Inch-Pound to Watt Hour
in·lb
Wh
Conversion History
| Conversion | Reuse | Delete |
|---|---|---|
1 in·lb (Inch-Pound) → 0.00003138467472989353 Wh (Watt Hour) Just now |
Quick Reference Table (Inch-Pound to Watt Hour)
| Inch-Pound (in·lb) | Watt Hour (Wh) |
|---|---|
| 1 | 0.00003138467472989353 |
| 2 | 0.00006276934945978706 |
| 5 | 0.00015692337364946764 |
| 12 | 0.00037661609675872233 |
| 25 | 0.00078461686824733819 |
| 50 | 0.00156923373649467639 |
| 100 | 0.00313846747298935278 |
About Inch-Pound (in·lb)
The inch-pound (in·lb) is a unit of torque and small-scale energy used in US customary mechanical engineering, equal to approximately 0.11299 joules. It represents the work done by one pound-force over a distance of one inch, or equivalently, a torque of one pound-force acting at a radius of one inch. Small fastener torque specifications, precision instrument settings, and electronic component assembly instructions routinely use inch-pounds. It is 1/12 of a foot-pound.
A laptop hinge torque specification is often 2–5 in·lb. Small machine screws in electronics are typically torqued to 1–4 in·lb.
About Watt Hour (Wh)
A watt-hour (Wh) is the energy consumed or produced by a one-watt device operating for one hour, equal to 3,600 joules. It is widely used for small battery and energy storage capacities — smartphone batteries, power banks, and small electronic devices. A smartphone battery holds roughly 10–15 Wh; a laptop 50–100 Wh. The watt-hour is the stepping-stone unit between the joule (too small for practical appliance use) and the kilowatt-hour (the billing unit for mains electricity).
A phone charger running for an hour uses about 5–10 Wh. A 100 Wh portable power bank can charge a typical smartphone about seven times.
Inch-Pound – Frequently Asked Questions
Why are small fastener torque specs given in inch-pounds instead of foot-pounds?
Inch-pounds provide finer resolution for small fasteners where foot-pound values would be fractions (e.g., 3 in·lb vs 0.25 ft·lb). Electronics assembly, firearms scope mounting, and bicycle component installation all specify inch-pounds because over-torquing a small screw by even one foot-pound can strip threads or crack housings.
What happens when you over-torque a small fastener by just 2 inch-pounds?
On an M3 screw into aluminum (spec: 5 in·lb), exceeding by 2 in·lb — a 40% overload — can strip the threads or crack a thin boss. Small fasteners have almost no safety margin because the thread engagement area is tiny and the materials (plastic, aluminum, brass) are soft. This is why electronics repair shops use beam-type or preset click torque drivers accurate to ±0.5 in·lb, and why aerospace assembly procedures treat inch-pound specs as hard limits, not suggestions.
What torque in inch-pounds do laptop and electronics screws need?
Laptop hinge screws typically require 2–5 in·lb, hard drive mounting screws 2–4 in·lb, and motherboard standoff screws 5–8 in·lb. Going beyond the spec risks cracking plastic bosses or stripping soft aluminum threads. A precision bit driver with a torque limiter is essential for electronics repair work.
What is the difference between inch-pounds as torque and inch-pounds as energy?
Dimensionally they are identical — force times distance — but context differs. As torque, 1 in·lb means one pound-force applied at one inch from a pivot. As energy, it means one pound-force pushing through one inch of linear displacement (0.11299 J). In practice, inch-pounds almost always refer to torque in mechanical specifications.
Why do firearms manufacturers specify scope ring torque in inch-pounds?
Scope rings and bases use small screws that are easily damaged, and consistent clamping force is critical for zero retention under recoil. Typical specs are 15–25 in·lb for ring screws and 30–65 in·lb for base screws. Under-torquing lets the scope shift; over-torquing cracks the scope tube or strips the screw. A dedicated inch-pound torque wrench is considered essential kit for precision rifle setup.
Watt Hour – Frequently Asked Questions
Why are portable battery capacities listed in watt-hours instead of milliamp-hours?
Watt-hours account for both current and voltage, giving the true energy stored. A 10,000 mAh power bank at 3.7 V holds 37 Wh, but at 5 V output it delivers only about 7,400 mAh due to voltage conversion losses. Airlines use the Wh rating (max 100 Wh carry-on) because it reflects actual energy — and therefore actual fire risk — regardless of battery voltage.
How many watt-hours does a typical smartphone battery hold?
Most smartphones have batteries rated at 10–18 Wh. An iPhone 15 Pro holds about 12.7 Wh; a Samsung Galaxy S24 Ultra about 18.4 Wh. For context, fully charging an 18 Wh phone from a wall outlet costs less than 0.01 kWh — roughly one-tenth of a cent on a typical electricity bill.
What is the airline limit for lithium batteries in watt-hours?
Most airlines allow lithium-ion batteries up to 100 Wh in carry-on luggage without approval. Batteries between 100 and 160 Wh (e.g., large camera or drone batteries) require airline permission, and batteries above 160 Wh are banned from passenger flights. A standard laptop battery is 50–100 Wh; a large power tool battery can exceed 160 Wh.
Why did the electronics industry settle on watt-hours instead of joules for battery labels?
Watt-hours map directly to how consumers think about devices: a 50 Wh battery powering a 10 W laptop lasts about 5 hours — simple division. Expressing the same battery as 180,000 joules gives no intuitive sense of runtime. Airlines also adopted Wh for lithium battery safety limits (100 Wh carry-on threshold) because it communicates energy density risk in a unit engineers and passengers can both grasp.
How many watt-hours does it cost to charge a laptop?
A typical laptop battery holds 50–100 Wh, so a full charge from empty uses 50–100 Wh of energy (plus about 10–15% lost as heat in the charger). At average US electricity rates, that is roughly 1–2 cents per charge. Over a year of daily charging, a laptop costs about $4–$7 in electricity — far less than most people assume.