What is tonne-force (tf)?
Tonne-force is a unit of force based on weight. It equals the force from gravity on a 1-metric-ton mass under standard gravity. You may also see it written as metric ton-force.
What is a poundal (pdl)?
A poundal is a unit of force from the foot-pound-second (FPS) system. It’s defined as the force needed to speed up a 1-pound mass by 1 foot per second squared.
How many poundals are in 1 tonne-force?
1 tonne-force equals about 70,931.6 poundals.
What’s the formula to convert tonne-force to poundals?
Use this direct conversion:
This uses standard gravity and standard unit definitions.
How do you convert poundals to tonne-force?
Use the reverse conversion:
Is tonne-force the same as a “ton-force”?
Not always. Tonne-force is based on the metric tonne (1,000 kg).
“Ton-force” can mean force based on a short ton (2,000 lb) or a long ton (2,240 lb), depending on the context. The values will not match.
Why does standard gravity matter in tf to pdl conversions?
Tonne-force is tied to standard gravity (g₀ = 9.80665 m/s²). That fixed value sets:
- 1 tf = 9,806.65 newtons (N)
Once tf is in newtons, it converts cleanly to poundals.
How do tonne-force and poundals relate to newtons?
They convert through newtons:
- 1 tf = 9,806.65 N
- 1 pdl ≈ 0.138255 N
So:
- 1 tf ≈ 9,806.65 ÷ 0.138255 ≈ 70,931.6 pdl
Can you show a quick example conversion?
Yes. Multiply by 70,931.6:
- 2 tf ≈ 2 × 70,931.6 = 141,863.2 pdl
- 0.5 tf ≈ 0.5 × 70,931.6 = 35,465.8 pdl
How should you round tf to pdl results?
Rounding depends on your use. For many loads and force checks, rounding to the nearest whole poundal is fine. For lab work or detailed math, keep more digits (at least 1 decimal place, often more).
Are tonne-force and poundal SI units?
No. The newton (N) is the SI unit of force.
Tonne-force is a gravity-based unit, and the poundal is an older FPS unit. You’ll still see both in some reference tables and older specs.
What symbols are used for tonne-force and poundal?
Common symbols are:
- tf for tonne-force (also seen as tonne-force or metric ton-force)
- pdl for poundal