Your Drone's Weight Is the Starting Point for Every Compliance Decision

Before you can understand where you can fly, how close you can get to people, or what registration you need, you need to know your drone's weight category. Under the UK's implementation of the Open Category framework, weight thresholds define the subcategory boundaries โ€” and the subcategory determines your operational envelope. MmowW's Drone Weight Category Calculator makes this determination instant. Here is how to use it.

Step 1: Open the Tool

Navigate to mmoww.net/uk/tools/weight-calculator/. No login, no download, no account needed. The tool is ready immediately.

Step 2: Enter the Maximum Take-Off Mass

Input your drone's MTOM in grams or kilograms. This is the total weight at the moment of takeoff, including:

  • Airframe and propellers
  • Battery or batteries
  • Camera, gimbal, and any mounted sensors
  • Any additional payload (spotlight, speaker, delivery parcel)
  • Propeller guards, if installed

If you are unsure of the exact MTOM, check the manufacturer's technical specifications. For custom builds or modified drones, weigh the complete assembly on a scale.

Step 3: Select the Class Marking

If your drone has a CE class marking, select it:

  • C0: Under 250g MTOM
  • C1: Under 900g MTOM
  • C2: Under 4kg MTOM
  • C3: Under 25kg MTOM
  • C4: Under 25kg MTOM (no automatic control modes)

If your drone does not have a class marking โ€” common for drones purchased before class marking requirements took effect โ€” select "No class marking" or "Legacy drone." The tool will apply the transitional provisions.

Step 4: Review Your Results

The calculator displays:

  • Open Category subcategory. Whether your drone falls under A1, A2, or A3. Each subcategory has different rules about proximity to people and operating environments.
  • Proximity rules. The minimum distance you must maintain from uninvolved persons during flight. This varies by subcategory and class marking.
  • Environmental restrictions. Whether you can fly over congested areas, near assemblies of people, or only in areas remote from people.
  • Weight threshold details. The specific boundaries that determine your category, so you understand how close you are to a threshold.
  • Transitional provisions. If you are using a legacy drone, the tool explains the transitional rules that currently apply and any future changes to be aware of.

Step 5: Test Alternative Configurations

If you use interchangeable payloads, run the calculator for each configuration. A drone that weighs 870g with a standard camera may weigh 1,200g with a thermal sensor. These two configurations fall into different weight categories with different operating rules. The tool saves no data between runs, so you can test as many configurations as needed.

Key Benefits

Instant answers. No need to cross-reference weight tables, class marking charts, and subcategory definitions. Enter your numbers and receive your category immediately. Threshold awareness. The tool shows you the exact boundaries, so you know if you are close to a category change. This is critical when adding accessories or changing batteries. Legacy drone support. Transitional rules for drones without class markings are a common source of confusion. The tool handles these cases explicitly. Free and private. No personal data is collected. No account is needed. Use the tool as often as you like without restriction.

Real Scenarios in Action

Scenario 1: Comparing two drones before purchase. An operator is choosing between two models โ€” one at 890g and one at 950g. The 60g difference crosses the 900g threshold. The calculator shows that the lighter drone qualifies for subcategory A1 (with a C1 marking), while the heavier one moves to A2 or A3 depending on its class marking. This information influences the purchase decision. Scenario 2: Assessing a custom build. A university research team has built a custom drone for environmental monitoring. The total assembly weighs 3.8kg. The calculator confirms this falls under subcategory A3 for Open Category operations (or A2 with a C2 marking and additional competency requirements). The team uses this to plan their flight operations within the correct regulatory framework. Scenario 3: Post-modification compliance check. After adding an upgraded camera system, an operator rechecks his drone's weight category. The heavier camera pushes the MTOM past a threshold, changing the applicable subcategory. The calculator flags this change, prompting the operator to adjust his operating practices.

FAQ

Q: Does the calculator account for different battery weights?

A: You should enter the MTOM using the heaviest battery you plan to fly with. If you use batteries of different weights, test the calculator with each to understand whether a heavier battery changes your category.

Q: What if my drone is exactly on a weight threshold?

A: Weight thresholds in the regulation are stated as "less than" specific values. A drone that weighs exactly 250g falls into the category above, not below. The calculator applies this rule correctly.

Q: Is MTOM the same as the weight on the box?

A: Not necessarily. The weight stated in marketing materials may be the airframe only, or with a specific battery. MTOM is the total weight at takeoff with all equipment installed. Check the manufacturer's technical specifications for the correct figure.

Try It Now โ€” Free, No Signup Required

Know your weight category before you fly. The MmowW Drone Weight Category Calculator gives you a regulation-backed answer in seconds.

Check your weight category now

What's Next?

With your weight category confirmed, verify your registration requirements using the Registration Requirement Checker and estimate your insurance needs with the Insurance Cost Estimator. MmowW's tools work as a system โ€” each one feeds into the next. All free, all designed for UK compliance. Loved for Safety. Ready for complete compliance management? Start your 14-day free trial โ€” ยฃ5.29/month, less than a coffee. Explore MmowW Drone SaaS