An HGV drivers' hours calculator helps UK drivers, transport managers and planners check a proposed shift before the vehicle moves. The important limits are not only the hours driven today. A compliant plan must also consider the 4.5-hour driving break, daily and weekly driving totals, daily rest, weekly rest and the separate road transport working-time rules.
This guide explains the main Great Britain assimilated drivers' hours limits for goods vehicles. It is a planning aid, not a tachograph analysis or legal determination. Different rules can apply to GB domestic operations, Northern Ireland, AETR journeys, exemptions and special transport situations.
What an HGV drivers' hours calculator should check
A useful calculator should show more than one remaining-hours figure. For a realistic plan, record:
- driving already completed today
- the longest driving period since the last qualifying break
- the daily driving allowance being used
- driving completed in the current fixed week
- the total for the previous and current fixed weeks
- the planned daily rest
- other work and periods of availability where relevant
The calculator can flag a plan that exceeds the entered limits, but the driver's tachograph and actual records remain the source of truth.
Daily HGV driving limits in the UK
Under the assimilated rules, the normal daily driving limit is 9 hours. It may be extended to 10 hours no more than twice during a fixed week.
A fixed week runs from 00:00 on Monday to 24:00 on Sunday. Extending a day to 10 hours does not increase the weekly or fortnightly limits.
Example:
- Monday: 10 hours
- Tuesday: 9 hours
- Wednesday: 10 hours
- Thursday: 9 hours
- Friday: 9 hours
- Saturday: 9 hours
This totals 56 hours. The two extended days are used, and the weekly maximum is reached. No further driving can be added in that fixed week under the standard limit.
The 4.5-hour driving rule and 45-minute break
After no more than 4 hours 30 minutes of accumulated driving, the driver must take a qualifying break of at least 45 minutes unless a rest period begins.
The 45-minute break may be split into:
- a break of at least 15 minutes
- followed later by a break of at least 30 minutes
The order matters. A 30-minute break followed by 15 minutes does not satisfy this split driving-break rule.
Other work does not reset accumulated driving time. Loading, paperwork, refuelling or helping in the warehouse may interrupt driving, but these activities are not a qualifying driving break.
Example: a driver completes 2 hours 30 minutes of driving, performs 45 minutes of other work and then drives another 2 hours. Accumulated driving is now 4 hours 30 minutes, so a qualifying break or rest is required before more driving.
Daily rest: 11 hours, reduced rest and split rest
A regular daily rest period is normally at least 11 hours.
A reduced daily rest is at least 9 hours but less than 11 hours. No more than three reduced daily rest periods may be taken between two weekly rest periods.
A regular daily rest may also be split into two periods:
- the first period must be at least 3 hours
- the second period must be at least 9 hours
The split must be completed in that order and within the applicable 24-hour period. A shift planner should therefore check the full time window, not only the total number of hours that appear to be free.
Weekly and fortnightly driving limits
The maximum driving time is:
- 56 hours in one fixed week
- 90 hours in any two consecutive fixed weeks
The fortnightly limit is easy to miss. If a driver completes 56 hours in week one, only 34 hours remain for week two because the combined total cannot exceed 90 hours.
The two-week check must roll forward. When a new fixed week starts, review the current week together with the immediately preceding week.
Weekly rest
A regular weekly rest period is at least 45 consecutive hours. A reduced weekly rest is at least 24 hours but less than 45 hours and normally requires compensation under the applicable rules.
Weekly-rest planning contains additional conditions, including when rest must start, where regular weekly rest may be taken and special provisions for some international goods journeys. Do not use a simple remaining-hours result as the only compliance check.
Driving-time breaks and working-time breaks are different
The Road Transport Working Time Regulations are separate from the drivers' hours rules.
For mobile workers, the main working-time limits include:
- an average of 48 working hours per week over the relevant reference period
- up to 60 working hours in a single week if the average limit is respected
- a total of at least 30 minutes of breaks when working between 6 and 9 hours
- a total of at least 45 minutes of breaks when working more than 9 hours
- individual working-time breaks of at least 15 minutes
Night-work limits and workforce agreements can also matter. A driving break may sometimes satisfy a working-time break at the same time, but driving time and working time must still be tracked separately.
Practical HGV shift-planning example
Assume a driver starts at 06:00 and the plan includes:
- 30 minutes of vehicle checks and paperwork
- 4 hours 30 minutes of driving
- 45 minutes of qualifying break
- 1 hour of unloading
- 4 hours 30 minutes of driving
Driving totals 9 hours, while the shift span and working time are longer because checks and unloading count as other work. The driving plan may fit the normal daily limit, but the planner must still check daily rest, weekly totals, the two-week total and working-time limits.
If another hour of driving is required, the day becomes a 10-hour extended driving day. The planner must confirm that one of the two weekly extensions is still available.
Common planning mistakes
- treating loading or paperwork as a driving break
- checking only today's driving and ignoring the 56-hour and 90-hour limits
- assuming that a 30-minute break followed by 15 minutes is a valid split
- forgetting how many 10-hour driving days have already been used
- counting time away from the vehicle as rest without checking the legal definition
- mixing drivers' hours with working-time limits
- using planned entries instead of actual tachograph records
- applying assimilated rules to a journey governed by different rules
How to use the EuroTruckTools planner
Enter the real shift start, driving already completed, other work, planned breaks and available rest. Review the result before accepting a route or assigning another collection.
Leave a safety margin for parking, traffic, loading delays and unexpected diversions. If the plan only works when every stop happens exactly on time, it is operationally fragile even when the arithmetic appears to fit.
Use EuroTruckTools to prepare and cross-check a plan. Before driving or assigning work, verify the result against the tachograph, company records, the rules that apply to the journey and the latest official GOV.UK guidance.
Official guidance and scope
The figures in this guide were checked against GOV.UK guidance for goods vehicles and current Great Britain road transport working-time guidance in August 2026.
This calculator does not assess every exemption, emergency situation, ferry or train interruption, multi-manning arrangement, GB domestic rule, Northern Ireland rule or AETR journey. Where the applicable regime is uncertain, confirm it with the operator's transport manager or a qualified compliance adviser.
Updated: 2026-09-09