Specs from the makers' own documentation Battery compatibility built in UK retailer prices, updated daily 25+ years of trade experience
‹ All Milwaukee M18 batteries
M18 Milwaukee M18B4
Fits
72 Milwaukee M18 toolsSee them ›
Charges
52 min on 7 of the 11 chargers Milwaukee lists for itCharge times ›
Specs
From Milwaukee's own documentationChecked 14 Jun 2026
Milwaukee · M18 platform

Milwaukee M18B4 18V 4.0Ah REDLITHIUM battery

4.0Ah 72Wh 0.7kg Fuel gauge

M18 REDLITHIUM 4.0Ah (72Wh) general-use pack with fuel gauge. Same 0.70kg as the 5.0Ah.

Adds it to My Tools, kept on this device
Lowest price we track
£57.95at Tooled Up · + £6.95 delivery
View at Tooled Up ›
Compare retailersTotal with delivery
Tooled Up Lowest£57.95 + £6.95 delivery£64.90View ›
My Tool Shed£57.95 + £6.95 delivery£64.90View ›
Prices from UK retailer feeds, updated daily.We may earn a commission
4.0AhCapacitymaker figure
72WhEnergymaker figure
0.7kgWeightmaker figure
103Wh/kgEnergy for its weightworked out
£14.49Per Ahat the lowest price we track

Other sizes in this range

Same fit, same tools. Bigger packs run longer and weigh more. Pick the size for the job.

Compare these sizes ›All Milwaukee M18 batteries ›
ModelSizeEnergyWeightLowest pricePer Ah
M18B2 2.0Ah 36Wh 0.4kg £56.95 £28.48 per Ah
M18HB3 3.0Ah 54Wh 0.7kg £64.95 £21.65 per Ah
M18B4 This one 4.0Ah 72Wh 0.7kg £57.95 £14.49 per Ah
M18B5 5.0Ah 90Wh 0.7kg £59.95 £11.99 per Ah
M18B5-CR 5.0Ah 90Wh 0.7kg £87.95 £17.59 per Ah
M18HB5 5.0Ah 90Wh 0.79kg No price yet
M18HB5-CR 5.0Ah 90Wh 0.79kg No price yet
M18HB5.5 5.5Ah 99Wh 1.1kg £99.95 £18.17 per Ah
M18FB6 6.0Ah 108Wh 1.03kg £199.95 £33.33 per Ah
M18FB8 8.0Ah 144Wh 1.08kg No price yet
M18FB12 12.0Ah 216Wh 1.51kg £239.95 £20.00 per Ah

Prices are the lowest we track at UK retailers, updated daily. Weights from Milwaukee. Energy is Milwaukee's figure, or worked out from volts × Ah where they don't publish one.

Full specs

From Milwaukee's own documentation, checked 14/06/2026. "Not listed" where Milwaukee doesn't publish a figure.

Voltage18V
Capacity4.0Ah
Energy72Wh
ChemistryLi-ion (cylindrical)
Cell typeNot listed
Weight0.7kg
Size (L × W × H)Not listed
Fuel gaugeYes
ExtrasREDLINK Intelligence
PlatformMilwaukee M18
Model codeM18B4

Charge times

Milwaukee's own figures, fastest first. Each charger opens its own page.

M12-18FCMulti-voltage fast charger
52 min
£59.95 at Tooled Up ›
M18DFCDual-bay rapid charger
52 min
£99.95 at Tooled Up ›
M18PC66-bay rapid charger (2 at once)
52 min
£238.95 at Tooled Up ›
M18DBSCDual-bay super charger (simultaneous, adaptive)
52 min
No retailer price yet
M18MDBSCMobile dual-bay super charger (simultaneous, adaptive)
52 min
No retailer price yet
M18MPC6Six-bay rapid charger (2 at once)
52 min
No retailer price yet
M12-18GBC4Four-bay gangbox charger (2 at once)
52 min
No retailer price yet
M12-18ACIn-car charger
1 hr 20 min
£79.95 at Tooled Up ›
M1418C66-bay sequential charger
1 hr 20 min
£109.95 at Tooled Up ›
M1418C6-110V6-bay sequential charger
1 hr 20 min
£109.95 at Tooled Up ›
M18TCUSB-C mini charger and power supply
1 hr 20 min
No retailer price yet

Milwaukee's own figures. We may earn a commission

Fits these tools

Every Milwaukee M18 tool takes this pack. It won't fit other brands' tools.

All 72 Milwaukee M18 tools ›
Circular Saws8 tools › Angle Grinders8 tools › Reciprocating Saws6 tools › Site Vacuums5 tools › Combi Drills5 tools › SDS+ Hammer Drills4 tools › Second Fix Nailers3 tools › Jigsaws3 tools › Impact Drivers3 tools › Multi-Tools2 tools › Dual Action Polishers2 tools › Random Orbital Sanders2 tools › First Fix Nailers2 tools › SDS Max Hammer Drills2 tools › Dust Extractors2 tools › Angle Drills2 tools › Impact Wrenches2 tools › Table Saws1 tool › Rotary Polishers1 tool › Belt Sanders1 tool › Sheet & Palm Sanders1 tool › Trim Routers & Edge Trimmers1 tool › Routers1 tool › Planers1 tool › Brad Nailers1 tool › Handheld Vacuums1 tool › Plunge Saws1 tool › Metal Cutting Saws1 tool ›

4.0Ah packs from other brands

Only useful if you haven't picked a platform yet: packs don't swap between brands. Shown on neutral figures only.

Not sure which platform? ›
BatteryEnergyWeightWh per kgLowest pricePer Ah
MilwaukeeM18B4 72Wh 0.7kg 103 £57.95£14.49
BoschPROCORE18V-40 72Wh 0.52kg 140 £54.99£13.75
Bosch Green1600A011T8 72Wh 0.64kg 113 £59.95£14.99
DeWaltDCB182 72Wh 0.61kg 118 £49.95£12.49
Einhell4511396 72Wh 0.67kg 107 £36.95£9.24
FestoolBP18Li4.0HPC 72Wh 0.6kg 120 £155.95£38.99

M18B4 questions

Which tools does the M18B4 fit?

It fits every Milwaukee M18 tool. It won't fit other brands' tools.

How long does the M18B4 take to charge?

From Milwaukee's own figures: M12-18FC: 52 min, M18DFC: 52 min, M18PC6: 52 min, M18DBSC: 52 min, M18MDBSC: 52 min, M18MPC6: 52 min, M12-18GBC4: 52 min, M12-18AC: 1 hr 20 min, M1418C6: 1 hr 20 min, M1418C6-110V: 1 hr 20 min, M18TC: 1 hr 20 min.

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