FitTopTraining on your own terms

Working weights calculator

Short answer: enter your 1RM in kilograms and a percentage (or a percentage range) — the calculator shows the exact weight and the working weight rounded to the nearest multiple of the chosen plate step. The calculation runs right in your browser and nothing is sent anywhere.

Worked example

1RM (median of the 1RM calculator for a 100 kg × 5 set), 80 % of 1RM → exact weight 116.5 kg working weight at a plate step of 93.2 kg Check by hand: 116.5 × 80 / 100 = 93.2; the nearest multiple of 2.5 is 92.5. 2.5 kg — 92.5 kg.

Calculate working weights

Units
For example 116.5. Accepted from 1 to 500 kg — you can take it from the 1RM calculator.
From 50 to 100, for example 80. Halves are fine — 72.5.
For the range table, for example 85. Rows step by 5 % and include the end point.
Plate step

How to use the calculator

  1. Take a one-rep max: measured — or estimated in the 1RM calculator.
  2. Enter it in kilograms — halves are allowed, for example 116.5.
  3. Enter a percentage of 1RM (from 50 to 100) — a single value or a range through the "from" and "to" fields.
  4. Choose the plate step your gym actually has: 1.25 / 2.5 / 5 kg.
  5. Press "Calculate".

The result is a table: percentage, exact weight and the working weight rounded to the chosen plate step. For a single percentage there is one row, for a range one row every 5 %.

Where the formula comes from and why rounding

Dosing a load as a percentage of 1RM is a standard way to prescribe strength training: it describes both light zones (for example 40–60 % for endurance work in the ACSM 2009 position stand) and heavier linear ranges. The exact weight is simply a multiplication: 1RM × percentage / 100.

But you cannot put 93.2 kg on a bar: plates are made in standard denominations — 1.25 / 2.5 / 5 kg and above. The calculator therefore rounds the exact weight to the nearest multiple of the chosen step. When the distance to two neighbouring multiples is equal, rounding goes up. Sometimes rounding moves the weight below the exact value, sometimes above — a deliberate compromise for being able to load real equipment.

How to check it by hand

Example: 1RM 116.5 kg (the median of the 1RM calculator for a 100 kg × 5 set), percentage 80 %, plate step 2.5 kg.

  1. Exact weight: 116.5 × 80 / 100 = 93.2 kg.
  2. Nearest multiples of 2.5: 92.5 and 95. Distances: 0.7 and 1.8 → 92.5 is closer.
  3. Working weight: 92.5 kg.

For comparison: with a 1.25 kg step the result would be 93.75 kg (93.2 / 1.25 = 74.56 → 75 × 1.25), and with a 5 kg step 95 kg (93.2 / 5 = 18.64 → 19 × 5).

Limitations

  • The working weight inherits the error of the source 1RM: an estimated maximum can differ from the real one by 10 % or more.
  • Rounding to a plate step deliberately shifts the weight; check which denominations are actually available in your gym.
  • The 50–100 % range covers linear strength and volume work but not every training scheme.
  • Working weights are a guide, not a prescribed load: adjust by how you feel and by technique.

Author

FitTop editorial team — Site editorial team

FitTop is an independent project. Editorial material is separated from advertising and partnership elements. The editorial team does not give individual medical advice; for health questions, see a doctor or a qualified specialist.

Sources and review date

  1. Progression Models in Resistance Training for Healthy Adults (ACSM Position Stand) — American College of Sports Medicine / Medicine & Science in Sports & Exercise, 2009-03-01. Supports: Dosing a load as a percentage of 1RM as a common way to prescribe strength training (for example light and moderate zones of 40–60 % 1RM for endurance, and unloading zones up to 60 % 1RM for explosive work).
  2. One-repetition maximum — Wikipedia. Supports: The use of 1RM as an upper bound for dosing a load as a percentage; the link to the 1RM calculator and the Epley formula.
  3. Weight plate — Wikipedia. Supports: Standard plate denominations in kilograms (1.25 / 2.5 / 5 kg and above) — the basis for choosing the rounding step.

Formula version:ww-pct-round-v1. Last reviewed: September 2, 2026