Power Tools Never Buy Cordless? The Truth

The short answer is no: you should not never buy cordless power tools. Cordless tools are the right choice for most people in most situations today, but corded tools still win for continuous, heavy-duty work where runtime and raw power matter more than portability. The real question is not “cordless vs. corded” but “which tool for which job,” and this article breaks down the trade-offs so you can decide with your own projects in mind.

Formula

The calculator above estimates how long a cordless tool runs on one battery and how many batteries you need for a day of work. The runtime formula is:

Runtime (hours) = Battery capacity (Wh) ÷ Tool power draw (W)

Where:

• Battery capacity (Wh) – the energy stored in the battery, in watt-hours. A typical 18V battery with 6Ah capacity stores 18 × 6 = 108 Wh.
• Tool power draw (W) – the average power the tool uses while running. This varies a lot with load: a drill under light load might draw 200 W, while a circular saw cutting hardwood can draw 1500 W or more.

The number of batteries needed per day is simply the total work time divided by the runtime per battery. This assumes you start with fully charged batteries and that you don’t recharge during the day.

Worked Example

Using the default values from the calculator:

• Work time per day = 2 hours
• Tool power draw = 500 W
• Battery capacity = 108 Wh

First, compute runtime per battery:

108 Wh ÷ 500 W = 0.216 hours ≈ 13 minutes

Then, batteries needed per day:

2 hours ÷ 0.216 hours = 9.26 ≈ 10 batteries

So with a 500 W tool and a standard 108 Wh battery, you would need about 10 fully charged batteries to work for 2 hours continuously. That’s why cordless tools are impractical for sustained heavy use – you’d need an enormous battery fleet or frequent recharging.

Why Cordless Tools Have Improved

Twenty years ago, cordless tools were weak, heavy, and had short runtimes. Today, brushless motors and lithium-ion batteries have transformed them. Brushless motors are more efficient and generate less heat, and lithium-ion cells pack more energy into a smaller, lighter package. A modern 18V or 20V drill can match the power of many corded drills for most drilling and driving tasks. The convenience of no cord, no extension lead, and no outlet nearby is a huge advantage for working on ladders, in attics, or outdoors.

When Cordless Is the Clear Winner

For most DIYers and many professionals, cordless is the default choice. Here are the situations where cordless tools are clearly better:

• Portability and access: Working in tight spaces, on roofs, or in yards with no power source.
• Quick tasks: Driving a few screws, drilling a hole, or cutting a single piece – the time saved not dealing with cords is significant.
• Safety: No tripping hazard, no risk of cutting a cord, and no need for a GFCI-protected outlet in damp areas.
• Battery platform: Once you own two or three batteries and a charger, additional bare tools are relatively affordable.

For example, a cordless impact driver is the go-to tool for assembling furniture, hanging shelves, or any repetitive screw-driving. A cordless reciprocating saw is invaluable for pruning trees or demolition work far from an outlet.

When Corded Tools Still Make Sense

Corded tools are not obsolete. They remain the better choice for jobs that demand sustained high power or continuous operation. Consider these scenarios:

• Heavy cutting and grinding: A circular saw cutting thick hardwood, a miter saw making dozens of cuts, or an angle grinder on metal will drain batteries quickly. A corded tool delivers consistent power indefinitely.
• Stationary tools: Table saws, drill presses, and bench grinders are always used near an outlet, so a cord is no inconvenience.
• All-day professional use: Carpenters and contractors doing production work often prefer corded tools because they never need to stop and swap batteries.
• Cost and simplicity: Corded tools are generally cheaper, lighter, and have no battery degradation over time. If you only need a tool occasionally, a corded one can be a budget-friendly choice.

A corded angle grinder, for instance, can run for hours without losing power, while a cordless one would need multiple batteries and still might not match the torque under continuous load.

How to Choose Between Cordless and Corded

Before you buy, ask yourself these questions:

1. How often will you use it? If it’s once a month for a few minutes, corded is cheaper and always ready.
2. Where will you use it? If you’re always near an outlet, corded is fine. If not, cordless is worth the extra cost.
3. How long do you need it to run? For continuous heavy use, corded wins. For short bursts, cordless is fine.
4. Do you already own a battery platform? If yes, buying a bare cordless tool is often cheaper than a new corded tool.
5. What’s the power requirement? Check the tool’s wattage or amperage. A 15-amp corded circular saw will outperform most cordless saws in continuous cutting.

For most homeowners, a cordless drill/driver and impact driver are essential, and a corded circular saw or angle grinder covers heavy jobs. Many professionals own both – cordless for speed and convenience, corded for the jobs that demand endurance.

Common Problems and Misconceptions

One common misconception is that cordless tools are always weaker. That’s false for most drilling, driving, and even cutting tasks. The real limitation is runtime and sustained power. Another issue is battery degradation: lithium-ion batteries lose capacity over time and with heat. Storing them in a hot garage or leaving them on the charger can shorten their life. Also, not all batteries are equal – a 2Ah battery has half the capacity of a 4Ah, but may be lighter and more convenient for short tasks.

Another problem is the cost of additional batteries. A bare tool might be cheap, but a second battery and fast charger can cost almost as much as the tool. Factor that into your budget.

Cost Comparison

Corded tools are typically 20-40% cheaper than their cordless equivalents. For example, a corded circular saw might cost $60-100, while a cordless version (without battery) might be $100-150, and with a battery and charger, $200-300. However, if you already own batteries, the bare tool price is closer. Over time, batteries will need replacement (every 2-5 years depending on use), adding to the long-term cost of cordless. But the convenience and time saved often justify the premium for many users.

Safety Considerations

Both types have safety considerations. Corded tools require a grounded outlet and a GFCI for outdoor use. Never use a damaged cord. Cordless tools eliminate cord hazards but introduce battery risks: do not puncture, crush, or expose batteries to high heat. Use only the manufacturer’s charger. Always remove the battery when changing accessories or storing the tool. For both, wear appropriate eye and ear protection, and follow the tool’s instructions.

Frequently Asked Questions

Are cordless tools as powerful as corded tools?

For most tasks, yes. Modern brushless motors and higher voltage batteries (18V, 20V, 36V) provide comparable torque and speed for drilling, driving, and cutting. However, under sustained heavy load, corded tools maintain their power output while cordless tools may slow down as the battery voltage drops.

How long do cordless tool batteries last?

Runtime depends on the battery capacity (Ah) and the tool’s power draw. A 2Ah battery might last 20-30 minutes of light drilling, but only 5-10 minutes of heavy sawing. You can estimate with the calculator above. Battery lifespan (years) depends on charge cycles – typically 300-500 cycles before capacity drops significantly.

Can I use a cordless tool while it’s charging?

No, you cannot use the tool while the battery is in the charger. You need a spare battery to swap out. Some systems offer a backpack battery or a corded adapter, but these are rare and expensive.

Is it worth buying cordless tools if I already have corded ones?

If you frequently work in places without power or find cords annoying, yes. But if you’re happy with your corded tools and always work near an outlet, there’s no need to switch. Many people gradually replace their most-used tools with cordless and keep corded for heavy-duty or stationary use.

What does “20V max” mean on a cordless tool?

It’s a marketing term. The battery is actually 18V nominal (average voltage), but it reaches 20V at full charge. It’s the same as 18V from other brands. The voltage determines the tool’s potential power – higher voltage (36V, 54V) generally means more power for heavy tools.

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in t | Work time per day | hours | 2 | 0 | 24
in p | Tool power draw | watts | 500 | 100 | 3000
in b | Battery capacity | Wh | 108 | 20 | 2000
out r | Runtime per battery | hours | b / p | 2
out n | Batteries needed per day | - | t / (b / p) | 1