up to 20% fuel can be saved by letting the temperature drop periodically upon reaching full temperature. Since steam production decreases with decreasing temperature, those periods have to be kept short to get an increased efficiency of close to 25%.

Resources needed to keep a chunkloaded, maximum size, low pressure boiler going for 1 day:

Resource Units / 24 hours
Fuel 583
Bio Fuel 1750
Coal Coke 8748
Coal, Charcoal 17496
Creosote Oil 5832
Lava 27994

Heat generation[edit]

Low Pressure to 100°C to 500°C
Boilers Ticks Fuel Ticks Fuel
1 440 276 4,519 2,941
8 3,522 16,420 36,156 175,576
12 5,282 35,361 54,233 378,775
18 7,924 74,214 81,350 797,332
27 11,885 148,930 122,025 1,608,672
36 15,847 232,674 162,700 2,530,393
High Pressure to 100°C to 1000°C
Boilers Ticks Fuel Ticks Fuel
1 419 627 9,141 14,170
8 3,352 37,754 73,130 855,690
12 5,028 81,929 109,694 1,859,485
18 7,542 174,158 164,542 3,961,711
27 11,313 357,494 246,813 8,164,156
36 15,083 574,457 329,083 13,181,268

Note: Values in the above table are based on integration and are approximate. Actual results will vary somewhat due to the discrete nature of the boiler formula (i.e. runs once per tick).

The time required to heat up a boiler is roughly 3.8 minutes per boiler block with a continuous supply of fuel. High pressure boiler blocks take twice as long because they have twice the maximum heat. The rate at which the temperature increases is a linear function of the temperature - from 4 degrees per second divided by the number of blocks at zero temperature, to 1 degree per second divided by the number of blocks at maximum temperature.

These numbers are reversed when losing heat due to insufficient fuel: 4 degrees per second at maximum temperature, 1 degree per second at zero temperature, again divided by the number of blocks.

Legacy (Railcraft 6.11.x.x - 7.1.x.x)[edit]

Power generation[edit]

Steam engines generate 2 MJ/t for each low pressure boiler block. High pressure boiler blocks generate twice as much energy. Temperature does not affect energy generation unless the temperature is below 100°C, in which case no energy is generated.

Boilers Heat/c Steam/c Steam/Heat MJ/Heat* EU/Heat* Steam/t (L|H) MJ/t* (L|H) EU/t* (L|H)
1 6.32 160 25.32 5.06 7.91 10 20 2 4 3.13 6.25
8 46.08 1280 27.78 5.56 8.68 80 160 16 32 25.00 50.00
12 65.28 1920 29.41 5.88 9.19 120 240 24 48 37.50 75.00
18 89.28 2880 32.26 6.45 10.08 180 360 36 72 56.25 112.50
27 114.48 4320 37.74 7.55 11.79 270 540 54 108 84.38 168.75
36 126.72 5760 45.45 9.09 14.20 360 720 72 144 112.50 225.00

Assuming maximum temperature. Heat costs can be up to 884% of values listed when cold (20°C)

* after being converted using a Railcraft Engine (MJ) or Steam Turbine (EU)

Fuel usage[edit]

Boilers Heat/t (L) Heat/t (H) Efficiency
1 0.395 0.790 100%
8 2.880 5.760 110%
12 4.080 8.160 116%
18 5.580 11.160 127%
27 7.155 14.310 149%
36 7.920 15.840 180%


Steam boilers consume ~0.4 HU/t for each boiler block when running at full temperature. There is then a 1.25% effeciency bonus per boiler block subtracted from this. So a full sized (36 block) furnace would use only 55% of the fuel. Whether or not the steam is being pumped out of the boiler does not affect the fuel consumed. High power boiler blocks consume twice the fuel and generate twice the energy, but do not get twice the efficiency bonus.

Steam boilers consume additional fuel when heating up. The amount of additional fuel consumed is equal to the standard fuel use plus ( 8 * <remaining heat percentage> ) This means that a cold boiler will consume almost 9 times as much fuel as a hot boiler. A boiler at half heat (250 for low pressure, 500 for high pressure) will consume 5 times as much fuel.

High pressure boilers consume twice as much fuel per tick and have twice as far to heat up, so heating up a high pressure boiler take about four times as much initial fuel to hit their final temperature.

At full temperature, fuel efficiency can be further improved by not burning fuel constantly. Since the cooldown process around full temperature is 4 times faster than the heating process, up to 20% fuel can be saved by letting the temperature drop periodically upon reaching full temperature. Since fuel consumption increases with decreasing temperature, those periods have to be kept short to get an increased efficiency of close to 25%.

Resources needed to keep a chunkloaded, maximum size, low pressure boiler going for 1 day:

Resource Units / 24 hours
Fuel 214
Bio Fuel 856
Coke Coal 2138
Coal, Charcoal 4277
Charcoal 8554
Creosote Oil 8554
Lava 13688

Heat generation[edit]

Low Pressure to 100°C to 500°C
Boilers Ticks Fuel Ticks Fuel
1 400 1,275 5,108 7,580
8 3,200 74,127 40,866 440,644
12 4,801 157,981 61,300 936,205
18 7,201 323,733 91,949 1,920,345
27 10,800 621,357 137,926 3,693,443
36 14,400 917,028 183,900 5,450,849
High Pressure to 100°C to 1000°C
Boilers Ticks Fuel Ticks Fuel
1 400 2,695 10,317 30,921
8 3,200 157,056 82,533 1,802,285
12 4,801 334,268 123,799 3,829,687
18 7,201 685,360 185,700 7,856,377
27 10,800 1,316,786 278,550 15,110,593
36 14,400 1,943,419 371,400 22,301,396

The time required to heat up a boiler is 4.25 minutes per boiler block with a continuous supply of fuel. High pressure boiler blocks take twice as long because they have twice the maximum heat. The rate at which the temperature increase happens is 4 degrees per second for the first quarter (20 to 125 degrees in the low pressure boiler,) 3 degrees per second for the second quarter, 2 degrees per second for the third, and 1 degree per second for the last quarter divided by the number of boiler blocks.

These numbers are reversed when losing heat due to insufficient fuel: 4 degrees per second for the last quarter, 3 for the third, 2 for the second, and one for the first (also divided by the number of blocks.)