RIR / RPE Conversion Calculator
Converts between RIR (Reps in Reserve) and RPE (Rate of Perceived Exertion) for strength training.
—
RIR and RPE: autoregulation in strength training
RPE (Rate of Perceived Exertion) is a 1–10 scale adapted by Mike Tuchscherer (Reactive Training Systems) from the original Borg scale to quantify effort in resistance training. RIR (Reps in Reserve) is the direct complement: how many reps remain in the tank before failure. The conversion is linear: RPE = 10 − RIR, so RPE 10 = 0 RIR (technical failure), RPE 9 = 1 RIR, RPE 8 = 2 RIR, RPE 7 = 3 RIR, and so on.
Helms et al. (2016, Strength & Conditioning Journal) validated the RIR-based RPE scale and showed strong correlation with bar velocity loss in compound lifts. It is the autoregulation tool of choice in modern powerlifting because it lets you adjust load by day-to-day fatigue: instead of a fixed %1RM, you target an RPE (e.g. “3x5 @ RPE 8”) and pick the load that puts you at that effort. This sustains volume on bad days and allows progress on good ones.
Applications
Powerlifting and weightlifting programming, daily-load autoregulation, %1RM-equivalence estimation via Tuchscherer's RPE chart, peaking plans before competition, and intensity gauges in hypertrophy programs (typical hypertrophy block: RPE 7–9; strength block: RPE 8–10).
FAQ
Are RPE and RIR the same thing? They are inverse complements. RIR counts what is left, RPE measures effort already produced. The relation is fixed: RPE + RIR = 10.
Is RPE accurate for beginners? Less so. Studies show beginners systematically underestimate RPE (think they are at 8 when they are at 6). Accuracy improves with 6–12 months of training near failure.
What is half-RPE (8.5)? Used to gauge intermediate effort, e.g. RPE 8.5 = 1–2 RIR, very common in Tuchscherer-style programming. Allows finer load progression.
Related Tools
V-Bending Force
Calculate the force to bend a sheet in a V-die, F = (C·σ_r·L·t²) ÷ V, from the process constant C (~1.33 for free V-bending), the material tensile strength σ_r (N/mm²), the bend length L (mm), the sheet thickness t (mm) and the V-die opening V (mm). V-bending is the most common forming operation on press brakes: the sheet rests on a V-shaped die and a punch forces it in, bending it to the desired angle. Force grows with the SQUARE of thickness (thicker sheets need much higher forces) and with material strength, and decreases with die opening (larger V → lower force, but larger bend radius). The rule of thumb uses V ≈ 6-8 times the thickness. Computing the force is essential to select the press brake (tonnage) and not overload the tooling. The bend-tonnage tables ubiquitous in sheet shops are exactly this formula applied to combinations of thickness, material and die opening. Enter the constant, tensile strength, length, thickness and die opening.
Gear Torque
Calculate the torque transmitted by a gear, T = (F_t·d) ÷ 2000, from the tangential force F_t (N) and the pitch diameter d (mm); the result is in N·m (the 2000 converts d/2 from mm to m). Torque is the moment the gear transmits about its axis, and the tangential force F_t acts at the pitch radius (d/2), creating that moment. This relation is the bridge between the POWER/torque side (what the shaft transmits) and the TOOTH-FORCE side (what sizes the strength): from shaft torque, the tooth tangential force (F_t = 2T/d) is obtained, which then feeds the bending (Lewis) and contact (Hertz) calculations. Conversely, given the tangential force, the torque is obtained. In a gear train, torque CHANGES at each stage by the gear ratio (a reduction that multiplies speed by 1/i multiplies torque by i, conserving power minus losses), while power stays roughly constant. So a reducer's last stage (low speed) transmits the HIGHEST torque and needs the most robust gears. Knowing the torque at each gear is essential to size teeth, shafts, keys and bearings. Enter the tangential force and the pitch diameter.
Borg Perceived Exertion Scale Calculator
Shows the Borg RPE scale (6-20) and maps it to approximate target heart rate based on age.
Rain Intensity in mm per Hour
Classifies rain intensity (light, moderate, heavy, very heavy) from precipitation rate in millimeters per hour.
Blank Holder Force
Calculate the blank holder force in deep drawing, F_s = p·(π/4)·(D² − d²), from the blank holder specific pressure p (N/mm²), the blank diameter D (mm) and the punch diameter d (mm). In drawing, besides the punch forming the cup, there is a BLANK HOLDER pressing the disc rim (the annular area between blank and punch) against the die, with a controlled force. Its role is CRITICAL: to prevent WRINKLE formation on the rim. As it draws, the rim material flows inward and, reducing its perimeter, tends to wrinkle (like crumpled fabric), because it is under circumferential compression. The blank holder grips the rim with enough pressure to prevent wrinkles, but NOT so much as to stop the material from flowing (which would tear the bottom). It is a delicate balance: too little pressure → wrinkles; too much → rupture. The specific pressure p is typically a small fraction of the material strength (0.5-3 N/mm² for steels), and the total force is that pressure times the annular area where the holder acts. Computing this force is essential in drawing-tool design and press setup (which applies the holder via springs, pneumatic or hydraulic cushions). Enter the specific pressure and the blank and punch diameters.
Reactor Conversion (Batch)
Compute a reactant's conversion, X = (C₀ − C)/C₀·100%, the fraction of reactant consumed in the reaction, from the initial (C₀) and final (C) concentrations. Conversion is the fundamental measure of a chemical reaction's progress: 0% means nothing reacted, 100% that the reactant is exhausted. Together with selectivity and yield, it defines a reactor's performance. Enter the initial and final concentrations.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.