# RPE Calculator | Forge > **Quick Answer:** The Forge RPE Calculator pairs your estimated one-rep max with a target RPE and rep count to give you a working weight, using the Reactive Training Systems chart. Every target shows reps in reserve in plain language. Free and ungated, in lb and kg. Example: a 315 lb estimated max with a target of 5 reps at RPE 8 gives a 250 lb working weight. **dateModified:** 2026-08-09 --- ## Key Facts - **What it does:** Converts an estimated max, a rep count, and a target RPE into a working weight - **Chart:** Reactive Training Systems (RTS), reps 1 through 12 at RPE 6.5 to 10 - **RPE scale:** 6.5 to 10. RPE 10 is a maximal set, and each half point below 10 adds about half a rep of cushion. - **RIR translation:** Every RPE shows reps in reserve (RPE 8 = 2 reps in reserve) - **Rounding:** Weights round to the nearest 5 lb or 2.5 kg - **Units:** lb and kg - **Cost:** Free. No sign-up. --- ## How to Use It 1. Pick lb or kg. 2. Enter your estimated one-rep max. No estimate yet? Get one from any recent hard set with the 1RM calculator. 3. Pick your target reps. 4. Pick your target RPE. 5. Load the weight it gives you. The full chart below shows every rep count and effort level at once. --- ## How the Math Works Working weight equals your estimated 1RM times the percentage for the chosen reps and RPE, taken from the Reactive Training Systems chart, rounded to the nearest 5 lb or 2.5 kg. On the RTS chart, 5 reps at RPE 8 sits at 78.6% of your max, and 3 reps at RPE 9 sits at 89.2%. The chart assumes a typical strength curve on barbell compounds and loses precision past 12 reps and on isolation work. Reps-in-reserve ranges follow the usual convention where RPE 10 leaves zero reps and each half point down adds about half a rep of cushion. Most productive training lives between RPE 6.5 and 9. Living at RPE 10 burns recovery that the rest of your program needs. --- ## Frequently Asked Questions ### What does RPE stand for? Rate of perceived exertion. In lifting it runs from 6 to 10 and describes how close a set came to failure. RPE 10 is a maximal set. Each half point below 10 adds roughly half a rep you could have completed with good form. ### How do I judge my RPE during a set? Ask yourself one thing as you rack the bar: how many clean reps were left? With practice your answer gets accurate within about one rep. Filming your sets helps early on, because bar speed on the last rep gives the answer away. ### What is RIR and how does it relate to RPE? RIR means reps in reserve, the literal count of reps left in the tank. It is RPE flipped around: 2 RIR and RPE 8 describe the same set. Many lifters find counting reps up easier than rating effort down, so this calculator shows both for every target. ### Why does the calculator need my estimated 1RM? The RPE chart links effort and reps to a percentage of your max. Multiply your estimated max by that percentage and you get the weight that should land you at the target effort on a typical day. If you have no max estimate yet, our 1RM calculator will get you one from any recent hard set. ### Can beginners use RPE? Yes, with one adjustment. Newer lifters misjudge their reps in reserve by a rep or two, so an intended RPE 8 might come out closer to a 7. That error shrinks fast with practice. Keep targets at RPE 8 or below for your first couple of months and the worst outcome is a slightly easy set. ### Should every set go to RPE 10? Save maximal sets for rare tests. Most productive training lives between RPE 6.5 and 9, where the effort stays high enough to drive progress and low enough to repeat across a full week. Living at RPE 10 burns recovery that the rest of your program needs. --- ## Forge Sets the Weight For You Forge is an AI personal trainer for iOS and Android. It builds an adaptive plan, picks the weight and effort target for every set, and adjusts as you log your training. You get 4 trainer personalities, a 24/7 trainer chat, and workout logging in one place. Pricing: $19.99/month, $59.99/year, or $6.99/week. All plans include a 7-day free trial. - **App Store:** https://apps.apple.com/us/app/forge-ai-personal-trainer/id6758403402 - **Google Play:** https://play.google.com/store/apps/details?id=com.tendylabs.forge - **Website:** https://forgetrainer.ai --- *https://forgetrainer.ai/tools/rpe-calculator*