Steam boost, continuous steam and pressure explained
Learn how steam boost, continuous steam and generator pressure differ, why grams and grams per minute cannot be ranked together, and what to compare.
What each steam number describes
Read the label beside the number first. A product listing can put continuous output, steam boost and pressure next to each other. They answer different questions about what the iron or generator can do.
Scroll sideways to see all the units and uses.
| Specification | Typical unit | What it tells you |
|---|---|---|
| Continuous steam | Grams per minute (g/min) | The manufacturer’s stated rate for sustained steam under its test conditions. |
| Steam boost or steam shot | Grams (g) or grams per minute (g/min) | A separate figure for a brief extra steam release. Check whether the unit is a mass or a rate. |
| Pressure | Bar | The pressure at the point or part of the system the manufacturer specifies. |
A separate steam generator often lists all three figures. A conventional iron may publish just the continuous rate and the boost, alongside its electrical wattage. Watts describe electrical power. Use the actual steam specifications to discuss steam.
Continuous steam describes a rate
A figure like 50 g/min means a rate of 50 grams over a minute at the stated conditions. If the manufacturer says up to 50 g/min, read that as a maximum claim for the appliance. Steam controls, economy modes and interruptions affect how much steam you use during an ordinary session.
For example, if an iron maintained a steady 40 g/min for exactly 15 seconds, that rate would represent 10 g over the interval. This is how a rate and a duration relate. It does not predict the amount from a particular trigger press or the water you will use ironing a shirt. A tank might last much longer than a simple division suggests because you stop for collars, move the garment and use different settings.
The Philips PerfectCare Compact GC7842/46 shows the three quantities on one specification sheet. Philips lists continuous steam up to 120 g/min, a boost up to 400 g and maximum pump pressure of 6.5 bar. The 120 g/min figure is the starting point if you are interested in regular steaming over several pieces of fabric. The other two figures describe different aspects of the same appliance.
Philips PerfectCare Compact GC7842/46
The base is 19.3 cm wide, with a 1.5 L tank and automatic temperature for ironable fabrics.
Good for
Good for regular ironing when cupboard width is tight and you can take a jug to the base for refills.
Bear in mind
The tank stays in the base. Check the 1.2 kg handpiece and allow room for the base and hose.
- 1.5 L, fixed
- 120 g/min
- 400 g
- 19.3 × 37.3 × 22.3 cm
Boost is a separate, brief steam release
Use a boost when the garment permits steam and there is a crease you want to work on. The control might be a dedicated button or a particular sequence on the steam trigger. Look up how the exact appliance activates it, and give it the recovery time the maker specifies between shots. A burst can lose its usefulness if the soleplate is too cool.
Manufacturers sometimes express boost in grams and sometimes as a flow rate. The Tefal Ultimate Turbo Pro FV5696G0 is a conventional iron with a quoted boost of up to 270 g/min and a separate continuous rating of up to 50 g/min. Tefal describes the boost as a short function and advises waiting a few seconds between uses. The two published rates describe different modes.
This exact model was unavailable when reviewed in November 2026.
Tefal Ultimate Turbo Pro Anti-Scale FV5696G0
A 300 ml tank and removable scale collector suit regular ironing. The dial selects the fabric setting and the iron adjusts steam to match.
Good for
Regular pressing when you want an accessible collector and a separate dry ironing setting.
Bear in mind
Unplug, empty and cool the iron before removing the collector. Follow the model’s water and cleaning instructions.
- 300 ml tank
- 50 g/min continuous steam
- Removable collector
- 2 m cord
Comparing that Tefal figure directly with Philips’s 400 g boost would mix a rate and a mass. To work out how much water a burst represented from a quoted rate, you would need the duration and know how the rate was measured over that burst. Two models that list the same unit may also use different test methods. Read the exact manufacturer document and leave a specification out of a head-to-head comparison if the unit or method is unclear.
If a listing drops the unit or uses different units in its headline and specification table, check the manufacturer’s sheet for the exact model suffix. Keep the figures in their original units. Converting a number by guessing how long a shot lasts can give you a precise-looking answer with no clear meaning. Even where two quoted boost rates match, the way each iron delivers a shot and the recovery time between presses can differ.
Bar describes pressure
One bar equals 100 kilopascals. Pressure and flow can both affect a steam system, but one does not tell you the other. Philips calls the 6.5 bar figure on the GC7842/46 a maximum pump pressure. It is different from the amount of steam the iron produces over a minute. If a second listing calls its number boiler pressure, or says only “pressure”, check what it actually measures before making a comparison. BIPM SI Brochure.
For a generator, compare the type of pressure figure along with continuous output, tank access and whether the iron and hose are easy to use on your board. Read more about which format fits your routine in steam generator vs steam iron.
Match the steam setting to the job
For a series of large ironable panels, sustained steam and water capacity may matter more than a boost button. Compare continuous figures with each other, then check where the base will sit, how to refill and what cleaning the model needs. For a few shirts, look at the soleplate tip and the ease of changing heat and steam. For a cord-free handpiece, include how often it has to return to its dock. Cordless steam irons.
Read the care label even if the iron advertises a large boost. A low-temperature garment can need dry pressing or a restricted steam setting. Test the permitted method on an inconspicuous area when you are unsure how the finish will respond. Clothes care symbols explained.
If the boost no longer works, check for water, a ready indication and the correct trigger sequence before assuming a fault. Use the manufacturer’s water and scale-care instructions. Persistent spitting or a warning light calls for the model’s troubleshooting steps. Steam generator iron not steaming.
Specification and use references
Frequently asked questions
What does steam boost mean on an iron?
It is a short extra release of steam used on a stubborn crease when the garment and appliance instructions allow it. The control and time between shots depend on the model.
Is 400 g of steam boost stronger than 270 g/min?
Those numbers describe different quantities. Grams measure mass and grams per minute measure a rate. You would need the duration and a comparable test method to relate the two.
Does 50 g/min mean the iron always uses 50 g of water each minute?
No. An up-to rating describes the maker’s stated output under specified conditions. Setting, trigger use and pauses affect the output over a session. A tank size and an output rating alone cannot tell you the refill interval.
What does bar mean on a steam generator iron?
Bar is a unit of pressure. Look for wording such as maximum pump pressure or boiler pressure. It describes a different quantity from steam output in grams per minute.
Which matters more, boost or continuous steam?
For steady use on several garments, compare continuous output first. For an occasional deep crease on fabric that permits steam, look at the boost control. Also check temperature settings, the board and where you can put the iron down.
Why has steam boost stopped working?
Check water level, the heat or ready indication, the model’s boost instructions and whether scale maintenance is due. Some irons need recovery time between shots. If it keeps leaking or fails after normal checks, stop and follow the maker’s service advice.