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Time Under Tension Calculator

See your set’s total time under tension.

How it is calculated

Enter the seconds of each phase of one rep: eccentric E (lowering), pause at the bottom Pb, concentric C (lifting) and pause at the top Pt, plus the number of reps n. One rep lasts E + Pb + C + Pt seconds and the set's time under tension is TUT = (E + Pb + C + Pt) × n. Eccentric, concentric and reps are required; the two pauses are optional and count as 0 when left empty. The total is shown in whole seconds and the per-rep time with one decimal, and phases may be fractions of a second (1.5 is fine). Reps must be a whole number above zero, no phase can be negative, and a rep time of zero shows no result.

Worked example

A set uses a 4-1-2-1 tempo: 4 seconds down, 1 second pause at the bottom, 2 seconds up, 1 second hold at the top, for 8 reps. One rep: 4 + 1 + 2 + 1 = 8 seconds. The set: 8 × 8 = 64 seconds. The tool shows a time under tension of 64 s and 8.0 s per rep. Compare a plain 2-0-1-0 tempo for 8 reps: 3 s per rep and 24 s for the set, so the slow tempo almost triples the time the muscle is loaded.

Try this example →

Common mistakes

  • Counting the rest between sets. TUT covers only the reps themselves, so rest periods are left out.
  • Putting the whole tempo into one field. Each phase has its own box, so a 4-1-2-1 tempo means 4, 1, 2 and 1 in four boxes, not 8 in one.
  • Leaving the eccentric or concentric box empty because that phase is quick. Both are required, so enter a real value such as 1 second.
  • Mixing up the order of the tempo digits. Most notations start with lowering, but some programs list the lift first, so check which phase your program starts with.
  • Typing a fractional rep count such as 8.5, or a negative phase. The tool shows no result for these.

About this calculator

Time under tension (TUT) is the total number of seconds a muscle spends actively working during a set, calculated by multiplying each rep’s tempo phases — eccentric (lowering), any pause, concentric (lifting), and any hold — by the number of reps performed. A tempo written as 4-1-2-0, for four seconds down, one second pause, two seconds up, no hold, applied over 10 reps gives 70 seconds of total time under tension.

Bodybuilders and hypertrophy-focused coaches manipulate TUT deliberately because muscle growth responds strongly to how long a muscle stays under mechanical load, not just how much weight moves — slowing the eccentric phase is a common way to increase stimulus without adding weight. Physical therapists use the same concept in the opposite direction, prescribing slow, controlled tempos during rehab to build strength safely under a lighter, more manageable load.

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