Refrigerant charge limit and minimum room size
How much refrigerant a room can take, or how big the room must be for your charge.
Biggest charge for this room
3.25kg R32
0 kg7.98 kg · EN 378-1
Work out
Where the indoor unit sits
Floor area of the room (m²)Length × width, off your tape measure
On a multi-split, check the smallest room with an indoor unit in it, against the whole system's charge.
This is a guide. The manufacturer's installation manual comes first: some ask for more room than this, and many print their own minimum floor area table. Use theirs.
How this is worked out (EN 378-1)
Worked out: 2.5 × 0.307^1.25 × 1.8 × √10.00 = 3.25 kg; 0.75 × 0.307 × 1.8 × 10.00 = 4.14 kg; the smaller one counts
Where these numbers come from
- The two room formulas (EN 378-1:2016 C.1 and C.2) and the unit heights: floor 0.6 m, wall 1.8 m, window 1 m, ceiling 2.2 m: EN 378 summary, pp.5 and 7; Midea R32 safety manual, p.3; Samsung installation manual AR**CXKA, p.4.
- The second rule, area not less than charge ÷ (0.75 × LFL × height), and R32's LFL of 0.307 kg/m³: Panasonic service manual PAPAMY2212036CE, p.41.
- No minimum room size up to 1.842 kg of R32 (6 m³ × LFL): Daikin installer reference guide 4P513661-9J, pp.9–10; Samsung installation manual AR**CXKA, p.4.
- The 4, 6 and 26 m³ × LFL limits, and R1234yf's LFL of 0.289 kg/m³: Tecumseh, 2L refrigerant charge limits, pp.5–6.
- R410A: no more than 0.44 kg for every m³ of room (EN 378): Daikin R-32 VRV safety standards guide, pp.5–6.
- Older R32 manuals start asking for a room from 1.22 kg and can ask for a little more room than this. Their table wins: Fujitsu installation manual ASYH30KMTB, pp.1–2.
- Not here yet: R454B, because published figures for it disagree, and R134a, because no manual we found says which EN 378 limit applies to a room.
- Figures checked 17 October 2026.