Convert kg of Hydrogen to kWh
| kg | kWh |
|---|---|
| 0.5 | 19.69 |
| 1 | 39.38 |
| 1.5 | 59.08 |
| 2 | 78.77 |
| 3 | 118.2 |
| 5 | 196.9 |
| 10 | 393.8 |
| 20 | 787.7 |
| 50 | 1,969 |
| 100 | 3,938 |
Each row uses the same factor as the converter above: 1 kg = 39.38 kWh.
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A kilogram of hydrogen holds 39.38 kWh on the gross basis, or 33.32 kWh on the net. That is roughly three times as much energy as a kilogram of diesel — more than any other fuel on this site by weight. It is also the fuel where the choice between those two figures matters most, because the gap between them is the widest of any fuel and the two conventions turn up side by side in the same documents.
To convert kilograms of hydrogen to kilowatt-hours, multiply by 39.38 on the gross calorific value, or by 33.32 on the net. So 100 kg is 3,938 kWh gross or 3,332 kWh net. Reversed, a kilowatt-hour is about 0.025 kg of hydrogen.
kWh = kg × calorific value per kg. Reverse: kg = kWh ÷ calorific value. The underlying figures are 141.781 GJ per tonne gross and 119.953 net, read live and converted by the fixed 1/3.6 that takes gigajoules per tonne to kilowatt-hours per kilogram.
| Hydrogen | Gross (GCV/HHV) | Net (NCV/LHV) |
|---|---|---|
| 1 kg | 39.38 kWh | 33.32 kWh |
| 5 kg (car tank) | 197 kWh | 167 kWh |
| 100 kg | 3,938 kWh | 3,332 kWh |
| 1,000 kg (one tonne) | 39,380 kWh | 33,320 kWh |
How to convert kg of hydrogen to kWh
Multiply by 39.38 for gross, or 33.32 for net. A passenger fuel-cell car carrying about 5 kg holds roughly 197 kWh gross — several times the usable capacity of a typical battery electric car, in a tank a fraction of the weight.
The anchor is forty: a kilogram of hydrogen is around forty kilowatt-hours gross, or a third less on the net basis.
kWh to kg of hydrogen
Divide by the same figure. 1,000 kWh is about 25 kg of hydrogen gross, or 30 kg net — a useful direction when sizing electrolyser output or storage against a known energy demand.
The best fuel by weight, the worst by volume
Hydrogen’s energy density per kilogram is exceptional. Per cubic metre it is dismal, and that contradiction is the entire engineering problem with using it.
| Fuel | kWh per kg (gross) | Relative to hydrogen |
|---|---|---|
| Hydrogen | 39.38 | — |
| LPG | 13.70 | about a third |
| Diesel | 12.66 | about a third |
| Coal (house) | 8.37 | about a fifth |
A kilogram of hydrogen at atmospheric pressure occupies roughly eleven cubic metres — the volume of a small room. Which is why hydrogen is stored compressed to hundreds of bar, or chilled to liquid, and why the storage and distribution question dominates almost every practical discussion of it. This converter deliberately works in kilograms and not in cubic metres, because a volume of hydrogen means nothing without a stated pressure and temperature.
Gross or net — the widest gap of any fuel
The two calorific bases are 15.4 per cent apart for hydrogen, measured as a share of the gross figure. Compare natural gas at 9.8 per cent, diesel at 6.0 and petrol at 5.3.
The reason is structural. Gross and net differ over whether the energy carried away in exhaust water vapour is counted, and hydrogen is nothing but hydrogen — burning it produces only water, and more of it per unit of energy than any hydrocarbon. So the quantity in dispute is larger here than anywhere else.
Fuel-cell and electrolyser efficiencies are conventionally quoted against the net (LHV) value, while boiler and reporting conventions use gross (HHV). Both appear routinely in the same document, and a hydrogen efficiency quoted without saying which basis it uses is ambiguous by about a sixth — enough to turn a 65 per cent efficiency into a 77 per cent one on paper alone. Whenever you compare two hydrogen figures, check the basis before you check anything else. One more trap: the same 15.4 per cent gap is often quoted as 18.2 per cent, which is the identical difference measured against the net value instead of the gross. Both are correct; mixing them is not.
Green, blue and grey hydrogen all convert identically
A kilogram of hydrogen is the same molecule with the same energy content whether it came from electrolysis powered by wind, from steam methane reforming with carbon capture, or from unabated natural gas. The colours describe the production pathway and therefore the emissions, not the calorific value. So this converter has no colour selector, and it should not — every route gives 39.38 kWh per kilogram gross. What differs is the carbon footprint of producing that kilogram, which is a separate calculation entirely.
Where this conversion is needed
- Electrolyser sizing — converting a hydrogen output target in kilograms into the electrical input it implies, before efficiency is applied.
- Fuel-cell vehicles — comparing a hydrogen tank against a battery, which is only meaningful in energy terms.
- Industrial fuel switching — assessing hydrogen against natural gas for process heat requires both on a common basis.
- Energy system modelling — where hydrogen has to sit alongside electricity and gas in one balance.
Burning hydrogen produces no carbon dioxide at all — only water — so a combustion emission factor is not the interesting number here. Almost all of hydrogen’s climate impact sits upstream, in how it was produced, and that varies by more than an order of magnitude between pathways. For the fuels this might displace, see the stationary combustion calculator; for the electricity an electrolyser would draw, the Scope 2 electricity calculator.
Frequently Asked Questions
About 39.38 kWh on the gross calorific value, or 33.32 kWh on the net. That is roughly three times the energy in a kilogram of diesel — more per kilogram than any other common fuel.
Because that is the net calorific value rather than the gross. Fuel-cell and electrolyser work conventionally uses the net figure, while boiler and reporting conventions use gross. Both are correct for hydrogen; they differ over whether the energy carried away in the water vapour produced is counted.
Because hydrogen is nothing but hydrogen. Burning it produces only water, and more water per unit of energy than any hydrocarbon, so the quantity the two bases disagree about is larger. The gap is 15.4 per cent of the gross value, against about 9.8 for natural gas and 6.0 for diesel.
Both, depending on what you divide by. It is 15.4 per cent of the gross value and 18.2 per cent of the net value — the same absolute difference expressed two ways. This page uses the share of gross throughout, so that hydrogen can be compared like for like against the other fuels here. Mixing the two bases across sources is a common way to end up comparing figures that are not comparable.
No. The colours describe how the hydrogen was produced, not what it is. A kilogram is the same molecule with the same energy content whether it came from electrolysis, from steam methane reforming with carbon capture, or from unabated natural gas. What differs is the carbon footprint of making it, which varies by more than an order of magnitude between routes.
A passenger fuel-cell car typically carries about 5 kg, which is roughly 197 kWh on the gross basis or 167 kWh net. That is several times the usable capacity of a typical battery electric car, in a tank weighing a fraction of what the battery would.
Because a volume of hydrogen means nothing without a stated pressure and temperature. At atmospheric pressure a kilogram occupies about eleven cubic metres — the volume of a small room — which is why hydrogen is stored compressed to hundreds of bar or chilled to liquid. Mass is the only stable way to quantify it.
Burning hydrogen produces no carbon dioxide at all — the only combustion product is water. Almost all of hydrogen’s climate impact sits upstream in how it was produced, which is why the production pathway matters so much more than the combustion does, and why a combustion emission factor is not the useful number for this fuel.