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When renting a crane, many people start with the question: "What tonnage crane should I use?" If you choose too small, it won't reach or won't be safe. If you choose too large, costs will be unnecessarily high. This article provides basic guidelines for choosing the right crane size to help you communicate confidently with service providers. Whether you're a business owner, construction contractor, or factory engineer in Chonburi, Rayong, or Chachoengsao, choosing the right crane size helps ensure on-time completion, safety, and budget savings.
What Does Crane "Tonnage" Mean?
Before choosing a crane size, you should understand that the "ton" rating — such as a 25-ton or 50-ton crane — refers to the Maximum Lifting Capacity at the closest boom radius. It does not mean a 25-ton crane can lift 25 tons at every distance. The farther the boom extends, the lower the lifting capacity becomes. Therefore, selecting the right size requires considering weight, lifting radius, and height together.
5 Key Factors for Choosing Crane Size
- Load Weight — The actual or estimated weight, e.g., containers (~2.5-4 tons), industrial machinery (~5-50 tons), steel structures, transformers (~3-20 tons). You must also include the weight of rigging equipment such as slings, chains, and spreader bars.
- Working Radius — The distance from the crane's center to the placement point. The farther the reach, the significantly lower the lifting capacity. For example, a 25-ton crane may only lift 5-8 tons at a 15-meter radius. This is critical for jobs where the crane parks far from the placement point, such as lifting over buildings or into factories.
- Lifting Height — If lifting to multi-story buildings or over obstacles, you need to account for main boom and jib length. Lifting to a 5-story building may require a boom length of 30-40 meters.
- Site Conditions — Is the ground strong enough to support the crane's weight? Is there enough space for outriggers? Is the access road wide enough for the crane? In tight spaces, you may need a smaller but higher-capacity crane, or use steel mats for ground support.
- Obstacles — High-voltage power lines, roof structures, trees, adjacent buildings, or chemical pipes in factories all affect crane size selection and lift planning. Jobs in industrial estates typically have more space constraints than general construction.
Understanding the Load Chart
Every crane has a Load Chart that shows the maximum weight it can lift at various working radii. For example, a 25-ton crane may have the following load ratings:
| Working Radius (m) | Max Lifting Capacity (tons) |
|---|---|
| 3 | 25.0 |
| 5 | 16.0 |
| 10 | 8.5 |
| 15 | 5.2 |
| 20 | 3.0 |
As you can see, a 25-ton crane at a 15-meter radius can only lift 5.2 tons. So if you need to lift 8 tons at 15 meters, you would need a larger crane such as a 50-ton. Actual figures vary by brand and model — always have an expert verify the Load Chart.
Crane Size Selection by Job Type
10-25 Ton Cranes: General Lifting
- Lifting air conditioning units to 2-3 story buildings
- Lifting water tanks, piles, construction materials
- Small structure demolition
- Lifting prefab houses, portable office containers
- Suitable for tight spaces, narrow alleys, easy access
25-80 Ton Cranes: Medium Industrial & Construction
- Steel structure installation for factory buildings
- Machinery lifting in industrial estates such as Amata City, Pinthong, Map Ta Phut
- Lifting transformers, chillers, compressors
- Building construction for 4-8 story buildings
- Container lifting at Laem Chabang Port
100-300 Ton Cranes: Heavy-Duty Jobs
- Heavy machinery lifting in petrochemical plants (Map Ta Phut, Rayong)
- Bridge construction, expressways, special structures
- Lifting reactors, vessels, columns in refineries
- Shutdown / turnaround work for large plants
- Jobs requiring extra-long reach or extreme lifting heights
Why Is a Safety Factor Necessary?
In practice, cranes must never lift more than 80% of the maximum rated capacity at any given working radius. For safety, if the Load Chart states 10 tons at 10 meters, the actual lift should not exceed 8 tons. The remaining margin accounts for factors such as wind, uneven ground, or load swing during lifting.
This is why reputable crane service providers often recommend a slightly larger crane than the actual load weight — not to charge more, but to ensure the safest and most efficient operation possible.
Common Mistakes in Choosing Crane Size
- Considering only weight, not radius — This is the most common mistake. A 5-ton load at 20 meters may require a 50-ton crane.
- Not accounting for rigging weight — Slings, chains, and spreader bars add 200-2,000 kg that must be included.
- Not surveying site access — Large cranes need wide roads. Cranes over 100 tons may require route permits.
- Choosing too small a crane to save money — If it can't lift, you'll need to swap cranes, wasting more time and money.
- Not checking the ground — Soft soil, filled land, or areas near canal edges can cause the crane to sink during lifting.
Summary: Prepare Your Information and Let Experts Calculate
If you're unsure what crane size you need, the easiest thing to do is prepare this information before contacting a service provider:
- Weight of the load (check specs or nameplate)
- Distance from crane parking to placement point (in meters)
- Required lifting height (building floor or meters)
- Take 3-5 photos of the job site with location pin
- Surrounding obstacles such as power lines, roofs, adjacent buildings
Then send it to the Crane Rental Eastern Region team for assessment. We'll recommend the most suitable and cost-effective crane size with safety as the top priority. We offer crane rental services for all sizes from 10-300 tons in Chonburi, Rayong, Chachoengsao, and throughout Eastern Thailand, with professional operators, full PJ.2 certification, and 24-hour service.