Torque specs matter. Whether you're tightening spark plugs, torquing lug nuts, or adjusting a bicycle stem, the difference between inch-pounds and foot-pounds can mean the difference between a secure connection and a stripped bolt. This calculator converts in both directions — enter inch-pounds to get foot-pounds, or enter foot-pounds to get inch-pounds.
Whether your repair manual lists specs in lb-ft while your torque wrench reads in lb-in, or you're translating specs from one format to another mid-job, this tool handles both conversions instantly. No mental math, no rounding errors — just the accurate equivalent you need to get it right.
What Are Inch-Pounds and Foot-Pounds?
Both inch-pounds (lb-in) and foot-pounds (lb-ft) measure torque — the rotational force applied when tightening a fastener or turning a wrench. The only difference is scale.
Inch-pounds (lb-in) are used for smaller fasteners and precision work: spark plugs, valve cover bolts, intake manifold bolts, bicycle components, and small engine parts. When a spec falls below about 10 lb-ft, it's often expressed in lb-in to avoid awkward decimals like 0.75 lb-ft.
Foot-pounds (lb-ft) are used for larger, more demanding connections: lug nuts, cylinder head bolts, axle nuts, and suspension hardware. Most standard automotive service manuals default to lb-ft for anything over a certain threshold.
Your service manual, torque chart, or spec sheet might use either unit — sometimes both within the same document. Knowing how to switch between them quickly keeps your work accurate.
The Conversion Formula
The math is based on one simple fact: there are 12 inches in a foot.
Inch-pounds to foot-pounds:
lb-ft = lb-in ÷ 12
Foot-pounds to inch-pounds:
lb-in = lb-ft × 12
So 120 lb-in equals exactly 10 lb-ft. And 25 lb-ft equals 300 lb-in. Simple enough to do mentally when the numbers are clean — but when you're working from a spec like 170 lb-in or 14.17 lb-ft, the calculator removes any chance of a rounding error.
How to Use This Calculator
- To convert inch-pounds → foot-pounds: Type your lb-in value in the top field. The foot-pound equivalent appears instantly on the right.
- To convert foot-pounds → inch-pounds: Type your lb-ft value in the bottom field. The inch-pound equivalent appears instantly.
- Both conversions update in real time — no button to press, no form to submit.
You can enter a value in either field and the other result updates automatically.
Common Torque Specifications
Knowing the conversion is useful, but knowing the range that actually shows up in real work is even better. Here's how torque specs typically land across common applications:
Application | lb-ft equivalent | lb-in equivalent |
|---|---|---|
Spark plugs (aluminum heads) | 10–20 lb-ft | 120–240 lb-in |
Spark plugs (cast iron heads) | 20–30 lb-ft | 240–360 lb-in |
Valve cover bolts | 5–6.7 lb-ft | 60–80 lb-in |
Intake manifold bolts | 15–25 lb-ft | 180–300 lb-in |
Oil drain plug | 20–30 lb-ft | 240–360 lb-in |
Bicycle stem bolts | 4–6 lb-ft | 48–72 lb-in |
Lug nuts (passenger car) | 80–100 lb-ft | 960–1,200 lb-in |
Small engine blade bolt | 11.7–14.2 lb-ft | 140–170 lb-in |
Always verify the exact specification for your vehicle or component using the manufacturer's documentation. These are general reference ranges only.
Practical Examples
Tightening spark plugs with the wrong wrench Your car manual specifies 18 lb-ft for spark plug torque, but your small torque wrench only reads in lb-in. Convert: 18 × 12 = 216 lb-in. Set your wrench to 216 lb-in and you're exactly on spec — no guessing.
Bicycle stem bolt precision Your bike's stem spec is 44 lb-in, and a friend asks if "about 4 foot-pounds" is close enough. Enter 44 lb-in → 3.67 lb-ft. That's nearly 9% below 4 lb-ft, which on a carbon fiber stem could mean the difference between secure and slipping. Worth being precise.
Lawnmower blade bolt The service manual says blade bolts should be torqued to 170 lb-in. Your click-type torque wrench reads lb-ft. Enter 170 lb-in → 14.17 lb-ft. Set your wrench to 14.17 — rounding to 14 would leave you about 2 lb-in short on a safety-critical fastener.
Reading an ATV service manual Your ATV manual lists a particular bolt at 200 lb-in. A forum post says to torque it "to about 16-17 foot-pounds." Enter 200 lb-in → 16.67 lb-ft. The forum advice is accurate — but now you have the exact figure, not an approximation.
Valve cover on a small engine Spec calls for 7.5 lb-ft. Your beam torque wrench reads lb-in. Enter 7.5 lb-ft → 90 lb-in. Set the wrench to 90 and apply even pressure — done.
When to Use Inch-Pounds vs. Foot-Pounds
The unit choice isn't random. Each one fits a practical range:
Inch-pounds make sense when:
- Torque values would be a fraction in lb-ft (anything under about 8 lb-ft is often listed in lb-in)
- Working with precision components: sensors, electronics, small engine hardware
- Using a small torque screwdriver or a low-range torque wrench (typically 0–250 lb-in)
- Following bicycle, motorcycle, or small engine manufacturer specs
Foot-pounds make sense when:
- Torque is in the double digits or higher
- Working with automotive drivetrain, suspension, or wheel hardware
- Using a standard 1/2" drive torque wrench (typically 25–250 lb-ft)
- Following most US automotive service manual specs (lb-ft is the default for most car work)
The good news: you don't need to memorize which unit a spec will use. Keep this converter handy and you'll always have both in seconds.
Technical Notes
Conversion factor: 1 lb-ft = 12 lb-in (exact, by definition)
- lb-in → lb-ft: divide by 12
- lb-ft → lb-in: multiply by 12
There is no approximation in the conversion itself — the relationship between inch and foot is exact. Decimal results appear due to the value entered, not the formula.
Unit notation: lb-in, in-lb, and in·lb are all inch-pounds. lb-ft, ft-lb, and ft·lb are all foot-pounds. The notation varies by publication style but the values are identical.