From One-Rep Max to Training Block: Percentages, RPE and Loads You Can Actually Build

Getting an estimated one-rep max is the easy part. You type a weight and a rep count into a calculator and it hands back a number like 152.5 kg. Then Monday comes, the program says “4 × 5 at 80%”, and you’re standing at the rack doing arithmetic. Is 80% of 152.5 a weight you can load? Should it feel easy or hard? What do you put on the bar next week? A good block depends far more on those small decisions than on the estimate itself.

This post covers the step after the estimate. The formulas, and why Epley and Brzycki disagree, are covered in how to calculate your one-rep max. The loading arithmetic of subtracting the bar and halving is covered in barbell plate math. Here we take one lifter’s squat through a four-week block and look at what goes wrong at each stage.

Estimate from a set you could have repeated

Every 1RM formula assumes the rep set you enter was taken to failure, or very close. Most people don’t train that way. They stop a set with a rep or two left, which is the sensible thing to do, and then enter it as if it were a max effort. That gives a low estimate. A low estimate isn’t dangerous, but it makes the block feel strangely easy and wastes a few weeks.

The fix is to count the reps you left behind. Our lifter squatted 132.5 kg for 4 reps and was confident there was one more in the tank. Entered as 132.5 × 4, the One Rep Max Calculator averages its five formulas to about 148.4 kg. Entered as 132.5 × 5 (four done, one in reserve), it gives about 152.6 kg, which the tool shows as 152.5 kg with its default 2.5 kg rounding. That 4 kg gap runs through every percentage in the block.

Some cautions on doing this honestly:

• Only add reps you were sure of. Most lifters judge “one more” fairly well on heavy sets of three to six and badly on sets of twelve. If you aren’t sure, enter the reps you actually did.
• Stay in the 3–8 rep range for the input. The calculator accepts up to 15 reps, but the hint under its reps field says estimates are best within 1–10 and less accurate above 12. The earlier post explains why.
• The lift selector is a label. The tool runs the same five formulas whether you pick squat, bench or deadlift. It won’t correct for the fact that many people get more reps at a given percentage on a squat than on a bench press.

Some programs go one step further and train from a training max, usually 90% of the estimate (Jim Wendler’s 5/3/1 popularised this). For our lifter that is 152.5 × 0.90 = 137.25, or 137.5 kg. If you’re coming back from a layoff, or your estimate came from a single set on a good day, a training max is cheap insurance. For the rest of this example we’ll use the full 152.5 kg and let RPE (below) catch any error.

Percentages set the load, RPE checks the day

Percentages and RPE do different jobs. A percentage is decided in advance from a number that may be weeks old. RPE (rating of perceived exertion) on the reps-in-reserve scale describes how the set felt today. Using both lets the plan hold its shape while you keep an eye on how training is actually going.

The scale most lifters now use ties RPE to reps in reserve (RIR):

RPE	Reps in reserve	What it means
10	0	Nothing left. Another rep would fail
9	1	One more rep, definitely
8	2	Two more
7	3	Three more, bar speed still good
6 or below	4+	Warm-up territory. Hard to judge precisely

You can connect the two with the rep column in the calculator’s %1RM table. The table pairs each percentage with a typical number of reps to failure. At 80% it lists 7–8 reps, so a set of 5 at 80% should leave about 2–3 in reserve, which is RPE 7–8. At 85% it lists 5–6, so a set of 4 there is roughly RPE 8–9. These are population averages, not promises. Here is the block built from that table, using the tool’s 152.5 kg estimate:

Week	Prescription	% of 1RM	Calculator load (2.5 kg rounding)	Expected RPE
1	4 × 6	75%	115 kg	6–7
2	4 × 5	80%	122.5 kg	7–8
3	3 × 4	85%	130 kg	8–9
4 (deload)	3 × 5	65%	100 kg	5 or below

The RPE column is for checking, not decoration. If week 1’s sets of 6 at 115 kg feel like RPE 9, your estimate is too high. Maybe the “one more rep” wasn’t really there. Drop the rest of the block by 5% rather than grinding through it. If week 3 feels like RPE 6, the estimate was low, and you’ve learned something useful for the next block. Expect the last set of a group to feel a point or so harder than the first. Fatigue builds across sets, and the table describes a fresh first set.

Round to the plates you own, not the ones the chart assumes

The calculator rounds both the 1RM and every row of the percentage table to a step you choose: 2.5 kg, 5 lb or no rounding at all. It works the percentages from the unrounded estimate, so 80% of 152.56 kg is 122.05 kg, which rounds to 122.5. The 2.5 kg default makes sense for a commercial kg gym, where 1.25 kg plates are the smallest you’ll usually find. If you own fractional plates, it’s too coarse.

With rounding turned off, the same block reads 114.4, 122.0, 129.7 and 99.2 kg. The Barbell Plate Loading Calculator includes 0.5 kg and 0.25 kg plates in its kg list, so with those switched on it can build 114.5, 122, 129.5 and 99 kg exactly. That puts each week within about half a kilo of the plan instead of up to 1.25 kg. On a squat, that difference rarely matters. On an overhead press it can. A 2.5 kg jump on a 50 kg press is a 5% step, and the same jump on a 180 kg deadlift is about 1.4%. Light lifts are where micro-plates matter.

Check two things in the plate calculator before you rely on it:

1. It treats each plate size as on or off, not as a count. If 0.5 kg plates are enabled, it assumes you have as many as the answer needs. For 129.5 kg on a 20 kg bar, the per-side load is 54.75 kg. It comes out as 25 + 25 + 2.5 + 1.25 + 0.5 + 0.5, which is two 0.5 kg plates per side. If you own only one pair, that load isn’t really available. Use 129 or 130 kg instead.
2. It never rounds up. When it can’t hit a target exactly, it loads a weight below the target and tells you how many kilos or pounds short you are. That’s the safer direction for a working set.

Training in a pound gym

Change the unit in the 1RM calculator from kg to lb and the tool converts your entered weight (132.5 kg becomes 292.1 lb) and moves the rounding step to 5 lb. It then gives an estimate of about 336 lb, displayed as 335. Do all of the block’s percentages in the gym’s own unit from there. Calculating in kilograms and converting each load one by one gives you odd numbers like 270.1 lb that no plate set can build.

The pound side of the plate calculator has a coarser floor. Its lb list stops at 2.5 lb plates, so the smallest change it can make is 5 lb total. Week 1’s 75% works out to 252.25 lb, and with the lb plates in the tool you can load 250 or 255 lb but not 252.5. Fractional plates of 1.25 lb and smaller do exist, but the tool doesn’t list them. If you own them, work out the extra per side yourself and add them to what the calculator gives you.

Week	%	kg gym, 0.25 kg plates	lb gym, 2.5 lb smallest plate
1	75%	114.5 kg	250 lb
2	80%	122 kg	270 lb
3	85%	129.5 kg	285 lb
4	65%	99 kg	220 lb

For week 3, 285 lb on a 45 lb bar is 120 lb per side: 45 + 45 + 25 + 5. That’s four plates and quick to load.

Move the estimate between blocks, not inside them

Within a block, the percentages stay put and RPE does the adjusting. Between blocks, you re-estimate. The cleanest input is the hardest work set of week 3, because it’s recent, heavy and low-rep.

Suppose our lifter’s last set of 4 at 130 kg felt like RPE 7. That’s three reps in reserve, so the input is 130 × 7. The calculator now gives about 157.6 kg (157.5 rounded), up 5 kg from the start. One block of good sets doesn’t prove a 5 kg gain, though, and a jump that big at the top of the next block is how people stall in week 3. A sensible cap is to raise the estimate by no more than about 2.5 kg for bench and overhead press and 5 kg for squat and deadlift per block, whatever the calculator suggests. Wendler’s 5 lb and 10 lb training-max increments follow the same idea. Here the cap and the estimate agree, so the next block starts from 157.5 kg.

What if week 3 went badly, with sets of 4 at 130 kg grinding out at RPE 9.5? Don’t lower the estimate on one bad day. Run the same block again. If it happens twice, take 5% off.

Bodyweight changes over a block also make raw numbers misleading. A lifter who adds 5 kg to their squat while gaining 4 kg of bodyweight has made a different kind of progress from one who adds 5 kg at a steady weight. The Wilks, DOTS & IPF GL calculator puts both on one scale. Log a DOTS score at the start and end of each block, using the same estimated maxes, and you can tell real strength gains from weight gain. The Wilks, DOTS and IPF GL guide explains which coefficient to use.

Safety

Estimated maxes and RPE are planning tools. They can’t tell you whether a given heavy set is safe for you on a given day. Work near your limit with safety arms set or a spotter, stop a set when your form breaks down rather than when you reach the target number, and if you have an injury or a medical condition, get advice from a qualified coach or clinician. This is general information, not professional advice.

Running the block with the tools

Start with your best recent set in the One Rep Max Calculator, counting any reps you were sure you had left. Read each week’s load from its percentage table. Before you write those numbers into your log, check them against the plates you own in the Barbell Plate Loading Calculator. If your bodyweight is changing, a DOTS score at each end of the block shows whether the block made you stronger.