Ft-lbs to Nm Converter

What is a foot-pound? What is a newton-meter?

Both measure torque — twisting force. A foot-pound is one pound of force pushing on a lever one foot from the center of rotation. Lean on a one-foot wrench handle with 50 pounds of body weight and the bolt sees 50 foot-pounds. Swap to a two-foot breaker bar and the same 50 pounds of push delivers 100 foot-pounds, which is the whole reason a longer bar cracks a seized nut loose.

A newton-meter is the same idea in SI units: one newton of force, one meter out. A newton is small — roughly the weight of a medium apple in your hand — so a newton-meter is a much smaller helping of torque than a foot-pound. It takes 1.3558179483314 of them to equal one foot-pound.

Which unit you meet depends on who built the thing you're working on. US-built equipment, the US aftermarket, and most torque wrenches sold in the US are marked in foot-pounds. European and Japanese manufacturers publish in newton-meters, as does any manual written to an international standard. Neither unit is more correct. They describe the identical physical quantity, and the mismatch is why a converter tends to stay open on the bench: a typical passenger-car lug nut at 80 ft-lb is 108.4654 N·m, and a spark plug at 18 ft-lb is 24.4047 N·m.

One naming trap before the math. Foot-pounds get printed as ft-lb, lb-ft, lbf·ft, and "pound-feet" — torque is force times distance and multiplication doesn't care which order you write it, so all four mean the same unit. But lb-in is inch-pounds: one character away in print, twelve times smaller in reality.

How ft-lbs to Nm conversion works

One multiplication. No lookup table, no temperature-style offset, no direction to worry about.

That constant is exact, not a measurement someone rounded. It falls out of two definitions multiplied together. A pound-force is the weight of exactly 0.45359237 kg under standard gravity of exactly 9.80665 m/s², which is exactly 4.4482216152605 newtons. A foot is exactly 0.3048 meters. Torque is force times distance, so one pound-force acting one foot from the pivot is 4.4482216152605 × 0.3048 = 1.3558179483314 newton-meters. Nothing in that chain is approximate.

Here's the worked example the tool gives you. Type 50 in the box and the answer card reads 67.7909 N·m, with the calculation spelled out underneath — 50 ft-lb × 1.3558179483314 = 67.7909 N·m — and a second line telling you the same torque is 600 in-lb. Nothing to press. The number updates as you type, and both the result and the formula line have their own copy button so you can paste the figure into a work order or the whole calculation into a note to yourself.

It's one multiplication by one constant, which makes it strange how hard the rest of the web works to charge for it. The same conversion turns up three clicks deep inside a platform with a per-seat price, or behind a fourteen-day trial that wants a card number first, or bundled into a subscription somebody's employer already pays for and nobody can cancel. A unit conversion is not a product. This page is just the conversion.

For mental math, 1.36 is plenty. It runs 0.31% high, so a 100 ft-lb spec comes out 136 instead of 135.58 — four tenths of a newton-meter, comfortably inside the ±4% a click-type wrench is rated for. Use the shortcut to sanity-check a number, use the real constant when you're writing the spec down.

Common ft-lbs to Nm conversions

These are the figures the converter returns, at the values people actually look up. The third column is inch-pounds, because torque specs below roughly 20 ft-lb usually get published in in-lb instead and you'll want all three numbers on the page at once.

A few patterns worth keeping in your head. The relationship is linear, so it scales freely: if you remember that 100 ft-lb is 135.58 N·m, then 200 is 271.16 and 50 is 67.79, no calculator needed. Newton-meter figures are always the bigger number, by about a third — if your answer came out smaller than the foot-pound value you typed, you ran the conversion backwards.

The 20 ft-lb row is the one to notice. That's roughly where manuals stop publishing foot-pounds and switch to inch-pounds, and it's exactly where the two unit names start getting mixed on the same page of the same document. The typical figures in the last column are ballpark, not gospel — they're there to tell you whether your number is in a sane neighbourhood, not to replace the spec in your manual.

When you'll need to convert foot-pounds to newton-meters

The most common version: the manual and the wrench disagree. A car designed in Europe or Japan lists every fastener in N·m, and the click wrench in your drawer is stamped in ft-lb — or the exact reverse, on a US-built truck being serviced with a metric set bought online. The vehicle doesn't care which unit you think in, but you have to convert before you set the wrench.

Bicycle work runs into it constantly. Component makers publish in N·m, usually in small numbers (5 N·m on a stem bolt, 40 N·m on a cassette lockring), while plenty of shop torque wrenches read in inch-pounds or foot-pounds. Get it wrong on a carbon seatpost and you don't get a second try.

Then there's paperwork. Writing a service procedure, a quote, a parts listing, or a spec sheet for someone in another country means publishing both figures, and anything you hand to a customer needs to be right the first time. Same for coursework and exams — a physics or engineering problem stated in foot-pounds and answered in SI is a conversion sandwiched between two real calculations.

And sometimes you're just reading. Engine torque figures in a magazine or a spec page get quoted in lb-ft in the US and N·m everywhere else, and converting is the only way to tell whether two numbers you're comparing are actually different.

Edge cases and gotchas

lb-in is not lb-ft

This is the one that costs money. A spec written 89 lb-in pulled to 89 lb-ft is twelve times too tight — on a valve cover bolt or an aluminium thread, that means a snapped fastener or a stripped hole, and the tool that follows is an extractor. The converter refuses to help you make that mistake: type 89 in-lb and instead of an answer you get told it's inch-pounds, twelve times apart, divide by 12 first. Same for a newton-meter value typed into the foot-pound box — it names the converter that runs that direction rather than silently handing back a figure that's off by a factor of 1.36, in the wrong direction.

Precision, and how much of it is real

The converter shows four decimals above 1 N·m and six below it, which is more than any wrench can act on. That's deliberate — it rounds nothing for you, so you can round where it suits the job. In practice: set a wrench to the nearest whole newton-meter, write a spec sheet to one decimal, and only keep the long tail if you're carrying the figure into another calculation. A 0.0001 N·m difference has never mattered to a bolt.

Commas, minus signs, and typed units

You can paste the unit along with the number — 50 ft-lb, 50 lb-ft, and 50 foot pounds all read as 50. Grouped thousands work too, and if what you type looks ambiguous the tool says how it read it: enter 1,250 and you get 1,694.7724 N·m plus a note reading "Read as 1,250. If you meant 1.25, type it with a dot." A leading minus is rejected rather than accepted, because torque on a spec sheet is a size, not a direction, and a minus sign there is a typo.

Torque is a proxy for the thing you actually want

What holds a joint together is clamping load — the tension stretched into the bolt. Torque is just the easiest part of that to measure from outside, and most of what you apply is spent fighting friction under the head and in the threads. So anything that changes friction changes the result: a lubricated thread can reach 20–30% more clamping load at the same reading. Treat a spec as dry unless the manual says otherwise, and if it gives a lubricated figure, use that one.

Related converters

Going the other direction, the Nm to Ft-lbs converter takes newton-meters and returns foot-pounds. This page stays one-way on purpose — a single box that never has to ask which unit you just typed is faster than a mode switch, and it's why a mistyped N·m value can be caught and named instead of quietly converted.

For the small stuff, the Inch-Pounds to Foot-Pounds converter handles the twelve-times step, and if you're working through the physics rather than the spec sheet, the force calculator and the length converter cover the two halves torque is built from. Engine figures often arrive paired with power, which is what the horsepower calculator is for, and metric weight specs on the same page usually mean a trip through kg to lbs.

All of them work the same way: open the page, type, leave. No account, no email box before the answer, nothing stored — and 10% of every dollar Microapp earns goes to charity, off the top, audited quarterly.

Frequently asked questions

Is the foot-pound in a torque spec the same foot-pound used for energy?

Same size, different quantity. A foot-pound of work — force times the distance it moves — is 1.3558179483314 joules, the identical number you'd use for torque. But torque and energy aren't interchangeable ideas, and the SI names keep them apart: torque is written N·m, energy is written J, even though a joule is a newton-meter dimensionally. If you're tightening a bolt, you want N·m. If you're calculating work or energy, you want joules.

How many decimals should I actually keep?

For setting a wrench, round to the nearest whole newton-meter: 80 ft-lb is 108.4654 N·m, so set 108 and stop thinking about it. Click-type wrenches are typically rated around ±4%, which at that figure is more than four newton-meters of tolerance — far wider than anything you'd gain from a decimal place. Keep one decimal for a written spec, and the full figure only if the number feeds another calculation.

Can I convert a torque range, like 65–80 ft-lb?

Convert each end separately and keep it as a range. 65–80 ft-lb becomes 88.1282–108.4654 N·m, which you'd write as 88–108 N·m. Aim for the middle if the manual doesn't say otherwise, and don't round the ends outward — rounding 88.1 down to 85 to get a friendlier number puts you below the spec.

Can I type the unit, or numbers with commas?

Yes to both. 50, 50 ft-lb, 50 lb-ft, 50 lbf·ft, and 50 foot pounds all give 67.7909 N·m, and 1,000 reads as one thousand. Decimals need a dot rather than a comma — type 17.5, not 17,5, and if you use a comma you'll get told so instead of getting a wrong answer. What the box won't do is guess at a unit that isn't foot-pounds.

My spec says "torque to 80 N·m, then 90 degrees." What do I convert?

Only the 80. That's a torque-plus-angle spec, common on stretch bolts and cylinder heads: you set the initial torque, then turn a further measured angle. Degrees are degrees in both systems, so 90° stays 90°. 80 N·m is 59 ft-lb going the other way — and note that torque-to-yield fasteners specced this way are usually single-use, so check whether yours needs replacing before it goes back in.

Why does the answer show inch-pounds I didn't ask for?

Because spec sheets mix the two and you'll probably need it. Anything under roughly 20 ft-lb tends to get published in in-lb — it's a cleaner number on a cleaner scale — so a page listing suspension bolts in ft-lb will often list the covers and brackets in in-lb on the same table. Having all three figures at once is what stops you reading across the wrong column. It's a line under the answer, not a second mode, so the tool still does one job.

Where should I get the spec number in the first place?

From the manual for your exact model, every time — and if you're between sources, that's the thing worth chasing before you pick up a wrench. The typical figures on this page and in the table under the converter are there to tell you whether a number is in the right neighbourhood, not to stand in for the real one. Torque specs vary by bolt grade, thread, material, and whether the joint is dry or lubricated, and the difference between "about right" and right is the difference between a bolt that holds and one you get to drill out.